QUANTIFYING THE GLOBAL RATES OF NAUSEA AND VOMITING OF PREGNANCY: A META-ANALYSIS
Main Article Content
Keywords
Nausea, vomiting, pregnancy, epidemiology, prevalence, burden of disease, meta-analysis
Abstract
Background
Nausea and vomiting of pregnancy (NVP) is the most common medical condition in pregnancy, affecting women worldwide. It is unclear whether its prevalence and severity NVP are variable across different nations and races.
Purpose
To summarize global rates of NVP as reported in the literature using meta-analysis.
Methods
We searched Medline, Embase and Cochrane databases for all peer-reviewed articles reporting rates of NVP and/or hyperemesis gravidarum (HG). No restrictions were imposed on publication year or language. Numbers of women, studies and NVP rates were extracted and aggregated using a random effects model. Outcomes included: overall rates (i.e., women suffering any nausea or vomiting or both) in early and in late pregnancy, rates of nausea only, symptom severity, and HG rates.
Results
We identified 116 studies, rejecting 37 and accepting 79, of which 59 provided data for NVP (N=93,753 in 13 countries) and 26 for HG (N= 6,155,578). All developed regions of the world were represented (2 studies from Africa, 1 India; none from Latin America). Reported NVP rates varied from 35%-91% (median 69%); the meta-analytic average rate was 69.4% (CI95%:66.5%-72.3%). Among pregnant women, 32.7% had nausea without vomiting and 23.5% overall had NVP continuing into the third trimester. NVP was rated as mild in 40%, moderate in 46% and severe in 14% of cases. The prevalence of HG was 1.1% (CI95%:0.8%-1.3%), with a range of 0.3%-3.6%.
Conclusions
Almost 70% of women worldwide experience NVP, but reported rates vary widely. HG, the most severe form, affects 1.1%.
References
1. Weiss-Amer M. Medieval women's guides to food during pregnancy: origins, texts, and traditions. Can Bull Med History 1993;10:5-23.
2. Fairweather DV. Nausea and vomiting in pregnancy. Am J Obstet Gynecol 1968;102:135-75.
3. Peckham CH. Observations on 60 Cases of hyperemesis gravidarum. Am J Obstet Gynecol 1929;17:776-88.
4. Clark SM, Costantine MM, Hankins GD. Review of NVP and HG and early pharmacotherapeutic intervention. Obstet Gynecol Int 2012;252676. Epub 2011 Nov 24.
5. Munch S, Korst LM, Hernandez GD, Romero R, Goodwin TM. Health-related quality of life in women with nausea and vomiting of pregnancy: the importance of psychosocial context. J Perinatol 2011;31:10-20.
6. Chan OK, Sahota DS, Leung TY, Chan LW, Fung TY, Lau TK. Nausea and vomiting in health-related quality of life among Chinese pregnant women. Aust N Z J Obstet Gynaecol 2010;50:512-8.
7. Magee LA, Chandra K, Mazzotta P, Stewart D, Koren G, Guyatt GH. Development of a health-related quality of life instrument for nausea and vomiting of pregnancy. Am J Obstet Gynecol 2002; 186(5 Suppl Understanding):S232-8.
8. Lacasse A, Rey E, Ferreira E, Morin C, Bérard A. Determinants of early medical management of nausea and vomiting of pregnancy. Birth 2009;36:70-7.
9. Attard CL, Kohli MA, Coleman S, Bradley C, Hux M, Atanackovic G, Torrance GW. The burden of illness of severe nausea and vomiting of pregnancy in the United States. Am J Obstet Gynecol 2002;186(5 Suppl Understanding):S220-7.
10. Piwko C, Ungar WJ, Einarson TR, Wolpin J, Koren G. The weekly cost of nausea and vomiting of pregnancy for women calling the Toronto Motherisk Program. Curr Med Res Opin 2007;23:833-40.
11. American Congress of Obstetricians and Gynecologists. ACOG Practice Bulletin number 52: nausea and vomiting of pregnancy. Obstet Gynecol 2004;103(4):803-13.
12. Gadsby R, Barnie-Adshead AM, Jagger C. Pregnancy nausea related to women's obstetric and personal histories. Gynecol Obstet Invest 1997;43:108-11.
13. Arsenault M-Y, Lane CA. SOGC clinical practice guideline. The management of nausea and vomiting of pregnancy. J Obstet Gynaecol Can 2002; 24: 817-23. Available at: http://www.sogc.org/guidelines/public/120E-CPG-October2002.pdf
14. Goodwin TM. Hyperemesis gravidarum. Obstet Gynecol Clin North Am 2008;35:401-17.
15. Philip B. Hyperemesis gravidarum: literature review. Wis Med J 2003;102(3):46-51.
16. Macle L, Varlet MN, Cathébras P. Hyperemesis gravidarum: a rare but potentially severe complication of the first trimester of pregnancy. Rev Prat 2010;60:759-64.
17. Nageotte MP, Briggs GG, Towers CV, Asrat T. Droperidol and diphenhydramine in the management of hyperemesis gravidarum. Am J Obstet Gynecol 1996;174:1801-6.
18. Trogstad LI, Stoltenberg C, Magnus P, Skjaerven R, Irgens LM. Recurrence risk in hyperemesis gravidarum. BJOG 2005;112(12):1641-5.
19. Einarson TR. Pharmacoeconomic applications of meta-analysis for single groups: antifungal onychomycosis lacquers as example. Clin Ther 1997;19:559-69.
20. Chou FH, Chen CH, Kuo SH, Tzeng YL. Experience of Taiwanese women living with nausea and vomiting during pregnancy. J Midwifery Womens Health 2006;51:370-5.
21. Chou FH, Kuo SH, Wang RH. A longitudinal study of nausea and vomiting, fatigue and perceived stress in, and social support for, pregnant women through the three trimesters. Kaohsiung J Med Sci 2008;24:306-14.
22. Emelianova S, Mazzotta P, Einarson A, Koren G. Prevalence and severity of nausea and vomiting of pregnancy and effect of vitamin supplementation. Clin Invest Med 1999;22:106-10.
23. Fejzo MS, Ingles SA, Wilson M, et al. High prevalence of severe nausea and vomiting of pregnancy and hyperemesis gravidarum among relatives of affected individuals. Eur J Obstet Gynecol Reprod Biol 2008;141:13-7.
24. Kuo SH, Wang RH, Tseng HC, Jian SY, Chou FH. A comparison of different severities of nausea and vomiting during pregnancy relative to stress, social support, and maternal adaptation. J Midwifery Womens Health 2007;52(1):e1-7.
25. Locock L, Alexander J, Rozmovits L. Women's responses to nausea and vomiting in pregnancy. Midwifery 2008;24:143-52.
26. Mazzotta P, Stewart D, Atanackovic G, Koren G, Magee LA. Psychosocial morbidity among women with nausea and vomiting of pregnancy: prevalence and association with anti-emetic therapy. J Psychosom Obstet Gynaecol 2000;21:129-36.
27. Corey LA, Berg K, Solaas MH, Nance WE. The epidemiology of pregnancy complications and outcome in a Norwegian twin population. Obstet Gynecol 1992;80:989-94.
28. Dickens G, Trethowan WH. Cravings and aversions during pregnancy. J Psychosom Res 1971;15:259-68.
29. Markl GE, Strunz-Lehner C, Egen-Lappe V, Lack N, Hasford J. The association of psychosocial factors with nausea and vomiting during pregnancy. J Psychosom Obstet Gynaecol 2008;29:17-22.
30. Markl GE, Strunz-Lehner C, Egen-Lappe V, Hasford J. Prescribing patterns of anti-emetic drugs during pregnancy in Germany. Arch Gynecol Obstet 2007;275:461-7.
31. Pepper GV, Craig Roberts S. Rates of nausea and vomiting in pregnancy and dietary characteristics across populations. Proc Biol Sci 2006;273(1601):2675-9.
32. Smith C, Crowther C, Beilby J, Dandeaux J. The impact of nausea and vomiting on women: a burden of early pregnancy. Aust N Z J Obstet Gynaecol 2000;40:397-401.
33. Tylden E. Hyperemesis and physiological vomiting. J Psychosom Res 1968;12:86-93.
34. Zhang J, Cai WW. Severe vomiting during pregnancy: antenatal correlates and fetal outcomes. Epidemiology 1991;2:454-7.
35. Chan RL, Olshan AF, Savitz DA, et al. Severity and duration of nausea and vomiting symptoms in pregnancy and spontaneous abortion. Hum Reprod 2010;25:2907-12.
36. Klebanoff MA, Mills JL. Is vomiting during pregnancy teratogenic? Br Med J (Clin Res Ed) 1986;292(6522):724-6.
37. Weigel MM, Weigel RM. The association of reproductive history, demographic factors, and alcohol and tobacco consumption with the risk of developing nausea and vomiting in early pregnancy. Am J Epidemiol 1988;127:562-70.
38. Flaxman SM, Sherman PW. Morning sickness: a mecjanism for protecting mother and embryo. Q Rev Biol 2000;75:113-48.
39. Bashiri A, Neumann L, Maymon E, Katz M. Hyperemesis gravidarum: epidemiologic features, complications and outcome. Eur J Obstet Gynecol Reprod Biol 1995;63:135-8.
40. Borgeat A, Fathi M, Valiton A. Hyperemesis gravidarum: is serotonin implicated? Am J Obstet Gynecol 1997;176:476-7.
41. Depue RH, Bernstein L, Ross RK, Judd HL, Henderson BE. Hyperemesis gravidarum in relation to estradiol levels, pregnancy outcome, and other maternal factors: a seroepidemiologic study. Am J Obstet Gynecol 1987;156:1137-41.
42. Godsey RK, Newman RB. Hyperemesis gravidarum. A comparison of single and multiple admissions. J Reprod Med 1991;36:287-90.
43. Naef RW, Chauhan SP, Roach H, Roberts WE, Travis KH, Morrison JC. Treatment for hyperemesis gravidarum in the home: an alternative to hospitalization. J Perinatol 1995;15:289-92.
44. Jørgensen KT, Nielsen NM, Pedersen BV, Jacobsen S, Frisch M. Hyperemesis, gestational hypertensive disorders, pregnancy losses and risk of autoimmune diseases in a Danish population-based cohort. J Autoimmun 2012;38(2-3):J120-8.
45. Kuru O, Sen S, Akbay?r O, Goksedef BP, Ozsürmeli M, Attar E, Sayg?l? H. Outcomes of pregnancies complicated by hyperemesis gravidarum. Arch Gynecol Obstet 2012;285:1517-21.
46. Safari HR, Alsulyman OM, Gherman RB, Goodwin TM. Experience with oral methylprednisolone in the treatment of refractory hyperemesis gravidarum. Am J Obstet Gynecol 1998;178:1054-8.
47. Saha S, Manlolo J, McGowan CE, Reinert S, Degli Esposti S. Gastroenterology consultations in pregnancy. J Womens Health (Larchmt) 2011;20:359-63.
48. Tan PC, Vani S, Lim BK, Omar SZ. Anxiety and depression in hyperemesis gravidarum: prevalence, risk factors and correlation with clinical severity. Eur J Obstet Gynecol Reprod Biol 2010; 149: 153-8.
49. Uguz F, Gezginc K, Kayhan F, Cicek E, Kantarci AH. Is hyperemesis gravidarum associated with mood, anxiety and personality disorders: a case-control study. Gen Hosp Psychiatry 2012; 34: 398-402.
50. van Stuijvenberg ME, Schabort I, Labadarios D, Nel JT. The nutritional status and treatment of patients with hyperemesis gravidarum. Am J Obstet Gynecol 1995;172:1585-91.
51. Franks AL, Kendrick JS, Olson DR, Atrash HK, Saftlas AF, Moien M. Hospitalization for pregnancy complications, United States, 1986 and 1987. Am J Obstet Gynecol 1992;166:1339-44.
52. Vilming B, Nesheim BI. Hyperemesis gravidarum in a contemporary population in Oslo. Acta Obstet Gynecol Scand 2000;79:640-3.
53. Abraham S, King W, Llewellyn-Jones D. Attitudes to body weight, weight gain and eating behavior in pregnancy. J Psychosom Obstet Gynaecol 1994;15:189-95.
54. Ananth CV, Rao PS. Epidemiology of nausea and vomiting of pregnancy and its relation to fetal outcome in a rural area. J Trop Pediatr 1993;39:313.
55. Biggs JS. Vomiting in pregnancy: Causes and management. Drugs 1975;9:299-306.
56. Boneva RS, Moore CA, Botto L, Wong LY, Erickson JD. Nausea during pregnancy and congenital heart defects: a population-based case control study. Am J Epidemiol 1999;149:717-25.
57. Brandes JM. First-trimester nausea and vomiting as related to outcome of pregnancy. Obstet Gynecol 1967;30:427-31.
58. Brown JE, Kahn ES, Hartman TJ. Profet, profits, and proof: do nausea and vomiting of early pregnancy protect women from "harmful" vegetables? Am J Obstet Gynecol 1997;176(1 Pt 1):179-81.
59. Chan RL, Olshan AF, Savitz DA, et al. Maternal influences on nausea and vomiting in early pregnancy. Matern Child Health J 2011;15:122-7.
60. Chin RK. Antenatal complications and perinatal outcome in patients with nausea and vomiting-complicated pregnancy. Eur J Obstet Gynecol Reprod Biol 1989;33:215-9.
61. Chou FH, Lin LL, Cooney AT, Walker LO, Riggs MW. Psychosocial factors related to nausea, vomiting, and fatigue in early pregnancy. J Nurs Scholarsh 2003;35:119-25.
62. Chou FH, Avant KC, Kuo SH, Fetzer SJ. Relationships between nausea and vomiting, perceived stress, social support, pregnancy planning, and psychosocial adaptation in a sample of mothers: a questionnaire survey. Int J Nurs Stud 2008;45:1185-91.
63. Crystal SR, Bowen DJ, Bernstein IL. Morning sickness and salt intake, food cravings and food aversion. Physio Behav 1999;67:181-7.
64. Davies TW, Williams DR, Whitaker RH. Risk factors for undescended testis. Int J Epidemiol 1986;15:197-201.
65. Diggory Pl, Tomkinson JS. Nausea and vomiting in pregnancy. A trial of meclozine dihydrochloride with and without pyridoxine. Lancet 1962;2(7252):370-2.
66. DiIorio C. First trimester nausea in pregnant teenagers: incidence, characteristics, intervention. Nurs Res 1985;34:372-4.
67. Drake ML, Verhulst D, Fawcett J. Physical and psychological symptoms experienced by Canadian women and their husbands during pregnancy and the postpartum. J Adv Nurs 1988;13:436-40.
68. Evans AJ, Li TC, Selby C, Jeffcoate WJ. Morning sickness and thyroid function. Br J Obstet Gynaecol 1986;93:520-2.
69. Fairburn CG, Welch SL. The impact of pregnancy on eating habits and attitudes to shape and weight. Int J Eating Disord 1990;9:153-60.
70. Fairburn CG, Stein A, Jones R. Eating habits and eating disorders during pregnancy. Psychosom Med 1992;54:665-72.
71. Fawcett J, York R. Spouses' physical and psychological symptoms during pregnancy and the postpartum. Nurs Res 1986;35:144-8.
72. Fenster L, Eskenazi B, Windham GC, Swan SH. Caffeine consumption during pregnancy and spontaneous abortion. Epidemiology 1991;2:168-74.
73. Fitzgerald CM. Nausea and vomiting in pregnancy. Br J Med Psychol 1984;57:159-65.
74. Gadsby R, Barnie-Adshead AM, Jagger C. A prospective study of nausea and vomiting during pregnancy. Br J Gen Pract 1993;43:245-8.
75. Jahangiri F, Hirshfeld-Cytron J, Goldman K, Pavone ME, Gerber S, Klock SC. Correlation between depression, anxiety, and nausea and vomiting during pregnancy in an in vitro fertilization population: a pilot study. J Psychosom Obstet Gynaecol 2011;32:113-8.
76. Järnfelt-Samsioe A, Samsioe G, Velinder GM. Nausea and vomiting in pregnancy--a contribution to its epidemiology. Gynecol Obstet Invest 1983;16:221-9.
77. Järnfelt-Samsioe A, Eriksson B, Waldenström J, Samsioe G. Some new aspects on emesis gravidarum. Relations to clinical data, serum electrolytes, total protein and creatinine. Gynecol Obstet Invest 1985;19:174-86.
78. Jinadu MK, Daramola SM. Emotional changes in pregnancy and early puerperium among the Yoruba women of Nigeria. Int J Soc Psychiatry 1990;36:93-8.
79. Källén B, Lundberge G, Aberge A. Relationship between vitamin use, smoking and nausea and vomiting of pregnancy. Acta Obstet Gynecol Scand 2003;82:916-20.
80. Klebanoff MA, Koslowe PA, Kaslow R, Rhoads GG. Epidemiology of vomiting in early pregnancy. Obstet Gynecol 1985;66:612-6.
81. Kramer J. Nausea 1957;9:586-94.
82. Speert H, Guttmacher AF. Frequency and significance of bleeding in early pregnancy. J Am Med Assoc 1954;155:712-5.
83. Stewart J, Wheeler E, Scofield C. Regional differences in British attitudes to diet in pregnancy: priorities and pragmatism. Ecol Food Nutr 1988;20:211-29.
84. Tierson FD, Olsen CL, Hook EB. Nausea and vomiting of pregnancy and association with pregnancy outcome. Am J Obstet Gynecol 1986;155:1017-22.
85. Uddenberg N, Nilsson Å, Almgren PE. Nausea in pregnancy: psychological and psychosomatic aspects. J Psychosomat Res 1971;15:269-76.
86. Vellacott ID, Cooke EJ, James CE. Nausea and vomiting in early pregnancy. Int J Gynaecol Obstet 1988;27:57-62.
87. Walker AR, Walker BF, Jones J, Verardi M, Walker C. Nausea and vomiting and dietary cravings and aversions during pregnancy in South African women. Br J Obstet Gynaecol 1985;92:484-9.
88. Weigel MM, Weigel RM. Nausea and vomiting of early pregnancy and pregnancy outcome. An epidemiological study. BJOG: Int J Obstet Gynaecol 1989;96:1304-11.
89. Werler MM, Pober BR, Nelson K, Holmes LB. Reporting accuracy among mothers of malformed and nonmalformed infants. Am J Epidemiol 1989;129:415-21. and vomiting in pregnancy: prevalence and relationship with psychosocial determinants of health. Master of Nursing thesis, College of Nursing, University of Saskatchewan, Saskatoon, SK, 2010.
90. Kricker A, Elliott J, Forrest J, McCredie J. Congenital limb deficiency: maternal factors in pregnancy. Aust N Z J Obstet Gynaecol 1986;26:272-5.
91. Kullander S, Källén B. A prospective study of drugs and pregnancy. II. Anti-emetic drugs. Acta Obstet Gynecol Scand 1976;55:105-11.
92. Lacroix R, Eason E, Melzack R. Nausea and vomiting during pregnancy: A prospective study of its frequency, intensity, and patterns of change. Am J Obstet Gynecol 2000;182:931-7.
93. Lindseth G, Vari P. Nausea and vomiting in late pregnancy. Health Care Women Int 2005;26:372-86.
94. Little RE, Hook EB. Maternal alcohol and tobacco consumption and their association with nausea and vomiting during pregnancy. Acta Obstet Gynecol Scand 1979;58:15-7.
95. Louik C, Hernandez-Diaz S, Werler MM, Mitchell AA. Nausea and vomiting in pregnancy: maternal characteristics and risk factors. Paediatr Perinat Epidemiol 2006;20:270-8.
96. Masson GM, Anthony F, Chau E. Serum chorionic gonadotrophin (hCG), schwangerschaftsprotein 1 (SP1), progesterone and oestradiol levels in patients with nausea and vomiting in early pregnancy. Br J Obstet Gynaecol 1985;92:211-5.
97. McBride ML, Van den Steen N, Lamb CW, Gallagher RP. Maternal and gestational factors in cryptorchidism. Int J Epidemiol 1991;20:964-70.
98. Medalie JH. Relationship between nausea and/or vomiting in early pregnancy and abortion. Lancet 1957;273(6986):117-9.
99. Meyer LC, Peacock JL, Bland JM, Anderson HR. Symptoms and health problems in pregnancy: their association with social factors, smoking, alcohol, caffeine and attitude to pregnancy. Paediatr Perinat Epidemiol 1994;8:145-55.
100. Milkovich L, van den Berg BJ. An evaluation of the teratogenicity of certain antinauseant drugs. Am J Obstet Gynecol 1976;125:244-8.
101. Mori M, Amino N, Tamaki H, Miyai K, Tanizawa O. Morning sickness and thyroid function in normal pregnancy. Obstet Gynecol 1988;72(3 Pt 1):355-9.
102. O'Brien B, Zhou Q. Variables related to nausea and vomiting during pregnancy. Birth 1995;22:93-100.
103. Paarlberg KM, Vingerhoets AJ, Passchier J, Heinen AG, Dekker GA, van Geijn HP. Psychosocial factors as predictors of maternal well-being and pregnancy-related complaints. J Psychosom Obstet Gynaecol 1996;17:93-102.
104. Petitti DB. Nausea and pregnancy outcome. Birth 1986;13:223-6.
105. Robertson GG. Nausea and vomiting of pregnancy; a study in psychosomatic and social medicine. Lancet 1946;2(6419):336-41.
106. Semmens JP. Hyperemesis gravidarum evaluation and treatment. Obstet Gynecol
107. Whitehead SA, Andrews PLR, Chamberlain GVP. Characterisation of nausea and vomiting in early pregnancy: a survey of 1000 women. J Obstet Gynaecol 1992;12:364-9.
108. Wolkind S, Zajicek E. Psycho-social correlates of nausea and vomiting in pregnancy. J Psychosom Res 1978;22:1-5.
109. Yerushalmy J, Milkovich L. Evaluation of the teratogenic effect of meclizine in man. Am J Obstet Gynecol 1965;93:553-62.
110. Adams MM, Harlass FE, Sarno AP, Read JA, Rawlings JS. Antenatal hospitalization among enlisted servicewomen, 1987-1990. Obstet Gynecol 1994;84:35-9.
111. Askling J, Erlandsson G, Kaijser M, Akre O, Ekbom A. Sickness in pregnancy and sex of child. Lancet 1999;354(9195):2053.
112. Bacak SJ, Callaghan WM, Dietz PM, Crouse C. Pregnancy-associated hospitalizations in the United States, 1999-2000. Am J Obstet Gynecol 2005;192(2):592-7.
113. Bailit JL. Hyperemesis gravidarium: Epidemiologic findings from a large cohort. Am J Obstet Gynecol 2005;193(3 Pt 1):811-4.
114. Bennett TA, Kotelchuck M, Cox CE, Tucker MJ, Nadeau DA. Pregnancy-associated hospitalizations in the United States in 1991 and 1992: a comprehensive view of maternal morbidity. Am J Obstet Gynecol 1998;178:346-54.
115. Cedergren M, Brynhildsen J, Josefsson A, Sydsjö A, Sydsjö G. Hyperemesis gravidarum that requires hospitalization and the use of antiemetic drugs in relation to maternal body composition. Am J Obstet Gynecol 2008; 198(4):412.e1-5.
116. Fell DB, Dodds L, Joseph KS, Allen VM, Butler B. Risk factors for hyperemesis gravidarum requiring hospital admission during pregnancy. Obstet Gynecol 2006 Feb;107(2 Pt 1):277-84.
117. Fischer-Rasmussen W, Kjaer SK, Dahl C, Asping U. Ginger treatment of hyperemesis gravidarum. Eur J Obstet Gynecol Reprod Biol 1990;38:19-24.
118. Fitzgerald JPB. Epidemiology of hyperemesis gravidarum. Lancet 1956: I (May 12):660-2.
119. Gazmararian JA, Petersen R, Jamieson DJ, Schild L, Adams MM, Deshpande AD, Franks AL. Hospitalizations during pregnancy among managed care enrollees. Obstet Gynecol 2002; 100: 94-100.
120. Hallak M, Tsalamandris K, Dombrowski MP, Isada NB, Pryde PG, Evans MI. Hyperemesis gravidarum. Effects on fetal outcome. J Reprod Med 1996;41:871-4.
121. Jimenez V, Marleau JD. Is hyperemesis gravidarum related to country of origin? Short report. Can Fam Physician 2000;46:1607-8.
122. Källén B. Hyperemesis during pregnancy and delivery outcome: a registry study. Eur J Obstet Gynecol Reprod Biol 1987;26:291-302.
123. Matsuo K, Ushioda N, Nagamatsu M, Kimura T. Hyperemesis gravidarum in Eastern Asian population. Gynecol Obstet Invest 2007;64:213-6.
124. Reid DE, Teel HM. The treatment of the vomiting of early pregnancy. N Eng J Med 1938;218:109-13.
125. Scott CL, Chavez GF, Atrash HK, Taylor DJ, Shah RS, Rowley D. Hospitalizations for severe complications of pregnancy, 1987-1992. Obstet Gynecol 1997;90:225-9.
126. Tsang IS, Katz VL, Wells SD. Maternal and fetal outcomes in hyperemesis gravidarum. Internat. J Gynecol Obstet 1996;55:231-5.
127. Vikanes A, Grjibovski AM, Vangen S, Magnus P. Variations in prevalence of hyperemesis gravidarum by country of birth: A study of 900,074 pregnancies in Norway 1967-2005. Scand J Public Health 2008;36:135-42.
128. Gadsby R, Barnie-Adshead AM. Nausea and vomiting of pregnancy: clinical information about nausea and vomiting of pregnancy and its relation to various aspects of womens’ personal and obstetric histories and other significant factors related to nausea and vomiting of pregnancy or hyperemesis gravidarum. A literature review. Available at: http://www.pregnancysicknesssupport.org.uk/documents/NVP-lit-review.pdf
129. Koren G, Maltepe C. Pre-emptive therapy for severe nausea and vomiting of pregnancy and hyperemesis gravidarum. J Obstet Gynaecol 2004;24:530-3.
130. Koren G, Maltepe C. Preventing recurrence of severe morning sickness. Can Fam Physician 2006;52:1545-6.
131. Czeizel AE, Dudas I, Fritz G, Técsöi A, Hanck A, Kunovits G. The effect of periconceptional multivitamin-mineral supplementation on vertigo, nausea and vomiting in the first trimester of pregnancy. Arch Gynecol Obstet 1992;251:181-5.
132. Koren G, Clark S, Hankins GD, et al. Effectiveness of delayed-release doxylamine and pyridoxine for nausea and vomiting of pregnancy: a randomized placebo controlled trial. Am J Obstet Gynecol 2010;203(6):571.e1-7.
2. Fairweather DV. Nausea and vomiting in pregnancy. Am J Obstet Gynecol 1968;102:135-75.
3. Peckham CH. Observations on 60 Cases of hyperemesis gravidarum. Am J Obstet Gynecol 1929;17:776-88.
4. Clark SM, Costantine MM, Hankins GD. Review of NVP and HG and early pharmacotherapeutic intervention. Obstet Gynecol Int 2012;252676. Epub 2011 Nov 24.
5. Munch S, Korst LM, Hernandez GD, Romero R, Goodwin TM. Health-related quality of life in women with nausea and vomiting of pregnancy: the importance of psychosocial context. J Perinatol 2011;31:10-20.
6. Chan OK, Sahota DS, Leung TY, Chan LW, Fung TY, Lau TK. Nausea and vomiting in health-related quality of life among Chinese pregnant women. Aust N Z J Obstet Gynaecol 2010;50:512-8.
7. Magee LA, Chandra K, Mazzotta P, Stewart D, Koren G, Guyatt GH. Development of a health-related quality of life instrument for nausea and vomiting of pregnancy. Am J Obstet Gynecol 2002; 186(5 Suppl Understanding):S232-8.
8. Lacasse A, Rey E, Ferreira E, Morin C, Bérard A. Determinants of early medical management of nausea and vomiting of pregnancy. Birth 2009;36:70-7.
9. Attard CL, Kohli MA, Coleman S, Bradley C, Hux M, Atanackovic G, Torrance GW. The burden of illness of severe nausea and vomiting of pregnancy in the United States. Am J Obstet Gynecol 2002;186(5 Suppl Understanding):S220-7.
10. Piwko C, Ungar WJ, Einarson TR, Wolpin J, Koren G. The weekly cost of nausea and vomiting of pregnancy for women calling the Toronto Motherisk Program. Curr Med Res Opin 2007;23:833-40.
11. American Congress of Obstetricians and Gynecologists. ACOG Practice Bulletin number 52: nausea and vomiting of pregnancy. Obstet Gynecol 2004;103(4):803-13.
12. Gadsby R, Barnie-Adshead AM, Jagger C. Pregnancy nausea related to women's obstetric and personal histories. Gynecol Obstet Invest 1997;43:108-11.
13. Arsenault M-Y, Lane CA. SOGC clinical practice guideline. The management of nausea and vomiting of pregnancy. J Obstet Gynaecol Can 2002; 24: 817-23. Available at: http://www.sogc.org/guidelines/public/120E-CPG-October2002.pdf
14. Goodwin TM. Hyperemesis gravidarum. Obstet Gynecol Clin North Am 2008;35:401-17.
15. Philip B. Hyperemesis gravidarum: literature review. Wis Med J 2003;102(3):46-51.
16. Macle L, Varlet MN, Cathébras P. Hyperemesis gravidarum: a rare but potentially severe complication of the first trimester of pregnancy. Rev Prat 2010;60:759-64.
17. Nageotte MP, Briggs GG, Towers CV, Asrat T. Droperidol and diphenhydramine in the management of hyperemesis gravidarum. Am J Obstet Gynecol 1996;174:1801-6.
18. Trogstad LI, Stoltenberg C, Magnus P, Skjaerven R, Irgens LM. Recurrence risk in hyperemesis gravidarum. BJOG 2005;112(12):1641-5.
19. Einarson TR. Pharmacoeconomic applications of meta-analysis for single groups: antifungal onychomycosis lacquers as example. Clin Ther 1997;19:559-69.
20. Chou FH, Chen CH, Kuo SH, Tzeng YL. Experience of Taiwanese women living with nausea and vomiting during pregnancy. J Midwifery Womens Health 2006;51:370-5.
21. Chou FH, Kuo SH, Wang RH. A longitudinal study of nausea and vomiting, fatigue and perceived stress in, and social support for, pregnant women through the three trimesters. Kaohsiung J Med Sci 2008;24:306-14.
22. Emelianova S, Mazzotta P, Einarson A, Koren G. Prevalence and severity of nausea and vomiting of pregnancy and effect of vitamin supplementation. Clin Invest Med 1999;22:106-10.
23. Fejzo MS, Ingles SA, Wilson M, et al. High prevalence of severe nausea and vomiting of pregnancy and hyperemesis gravidarum among relatives of affected individuals. Eur J Obstet Gynecol Reprod Biol 2008;141:13-7.
24. Kuo SH, Wang RH, Tseng HC, Jian SY, Chou FH. A comparison of different severities of nausea and vomiting during pregnancy relative to stress, social support, and maternal adaptation. J Midwifery Womens Health 2007;52(1):e1-7.
25. Locock L, Alexander J, Rozmovits L. Women's responses to nausea and vomiting in pregnancy. Midwifery 2008;24:143-52.
26. Mazzotta P, Stewart D, Atanackovic G, Koren G, Magee LA. Psychosocial morbidity among women with nausea and vomiting of pregnancy: prevalence and association with anti-emetic therapy. J Psychosom Obstet Gynaecol 2000;21:129-36.
27. Corey LA, Berg K, Solaas MH, Nance WE. The epidemiology of pregnancy complications and outcome in a Norwegian twin population. Obstet Gynecol 1992;80:989-94.
28. Dickens G, Trethowan WH. Cravings and aversions during pregnancy. J Psychosom Res 1971;15:259-68.
29. Markl GE, Strunz-Lehner C, Egen-Lappe V, Lack N, Hasford J. The association of psychosocial factors with nausea and vomiting during pregnancy. J Psychosom Obstet Gynaecol 2008;29:17-22.
30. Markl GE, Strunz-Lehner C, Egen-Lappe V, Hasford J. Prescribing patterns of anti-emetic drugs during pregnancy in Germany. Arch Gynecol Obstet 2007;275:461-7.
31. Pepper GV, Craig Roberts S. Rates of nausea and vomiting in pregnancy and dietary characteristics across populations. Proc Biol Sci 2006;273(1601):2675-9.
32. Smith C, Crowther C, Beilby J, Dandeaux J. The impact of nausea and vomiting on women: a burden of early pregnancy. Aust N Z J Obstet Gynaecol 2000;40:397-401.
33. Tylden E. Hyperemesis and physiological vomiting. J Psychosom Res 1968;12:86-93.
34. Zhang J, Cai WW. Severe vomiting during pregnancy: antenatal correlates and fetal outcomes. Epidemiology 1991;2:454-7.
35. Chan RL, Olshan AF, Savitz DA, et al. Severity and duration of nausea and vomiting symptoms in pregnancy and spontaneous abortion. Hum Reprod 2010;25:2907-12.
36. Klebanoff MA, Mills JL. Is vomiting during pregnancy teratogenic? Br Med J (Clin Res Ed) 1986;292(6522):724-6.
37. Weigel MM, Weigel RM. The association of reproductive history, demographic factors, and alcohol and tobacco consumption with the risk of developing nausea and vomiting in early pregnancy. Am J Epidemiol 1988;127:562-70.
38. Flaxman SM, Sherman PW. Morning sickness: a mecjanism for protecting mother and embryo. Q Rev Biol 2000;75:113-48.
39. Bashiri A, Neumann L, Maymon E, Katz M. Hyperemesis gravidarum: epidemiologic features, complications and outcome. Eur J Obstet Gynecol Reprod Biol 1995;63:135-8.
40. Borgeat A, Fathi M, Valiton A. Hyperemesis gravidarum: is serotonin implicated? Am J Obstet Gynecol 1997;176:476-7.
41. Depue RH, Bernstein L, Ross RK, Judd HL, Henderson BE. Hyperemesis gravidarum in relation to estradiol levels, pregnancy outcome, and other maternal factors: a seroepidemiologic study. Am J Obstet Gynecol 1987;156:1137-41.
42. Godsey RK, Newman RB. Hyperemesis gravidarum. A comparison of single and multiple admissions. J Reprod Med 1991;36:287-90.
43. Naef RW, Chauhan SP, Roach H, Roberts WE, Travis KH, Morrison JC. Treatment for hyperemesis gravidarum in the home: an alternative to hospitalization. J Perinatol 1995;15:289-92.
44. Jørgensen KT, Nielsen NM, Pedersen BV, Jacobsen S, Frisch M. Hyperemesis, gestational hypertensive disorders, pregnancy losses and risk of autoimmune diseases in a Danish population-based cohort. J Autoimmun 2012;38(2-3):J120-8.
45. Kuru O, Sen S, Akbay?r O, Goksedef BP, Ozsürmeli M, Attar E, Sayg?l? H. Outcomes of pregnancies complicated by hyperemesis gravidarum. Arch Gynecol Obstet 2012;285:1517-21.
46. Safari HR, Alsulyman OM, Gherman RB, Goodwin TM. Experience with oral methylprednisolone in the treatment of refractory hyperemesis gravidarum. Am J Obstet Gynecol 1998;178:1054-8.
47. Saha S, Manlolo J, McGowan CE, Reinert S, Degli Esposti S. Gastroenterology consultations in pregnancy. J Womens Health (Larchmt) 2011;20:359-63.
48. Tan PC, Vani S, Lim BK, Omar SZ. Anxiety and depression in hyperemesis gravidarum: prevalence, risk factors and correlation with clinical severity. Eur J Obstet Gynecol Reprod Biol 2010; 149: 153-8.
49. Uguz F, Gezginc K, Kayhan F, Cicek E, Kantarci AH. Is hyperemesis gravidarum associated with mood, anxiety and personality disorders: a case-control study. Gen Hosp Psychiatry 2012; 34: 398-402.
50. van Stuijvenberg ME, Schabort I, Labadarios D, Nel JT. The nutritional status and treatment of patients with hyperemesis gravidarum. Am J Obstet Gynecol 1995;172:1585-91.
51. Franks AL, Kendrick JS, Olson DR, Atrash HK, Saftlas AF, Moien M. Hospitalization for pregnancy complications, United States, 1986 and 1987. Am J Obstet Gynecol 1992;166:1339-44.
52. Vilming B, Nesheim BI. Hyperemesis gravidarum in a contemporary population in Oslo. Acta Obstet Gynecol Scand 2000;79:640-3.
53. Abraham S, King W, Llewellyn-Jones D. Attitudes to body weight, weight gain and eating behavior in pregnancy. J Psychosom Obstet Gynaecol 1994;15:189-95.
54. Ananth CV, Rao PS. Epidemiology of nausea and vomiting of pregnancy and its relation to fetal outcome in a rural area. J Trop Pediatr 1993;39:313.
55. Biggs JS. Vomiting in pregnancy: Causes and management. Drugs 1975;9:299-306.
56. Boneva RS, Moore CA, Botto L, Wong LY, Erickson JD. Nausea during pregnancy and congenital heart defects: a population-based case control study. Am J Epidemiol 1999;149:717-25.
57. Brandes JM. First-trimester nausea and vomiting as related to outcome of pregnancy. Obstet Gynecol 1967;30:427-31.
58. Brown JE, Kahn ES, Hartman TJ. Profet, profits, and proof: do nausea and vomiting of early pregnancy protect women from "harmful" vegetables? Am J Obstet Gynecol 1997;176(1 Pt 1):179-81.
59. Chan RL, Olshan AF, Savitz DA, et al. Maternal influences on nausea and vomiting in early pregnancy. Matern Child Health J 2011;15:122-7.
60. Chin RK. Antenatal complications and perinatal outcome in patients with nausea and vomiting-complicated pregnancy. Eur J Obstet Gynecol Reprod Biol 1989;33:215-9.
61. Chou FH, Lin LL, Cooney AT, Walker LO, Riggs MW. Psychosocial factors related to nausea, vomiting, and fatigue in early pregnancy. J Nurs Scholarsh 2003;35:119-25.
62. Chou FH, Avant KC, Kuo SH, Fetzer SJ. Relationships between nausea and vomiting, perceived stress, social support, pregnancy planning, and psychosocial adaptation in a sample of mothers: a questionnaire survey. Int J Nurs Stud 2008;45:1185-91.
63. Crystal SR, Bowen DJ, Bernstein IL. Morning sickness and salt intake, food cravings and food aversion. Physio Behav 1999;67:181-7.
64. Davies TW, Williams DR, Whitaker RH. Risk factors for undescended testis. Int J Epidemiol 1986;15:197-201.
65. Diggory Pl, Tomkinson JS. Nausea and vomiting in pregnancy. A trial of meclozine dihydrochloride with and without pyridoxine. Lancet 1962;2(7252):370-2.
66. DiIorio C. First trimester nausea in pregnant teenagers: incidence, characteristics, intervention. Nurs Res 1985;34:372-4.
67. Drake ML, Verhulst D, Fawcett J. Physical and psychological symptoms experienced by Canadian women and their husbands during pregnancy and the postpartum. J Adv Nurs 1988;13:436-40.
68. Evans AJ, Li TC, Selby C, Jeffcoate WJ. Morning sickness and thyroid function. Br J Obstet Gynaecol 1986;93:520-2.
69. Fairburn CG, Welch SL. The impact of pregnancy on eating habits and attitudes to shape and weight. Int J Eating Disord 1990;9:153-60.
70. Fairburn CG, Stein A, Jones R. Eating habits and eating disorders during pregnancy. Psychosom Med 1992;54:665-72.
71. Fawcett J, York R. Spouses' physical and psychological symptoms during pregnancy and the postpartum. Nurs Res 1986;35:144-8.
72. Fenster L, Eskenazi B, Windham GC, Swan SH. Caffeine consumption during pregnancy and spontaneous abortion. Epidemiology 1991;2:168-74.
73. Fitzgerald CM. Nausea and vomiting in pregnancy. Br J Med Psychol 1984;57:159-65.
74. Gadsby R, Barnie-Adshead AM, Jagger C. A prospective study of nausea and vomiting during pregnancy. Br J Gen Pract 1993;43:245-8.
75. Jahangiri F, Hirshfeld-Cytron J, Goldman K, Pavone ME, Gerber S, Klock SC. Correlation between depression, anxiety, and nausea and vomiting during pregnancy in an in vitro fertilization population: a pilot study. J Psychosom Obstet Gynaecol 2011;32:113-8.
76. Järnfelt-Samsioe A, Samsioe G, Velinder GM. Nausea and vomiting in pregnancy--a contribution to its epidemiology. Gynecol Obstet Invest 1983;16:221-9.
77. Järnfelt-Samsioe A, Eriksson B, Waldenström J, Samsioe G. Some new aspects on emesis gravidarum. Relations to clinical data, serum electrolytes, total protein and creatinine. Gynecol Obstet Invest 1985;19:174-86.
78. Jinadu MK, Daramola SM. Emotional changes in pregnancy and early puerperium among the Yoruba women of Nigeria. Int J Soc Psychiatry 1990;36:93-8.
79. Källén B, Lundberge G, Aberge A. Relationship between vitamin use, smoking and nausea and vomiting of pregnancy. Acta Obstet Gynecol Scand 2003;82:916-20.
80. Klebanoff MA, Koslowe PA, Kaslow R, Rhoads GG. Epidemiology of vomiting in early pregnancy. Obstet Gynecol 1985;66:612-6.
81. Kramer J. Nausea 1957;9:586-94.
82. Speert H, Guttmacher AF. Frequency and significance of bleeding in early pregnancy. J Am Med Assoc 1954;155:712-5.
83. Stewart J, Wheeler E, Scofield C. Regional differences in British attitudes to diet in pregnancy: priorities and pragmatism. Ecol Food Nutr 1988;20:211-29.
84. Tierson FD, Olsen CL, Hook EB. Nausea and vomiting of pregnancy and association with pregnancy outcome. Am J Obstet Gynecol 1986;155:1017-22.
85. Uddenberg N, Nilsson Å, Almgren PE. Nausea in pregnancy: psychological and psychosomatic aspects. J Psychosomat Res 1971;15:269-76.
86. Vellacott ID, Cooke EJ, James CE. Nausea and vomiting in early pregnancy. Int J Gynaecol Obstet 1988;27:57-62.
87. Walker AR, Walker BF, Jones J, Verardi M, Walker C. Nausea and vomiting and dietary cravings and aversions during pregnancy in South African women. Br J Obstet Gynaecol 1985;92:484-9.
88. Weigel MM, Weigel RM. Nausea and vomiting of early pregnancy and pregnancy outcome. An epidemiological study. BJOG: Int J Obstet Gynaecol 1989;96:1304-11.
89. Werler MM, Pober BR, Nelson K, Holmes LB. Reporting accuracy among mothers of malformed and nonmalformed infants. Am J Epidemiol 1989;129:415-21. and vomiting in pregnancy: prevalence and relationship with psychosocial determinants of health. Master of Nursing thesis, College of Nursing, University of Saskatchewan, Saskatoon, SK, 2010.
90. Kricker A, Elliott J, Forrest J, McCredie J. Congenital limb deficiency: maternal factors in pregnancy. Aust N Z J Obstet Gynaecol 1986;26:272-5.
91. Kullander S, Källén B. A prospective study of drugs and pregnancy. II. Anti-emetic drugs. Acta Obstet Gynecol Scand 1976;55:105-11.
92. Lacroix R, Eason E, Melzack R. Nausea and vomiting during pregnancy: A prospective study of its frequency, intensity, and patterns of change. Am J Obstet Gynecol 2000;182:931-7.
93. Lindseth G, Vari P. Nausea and vomiting in late pregnancy. Health Care Women Int 2005;26:372-86.
94. Little RE, Hook EB. Maternal alcohol and tobacco consumption and their association with nausea and vomiting during pregnancy. Acta Obstet Gynecol Scand 1979;58:15-7.
95. Louik C, Hernandez-Diaz S, Werler MM, Mitchell AA. Nausea and vomiting in pregnancy: maternal characteristics and risk factors. Paediatr Perinat Epidemiol 2006;20:270-8.
96. Masson GM, Anthony F, Chau E. Serum chorionic gonadotrophin (hCG), schwangerschaftsprotein 1 (SP1), progesterone and oestradiol levels in patients with nausea and vomiting in early pregnancy. Br J Obstet Gynaecol 1985;92:211-5.
97. McBride ML, Van den Steen N, Lamb CW, Gallagher RP. Maternal and gestational factors in cryptorchidism. Int J Epidemiol 1991;20:964-70.
98. Medalie JH. Relationship between nausea and/or vomiting in early pregnancy and abortion. Lancet 1957;273(6986):117-9.
99. Meyer LC, Peacock JL, Bland JM, Anderson HR. Symptoms and health problems in pregnancy: their association with social factors, smoking, alcohol, caffeine and attitude to pregnancy. Paediatr Perinat Epidemiol 1994;8:145-55.
100. Milkovich L, van den Berg BJ. An evaluation of the teratogenicity of certain antinauseant drugs. Am J Obstet Gynecol 1976;125:244-8.
101. Mori M, Amino N, Tamaki H, Miyai K, Tanizawa O. Morning sickness and thyroid function in normal pregnancy. Obstet Gynecol 1988;72(3 Pt 1):355-9.
102. O'Brien B, Zhou Q. Variables related to nausea and vomiting during pregnancy. Birth 1995;22:93-100.
103. Paarlberg KM, Vingerhoets AJ, Passchier J, Heinen AG, Dekker GA, van Geijn HP. Psychosocial factors as predictors of maternal well-being and pregnancy-related complaints. J Psychosom Obstet Gynaecol 1996;17:93-102.
104. Petitti DB. Nausea and pregnancy outcome. Birth 1986;13:223-6.
105. Robertson GG. Nausea and vomiting of pregnancy; a study in psychosomatic and social medicine. Lancet 1946;2(6419):336-41.
106. Semmens JP. Hyperemesis gravidarum evaluation and treatment. Obstet Gynecol
107. Whitehead SA, Andrews PLR, Chamberlain GVP. Characterisation of nausea and vomiting in early pregnancy: a survey of 1000 women. J Obstet Gynaecol 1992;12:364-9.
108. Wolkind S, Zajicek E. Psycho-social correlates of nausea and vomiting in pregnancy. J Psychosom Res 1978;22:1-5.
109. Yerushalmy J, Milkovich L. Evaluation of the teratogenic effect of meclizine in man. Am J Obstet Gynecol 1965;93:553-62.
110. Adams MM, Harlass FE, Sarno AP, Read JA, Rawlings JS. Antenatal hospitalization among enlisted servicewomen, 1987-1990. Obstet Gynecol 1994;84:35-9.
111. Askling J, Erlandsson G, Kaijser M, Akre O, Ekbom A. Sickness in pregnancy and sex of child. Lancet 1999;354(9195):2053.
112. Bacak SJ, Callaghan WM, Dietz PM, Crouse C. Pregnancy-associated hospitalizations in the United States, 1999-2000. Am J Obstet Gynecol 2005;192(2):592-7.
113. Bailit JL. Hyperemesis gravidarium: Epidemiologic findings from a large cohort. Am J Obstet Gynecol 2005;193(3 Pt 1):811-4.
114. Bennett TA, Kotelchuck M, Cox CE, Tucker MJ, Nadeau DA. Pregnancy-associated hospitalizations in the United States in 1991 and 1992: a comprehensive view of maternal morbidity. Am J Obstet Gynecol 1998;178:346-54.
115. Cedergren M, Brynhildsen J, Josefsson A, Sydsjö A, Sydsjö G. Hyperemesis gravidarum that requires hospitalization and the use of antiemetic drugs in relation to maternal body composition. Am J Obstet Gynecol 2008; 198(4):412.e1-5.
116. Fell DB, Dodds L, Joseph KS, Allen VM, Butler B. Risk factors for hyperemesis gravidarum requiring hospital admission during pregnancy. Obstet Gynecol 2006 Feb;107(2 Pt 1):277-84.
117. Fischer-Rasmussen W, Kjaer SK, Dahl C, Asping U. Ginger treatment of hyperemesis gravidarum. Eur J Obstet Gynecol Reprod Biol 1990;38:19-24.
118. Fitzgerald JPB. Epidemiology of hyperemesis gravidarum. Lancet 1956: I (May 12):660-2.
119. Gazmararian JA, Petersen R, Jamieson DJ, Schild L, Adams MM, Deshpande AD, Franks AL. Hospitalizations during pregnancy among managed care enrollees. Obstet Gynecol 2002; 100: 94-100.
120. Hallak M, Tsalamandris K, Dombrowski MP, Isada NB, Pryde PG, Evans MI. Hyperemesis gravidarum. Effects on fetal outcome. J Reprod Med 1996;41:871-4.
121. Jimenez V, Marleau JD. Is hyperemesis gravidarum related to country of origin? Short report. Can Fam Physician 2000;46:1607-8.
122. Källén B. Hyperemesis during pregnancy and delivery outcome: a registry study. Eur J Obstet Gynecol Reprod Biol 1987;26:291-302.
123. Matsuo K, Ushioda N, Nagamatsu M, Kimura T. Hyperemesis gravidarum in Eastern Asian population. Gynecol Obstet Invest 2007;64:213-6.
124. Reid DE, Teel HM. The treatment of the vomiting of early pregnancy. N Eng J Med 1938;218:109-13.
125. Scott CL, Chavez GF, Atrash HK, Taylor DJ, Shah RS, Rowley D. Hospitalizations for severe complications of pregnancy, 1987-1992. Obstet Gynecol 1997;90:225-9.
126. Tsang IS, Katz VL, Wells SD. Maternal and fetal outcomes in hyperemesis gravidarum. Internat. J Gynecol Obstet 1996;55:231-5.
127. Vikanes A, Grjibovski AM, Vangen S, Magnus P. Variations in prevalence of hyperemesis gravidarum by country of birth: A study of 900,074 pregnancies in Norway 1967-2005. Scand J Public Health 2008;36:135-42.
128. Gadsby R, Barnie-Adshead AM. Nausea and vomiting of pregnancy: clinical information about nausea and vomiting of pregnancy and its relation to various aspects of womens’ personal and obstetric histories and other significant factors related to nausea and vomiting of pregnancy or hyperemesis gravidarum. A literature review. Available at: http://www.pregnancysicknesssupport.org.uk/documents/NVP-lit-review.pdf
129. Koren G, Maltepe C. Pre-emptive therapy for severe nausea and vomiting of pregnancy and hyperemesis gravidarum. J Obstet Gynaecol 2004;24:530-3.
130. Koren G, Maltepe C. Preventing recurrence of severe morning sickness. Can Fam Physician 2006;52:1545-6.
131. Czeizel AE, Dudas I, Fritz G, Técsöi A, Hanck A, Kunovits G. The effect of periconceptional multivitamin-mineral supplementation on vertigo, nausea and vomiting in the first trimester of pregnancy. Arch Gynecol Obstet 1992;251:181-5.
132. Koren G, Clark S, Hankins GD, et al. Effectiveness of delayed-release doxylamine and pyridoxine for nausea and vomiting of pregnancy: a randomized placebo controlled trial. Am J Obstet Gynecol 2010;203(6):571.e1-7.