Objective: To identify risk factors for hyperemesis gravidarum, a severe form of nausea and vomiting that occurs in early pregnancy.
Study Design: A systematic review used pre-defined eligibility criteria and a search of PubMed, CINAHL, ISI Web of Knowledge, and PsycINFO to identify original research articles (from any country, study year, and publication language and year) that examined risk factors for hyperemesis gravidarum. Information about the study design, population, and results of each of the forty-three included studies were extracted and compared.
Results: Low pre-pregnancy weight, Helicobacter pylori infection, a history of hyperemesis gravidarum in a previous pregnancy, and carrying a female fetus appear to be risk factors for hyperemesis gravidarum. The associations between hyperemesis gravidarum and maternal age, gravidity, and parity, are not yet well defined.
Conclusion: Additional studies are needed to evaluate the association between hyperemesis gravidarum and ethnicity, socioeconomic status, mental and physical health, and other understudied characteristics.
Keywords: Hyperemesis gravidarum, risk factors, systematic review, nausea, vomiting, pregnancy, Helicobacter pylori, dehydration, International Classification of Disease, Wernicke's encephalopathy, pontine myeli-nolysis, vasospasm, cerebral arteries, splenic avulsion, esophageal rupture, pneumothorax, liver dysfunction, psychosomatic disorder, p-value, tobacco, Demographic, nulliparity, gastrointestinal diseases, hyperthyroid, ulcers, asthma, respiratory diseases, Hypertension, Diabetes, hyperemesis, estrogens, thyroid hormones