Risk factors for hyperemesis gravidarum requiring hospital admission during pregnancy

OBJECTIVE: To identify risk factors for hyperemesis requiring hospital admission during pregnancy. METHODS: Data from a population-based cohort of all deliveries in Nova Scotia, Canada between 1988 and 2002 were obtained from the Nova Scotia Atlee Perinatal Database. Women with 1 or more antepartum admissions for hyperemesis were compared with women with no admissions for hyperemesis. Relative risks (RRs) and 95% confidence intervals (CIs) were estimated using logistic regression and used to determine a set of independent risk factors for hyperemesis. RESULTS: The overall rate of admission for hyperemesis was 0.8% (n = 1,301) among 157,922 deliveries. In the adjusted analysis, hyperthyroid disorders (RR 4.5, 95% CI 1.8-11.1), psychiatric illness (RR 4.1, 95% CI 3.0-5.7), previous molar pregnancy (RR 3.3, 95% CI 1.6-6.8), preexisting diabetes (RR 2.6, 95% CI 1.5-4.7), gastrointestinal disorders (RR 2.5, 95% CI 1.8-3.6), and asthma (RR 1.5, 95% CI 1.2-1.9) were all statistically significant risk factors for hyperemesis, whereas maternal smoking and maternal age older than 30 were associated with decreased risk. Compared with singleton male pregnancies, singleton female pregnancies, pregnancies with multiple male fetuses, and male and female combinations were associated with statistically significant increased risk of hyperemesis. CONCLUSION: Although hospitalization for hyperemesis occurs in less than 1% of pregnant women, this translates to a large number of hospital admissions. The factors associated with hyperemesis are primarily medical and fetal factors that are not easily modifiable, but identification of these factors may be useful in determining those women at high risk for developing hyperemesis.