Epidemiology of nausea and vomiting of pregnancy: prevalence, severity, determinants, and the importance of race/ethnicity

A prospective study including pregnant women attending the Centre Hospitalier Universitaire (CHU) Sainte-Justine or René-Laennec clinics for their prenatal care was conducted from 2004 to 2006. Women were eligible if they were ≥ 18 years of age, and ≤ 16 weeks of gestation. Women were asked to fill out a 1st trimester self-administered questionnaire and were interviewed over the telephone during their 2nd trimester of pregnancy. Presence of nausea and vomiting of pregnancy was based on the reporting of pregnant women (yes/no); severity of symptoms was measured by the validated modified-PUQE index.Of the 367 women included in the study, 81.2% were Caucasians, 10.1% Blacks, 4.6% Hispanics, and 4.1% Asians. Multivariate analyses showed that race/ethnicity was significantly associated with a decreased likelihood of reporting nausea and vomiting of pregnancy (Asians vs. Caucasians OR: 0.13; 95%CI 0.02–0.73; and Blacks vs. Caucasians OR: 0.29; 95%CI 0.09–0.99).Our study showed that race/ethnicity was associated with the reporting of nausea and vomiting of pregnancy in the 1st trimester of pregnancy.Fifty to ninety percent of pregnant women experience nausea and vomiting during their first trimester [1]. In general nausea and vomiting of pregnancy (NVP) appear between the 4th and 6th week of gestational age, with a peak observed between week 8 and 12 [2,3]. A more severe form of NVP, known as hyperemesis gravidarum (HG), will also occur in 0.5 to 3 percent of pregnancies and may lead to hospitalisation [4,5]. The aetiology of NVP is poorly understood but NVP could be considered as a multifactorial problem. Proposed theories involve hormonal, vestibular system, gastrointestinal, psychological, hyperolfaction, genetic, and evolutionary factors as possible causes [6,7].Studies that contributed to the epidemiology of NVP have reported conflicting findings, and often failed to account for all possible co-variables necessary to evaluate the multidimensional associations [8-12].