Quantifying the global rates of nausea and vomiting of pregnancy: A meta-analysis

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% (CI_95%: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% (CI_95%: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%.