title: Prevalence of nausea and vomiting of pregnancy in the USA: a meta analysis.
abstract: BACKGROUND
  Nausea and vomiting of pregnancy (NVP) is the most common medical condition during gestation, carrying tremendous health burden, especially for the severe form, hyperemesis gravidarum (HG). The rates of NVP in the USA have not been systematically calculated.
  
  
  OBJECTIVE
  To estimate the rates of NVP and HG in the USA.
  
  
  METHODS
  A meta-analysis was conducted of all peer-reviewed articles from the USA that provided rates of NVP in early or late pregnancy or HG. Medline, Embase and Cochrane databases were searched from inception through November 2012; reviews and articles were hand searched. Rates were combined across studies using a random effects model.
  
  
  RESULTS
  Forty-eight articles were identified; 15 were rejected and 33 were included for analysis. Twenty-three studies of 67,602 women provided rates of NVP which had a meta-analytic rate of 68.6% (CI95%:64.4%-72.8%). Three of them (N=5034) reported nausea without vomiting in 28.6% and two studies (N=136) produced a rate for NVP during late pregnancy of 24.0%. HG occurred in 1.2% of the 2.1 million women in 12 studies.
  
  
  CONCLUSIONS
  We have summarized rates of NVP and HG, which are similar to those found in other parts of the world. Almost 70% of women suffer some form of the syndrome; 1.2% have the severe form, most of whom were hospitalized because of the HG. Future research should address issues of cost and resource utilization.
authors.affiliation: Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Canada. t.einarson@rogers.com
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Einarson
authors.forename: Charles
authors.initials: C
authors.lastname: Piwko
authors.forename: Gideon
authors.initials: G
authors.lastname: Koren
mesh_terms: D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D006939:Hyperemesis Gravidarum / Q000453:epidemiology*; D048968:Morning Sickness / Q000453:epidemiology*; D011247:Pregnancy; D015995:Prevalence; D012720:Severity of Illness Index; D014481:United States / Q000453:epidemiology