title: Severity and duration of nausea and vomiting symptoms in pregnancy and spontaneous abortion.
abstract: BACKGROUND
  Earlier studies have shown an inverse association between the presence of nausea and vomiting in pregnancy (NVP) and spontaneous abortion (SAB), but no study to date has examined the effects of symptom duration on the risk of SAB.
  
  
  METHODS
  We examined NVP symptom severity and duration in relation to the occurrence of SAB. Data were collected from 2407 pregnant women in three US cities between 2000 and 2004 through interviews, ultrasound assessments and medical records abstractions. Discrete-time continuation ratio logistic survival models were used to examine the association between NVP and pregnancy loss.
  
  
  RESULTS
  Lack of NVP symptoms was associated with increased risk for SAB [adjusted odds ratio (OR) = 3.2, 95% confidence interval (CI): (2.4, 4.3)], compared with having any symptoms. Reduced risks for SAB were found across most maternal age groups for those with NVP for at least half of their pregnancy, but the effects were much stronger in the oldest maternal age group [OR = 0.2, 95% CI: (0.1, 0.8)].
  
  
  CONCLUSIONS
  The absence of NVP symptoms is associated with an increased risk of early pregnancy loss. As symptom duration decreases, the likelihood of early loss increases, especially among women in the oldest maternal age group.
authors.affiliation: Department of Maternal and Child Health, School of Public Health, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7435, USA. ronna@email.unc.edu
authors.forename: Ronna L
authors.initials: RL
authors.lastname: Chan
authors.forename: Andrew F
authors.initials: AF
authors.lastname: Olshan
authors.forename: David A
authors.initials: DA
authors.lastname: Savitz
authors.forename: Amy H
authors.initials: AH
authors.lastname: Herring
authors.forename: Julie L
authors.initials: JL
authors.lastname: Daniels
authors.forename: Herbert B
authors.initials: HB
authors.lastname: Peterson
authors.forename: Sandra L
authors.initials: SL
authors.lastname: Martin
mesh_terms: D000022:Abortion, Spontaneous / Q000209:etiology*; D000328:Adult; D005260:Female; D006801:Humans; D016015:Logistic Models; D008423:Maternal Age; D009325:Nausea / Q000150:complications*; D011247:Pregnancy; D011248:Pregnancy Complications; D011446:Prospective Studies; D012306:Risk; D014839:Vomiting / Q000150:complications*