ORIGINAL ARTICLE Reproductive epidemiology
Severity and duration of nausea and
vomiting symptoms in pregnancy and
Ronna L. Chan1,2,*, Andrew F. Olshan2,3, David A. Savitz4,5,
Amy H. Herring3,6, Julie L. Daniels1,2, Herbert B. Peterson1,7,
and Sandra L. Martin1
1Department of Maternal and Child Health, School of Public Health, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599,
USA2Department of Epidemiology, School of Public Health, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
3Carolina Population Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA4Department of Preventive
Medicine, Mount Sinai School of Medicine, New York, NY 10029, USA5Present address: Department of Community Health, Department of
Obsterics and Gynecology, Brown University, Providence, RI 02912, USA6Department of Biostatistics, School of Public Health, The
University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA7Department of Obstetrics and Gynecology, School of Medicine,
The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
*Correspondence address. Department of Epidemiology, Gillings School of Global Public Health, The University of North Carolina at Chapel
Hill, CB# 7435, McGavran-Greenberg Hall, Chapel Hill, NC 27599-7435, USA. Tel: +1-919-843-0441; E-mail: firstname.lastname@example.org
Submitted on January 5, 2010; resubmitted on August 6, 2010; accepted on August 27, 2010
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) ¼ 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 ¼ 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.
Key words: spontaneous abortion / miscarriage / nausea and vomiting / pregnancy
Nausea and vomiting in early pregnancy (NVP) affects 50–90% of
women (Klebanoff et al., 1985; Klebanoff and Mills, 1986; Tierson
et al., 1986; Lacroix et al., 2000; Chan et al., 2009) and is commonly
the earliest symptom of pregnancy. Severity of symptoms, timing of
symptom onset and duration vary both among women and across
multiple pregnancies of a woman. Symptoms can begin as early as
2–4 weeks’ gestation (Gadsby et al., 1993; Lacroix et al., 2000) and
commonly resolve by 20 weeks’ gestation (Gadsby et al., 1993; Brous-
sard and Richter, 1998), but may continue to affect up to 20% of
women beyond 20 weeks’ gestation (Broussard and Richter, 1998).
The pathogenesis of NVP is poorly understood, but has been attrib-
uted to rises in the serum levels of human chorionic gonadotrophin
(hCG) and estrogen (Jarnfelt-Samsioe et al., 1983; Cunningham
et al., 2005). A number of maternal characteristics, including primipar-
ity (Bashiri et al., 1995), younger maternal age (Klebanoff et al., 1985;
Bashiri et al., 1995) and lower education (Klebanoff et al., 1985) have
been associated with NVP, and higher maternal BMI has been ident-
ified as a risk factor for vomiting (Klebanoff et al., 1985).
Spontaneous abortion (SAB) is defined as a pregnancy loss before
20 completed weeks’ gestation. While ?10–14% of all clinically
recognized pregnancies result in SAB (Wilcox et al., 1985; Wilcox,
2010), the actual rate of pregnancy loss, as shown with the use of bio-
chemical assays, is actually two to five times higher (Ellish et al., 1996;
Forbes, 1997; Wilcox et al., 1999). Current knowledge on causes of
early pregnancy loss is limited, but two consistent risk factors are
older maternal age and history of previous pregnancy loss (Andersen
& The Author 2010. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved.
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Human Reproduction, Vol.25, No.11 pp. 2907–2912, 2010
Advanced Access publication on September 22, 2010doi:10.1093/humrep/deq260
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