Nausea and vomiting in early pregnancy were associated with a substantially reduced risk of pregnancy loss in a prospective preconception cohort of almost 800 pregnant women.
Although there has long been the suggestion that nausea is a sign of a healthy pregnancy, the evidence supporting this idea has been limited.
“Much of the published literature reports on studies that enrolled women after a clinically recognized pregnancy, thereby failing to include women with early pregnancy losses or relying on participant recall of nausea and/or loss,” wrote Stefanie N. Hinkle, PhD, of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Md., and her colleagues.
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In this study, the researchers examined data from 797 women with one or two prior pregnancy losses and a current pregnancy confirmed by an HCG pregnancy test. They all were enrolled in a randomized clinical trial on the effects of aspirin on gestation and reproduction (JAMA Intern Med. 2016 Sep 26. doi: 10.1001/jamainternmed.2016.5641).
Participants kept a daily record of nausea and vomiting symptoms for gestational weeks 2-8 and then monthly after that. At week 12, 86% of the women reported nausea and 35% reported nausea with vomiting at least once a week in the previous 4 weeks.
Overall, women with nausea and vomiting in any given week had a 75% lower risk of pregnancy loss during that week (hazard ratio, 0.25), while those with only nausea had a 50% reduction in pregnancy loss (HR, 0.50), compared with women with neither symptom.
For women who had a peri-implantation pregnancy loss, the researchers found a similar association but it did not reach statistical significance. The hazard ratio was 0.59 for women who had nausea only and 0.51 for women who experienced nausea with vomiting.
Among women who did not experience a peri-implantation pregnancy loss, nausea only and nausea with vomiting were associated with a 66% (HR, 0.44) and 80% (HR, 0.20) reduction in risk for pregnancy loss, respectively, compared with women with neither symptom. These reductions in risk were similar when the analysis was limited to first-trimester pregnancy loss and persisted even after accounting for lifestyle and fetal factors, such as number of prior pregnancy losses, body-mass index, fetal karyotype, and multiple fetal gestations.
“These findings overcome prior analytic and design limitations and represent the most definitive data available, to our knowledge, indicating the protective association of nausea and vomiting in early pregnancy on the risk for pregnancy loss and thus may provide reassurance to women experiencing these difficult symptoms in pregnancy,” researchers wrote.
The study was supported by the National Institutes of Health. The researchers reported having no financial disclosures.