A new analysis by researchers at the National Institutes of Health has provided the strongest evidence to date that morning sickness during pregnancy is associated with a lower risk of miscarriage in pregnant women.
The study, appearing in JAMA Internal Medicine, was conducted by researchers at NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) and other institutions.
While the cause of morning sickness is not known, researchers have proposed that it protects the fetus against toxins and disease-causing organisms in foods and beverages.
“It’s a common thought that nausea indicates a healthy pregnancy, but there wasn’t a lot of high-quality evidence to support this belief,” said the study’s first author, Stefanie Hinkle, a staff scientist in NICHD’s Epidemiology Branch. “Our study evaluates symptoms from the earliest weeks of pregnancy, immediately after conception, and confirms that there is a protective association between nausea and vomiting and a lower risk of pregnancy loss.”
For their study, Hinkle and her colleagues analysed data from the Effects of Aspirin in Gestation and Reproduction (EAGeR) trial, in which researchers tested whether taking daily low-dose aspirin prevents women who experienced one or two prior pregnancy losses from experiencing a future loss.
The authors looked at data from all the women in the study who had a positive pregnancy test. The women kept daily diaries of whether they experienced nausea and vomiting in the 2nd through the 8th week of their pregnancies and then responded to a monthly questionnaire on their symptoms through the 36th week of pregnancy. The study authors noted that most previous studies on nausea and pregnancy loss were not able to obtain such detailed information on symptoms in these early weeks of pregnancy. Instead, most of studies had relied on the women’s recollection of symptoms much later in pregnancy or after they had experienced a pregnancy loss.
In the EAGeR trial, a total of 797 women had positive pregnancy tests, with 188 pregnancies ending in loss. By the 8th week of pregnancy, 57.3 per cent of the women reported experiencing nausea and 26.6 per cent reported nausea with vomiting. The researchers found that these women were 50 to 75 per cent less likely to experience a pregnancy loss, compared to those who had not experienced nausea alone or nausea accompanied by vomiting.
Source: National Institutes of Health
Reference: Stefanie N. Hinkle, Sunni L. Mumford, Katherine L. Grantz, Robert M. Silver, Emily M. Mitchell, Lindsey A. Sjaarda, Rose G. Radin, Neil J. Perkins, Noya Galai, Enrique F. Schisterman.Association of Nausea and Vomiting During Pregnancy With Pregnancy Loss. JAMA Internal Medicine, 2016; DOI:10.1001/jamainternmed.2016.5641