Morning sickness. It’s no fun for pregnant women.
But new research shows strong evidence that the nausea and vomiting known as “morning sickness” indicates that there’s a reduced chance that a pregnant woman will have a miscarriage. “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,” says Stefanie Hinkle, Ph.D. at the National Institute’s Institute of Child Health and Human Development. “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.”
Morning sickness may protect the fetus
The nausea and vomiting that occurs in pregnancy usually begin in the morning and they ease as the day progresses. For most women, those problems subside by the 4th month of pregnancy. Others may have these symptoms for the duration of their pregnancies. The cause of morning sickness is not known, but researchers have theorized that it protects the fetus against toxins and disease-causing organisms in foods and beverages.
For their study, Dr. Hinkle and her colleagues analyzed data from a research trial intended to study whether taking daily low-dose aspirin could help prevent a miscarriage. The pregnant women in that study kept daily diaries of whether they experienced nausea and vomiting in the 2nd through the 8th week of their pregnancies. After that the women responded to a monthly questionnaire about their symptoms through the 36th week of pregnancy.
In the aspirin trial, a total of 797 women had positive pregnancy tests, with 188 pregnancies ending in loss. By the 8th week of pregnancy, 57.3 percent of the women reported experiencing nausea and 26.6 percent reported nausea with vomiting. The researchers found that these women were 50 to 75 percent less likely to experience a pregnancy loss, compared to those who had not experienced nausea alone or nausea accompanied by vomiting.
Most detailed study yet
Dr. Hinkle says 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. “Our study confirms that there is a protective association between nausea and vomiting and a lower risk of pregnancy loss,” she says.