Health Studies

Scientists Prove Morning Sickness is a Sign of Healthy Pregnancy

As any pregnant woman will tell you, morning sickness is one of the most unpleasant side effects. But recently, scientists proved that morning sickness is actually a sign your pregnancy is going well. A team of government researchers say women who experience nausea and vomiting early in pregnancy are at reduced risk of miscarriage. The researchers followed a group of women who had in the past suffered at least one miscarriage; of those subjects, the ones who had morning sickness were 50 to 75 percent less likely to have another miscarriage.

The research confirms a common “old wives tale.” Stephanie Hinkle, a staff scientist at the National Institute of Child Health and Human Development, led the study. She says:

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.

The data was gathered from women who participated in a separate study between 2007 and 2011. That study began collecting data even before the women became pregnant, so they were able to be sure there were no very early miscarriages that went unreported.

The team thinks they’ve linked the nausea to levels of a hormone that makes sure an embryo gets firmly embedded in a woman’s uterus.

They used data from women taking part in a different study of pregnancy between 2007 and 2011.

That study started collecting information before they got pregnant — so the researchers could see even very early miscarriages that women may not have noticed if they hadn’t been in a study. By the second month of pregnancy, more than 80 percent of the women in the study had nausea or vomiting or both, they found.

Hinkle’s team believes the nausea is linked to levels of a hormone that supports the embryo in embedding firmly into the mother’s uterus. Their report was published in the Journal of the American Medical Association’s JAMA Internal Medicine. According to the report:

Among women with one or two prior pregnancy losses, nausea and vomiting were common very early in pregnancy and were associated with a reduced risk for pregnancy loss…The presence of nausea and vomiting were associated with a reduction in risk by more than half for clinical pregnancy loss.

These findings contradict those of earlier studies, but those did not have data on very early pregnancy, and relied on the patients’ memories. Approximately one quarter of the pregnancies in this study ended in miscarriage, on average at seven weeks. The researchers did not indentify the cause of the misarriages, or any cause of nausea and vomiting, other than pregnancy and hormone levels. There was one consistent pattern, however: Women younger than 25 were more likely to have morning sickness than women older than 25 years of age.

The reports adds:

Our modeling strategy accounted for smoking, alcohol and caffeine intake, and stress at each week, suggesting that the mechanism is likely not through avoidance of such substances.