Morning Sickness? Count Your Blessings

Women who had nausea and vomiting or nausea alone were less likely to miscarry.

Morning sickness is considered one of the classic signs of pregnancy for women. Turns out that’s probably a good thing.

Tummy of a pregnant woman with her hands slightly above her belly

Researchers from the National Institutes of Health (NIH) found that women who had either nausea alone or nausea and vomiting had a much lower risk of miscarriage than women who didn’t have those symptoms.

Although the cause of morning sickness is not well-known, some scientists have suggested that it makes women less likely to eat foods that may be contaminated with disease-causing organisms. Morning sickness may also be a way to protect the fetus from exposure to toxins in the first three months when the risk of birth defects is highest.

In most women, morning sickness subsides by the fourth month of pregnancy. Some, however, continue to have morning sickness throughout the pregnancy.

Lead author Stefanie N. Hinkle, PhD, said in a press release, “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. 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.”

Dr. Hinkle is an epidemiologist and staff scientist in NICHD’s Epidemiology Branch.

Dr. Hinkle and colleagues used data collected in the Effects of Aspirin in Gestation and Reproduction (EAGeR) trial.

All the study participants had previously experienced one or two miscarriages. Of the 797 women in the trial, 181 experienced another miscarriage during the trial.

The women in the trial kept daily diaries of symptoms for the first eight weeks of the pregnancy and then completed monthly questionnaires through week 36. Previous studies had not obtained such detailed data and instead relied on women’s recollections of symptoms much later in their pregnancies.

Dr. Hinkle and team found that 57.3 percent of the women in the study reported nausea alone, while 26.6 reported nausea and vomiting. Both groups were 50 to 75 percent less likely to have a miscarriage compared to those women who had no symptoms of morning sickness.

The study was published in the Nov. issue of JAMA Internal Medicine.

Information about study funding and conflict of interest was not available.

Cornell University, “Morning sickness linked to lower risk of pregnancy loss”
JAMA Internal Medicine, “Association of Nausea and Vomiting During Pregnancy With
Pregnancy Loss: A Secondary Analysis of a Randomized Clinical Trial”

Written by: Beth Greenwood, RN | Medically reviewed by: Dr. Robert Carlson, M.D.