More than one day of early-pregnancy bleeding linked to lower birthweight

Wednesday, May 9, 2018

NIH study cautions that more research is needed to determine if this small difference in weight poses a health risk

Women who experience vaginal bleeding for more than one day during the first trimester of pregnancy may be more likely to have a smaller baby, compared to women who do not experience bleeding in the first trimester, suggest researchers at the National Institutes of Health. On average, full-term babies born to women with more than one day of bleeding in the first trimester were about 3 ounces lighter than those born to women with no bleeding during this time. Additionally, infants born to women with more than a day of first trimester bleeding were roughly twice as likely to be small for gestational age, a category that includes infants who are healthy but small, as well as those whose growth has been restricted because of insufficient nutrition or oxygen or other causes.

The study appears in Obstetrics & Gynecology and was conducted by researchers at the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) and other U.S. research institutions.

The authors caution that the decrease in birthweight of infants born to women with vaginal bleeding was small. More studies are needed to determine if these infants are at risk for any additional health risks in infancy or later in life.

“The good news is that only one day of bleeding was not significantly associated with reduced growth,” said the study’s senior author, Katherine L. Grantz, M.D., an investigator in the NICHD Epidemiology Branch. “But our results suggest that even if bleeding stops before the second trimester, a pregnancy with more than one day of bleeding is at somewhat of a greater risk for a smaller baby.”