June 18, 2019

Research funded by the March of Dimes and published today in the Journal of Perinatology found that non-Hispanic Black women and non-Hispanic white women can both benefit from spacing their pregnancies to prevent premature birth. The new study was led by the March of Dimes Prematurity Research Center at Stanford University School of Medicine,

“We’ve known for some time that short interpregnancy interval (IPI) is a risk factor for preterm birth, but we needed ‘within-mother’ studies of more diverse populations before drawing firm conclusions about the importance of birth spacing for both non-Hispanic Black and non-Hispanic white women. And now we have such a study,” says Kelle H. Moley, M.D., Chief Scientific Officer for March of Dimes.

“In within-mother studies, women act as their own controls, thereby reducing confounding by other factors known to be associated with preterm birth. Now we can speak confidently about the importance of birth spacing to both non-Hispanic Black and non-Hispanic white women,” Dr. Moley says.

March of Dimes advises that women wait at least 18 months (1½ years) between giving birth and getting pregnant again. “This much time gives your body time to fully recover from your last pregnancy before it’s ready for your next pregnancy,” Dr. Moley explains.  “We don’t know exactly why getting pregnant again too soon increases your chances of premature birth and other health problems for your baby, but it may be because your body needs time to build up its supply of nutrients, heal from infection and inflammation, or reset the microbiome of the vagina (birth canal).” Dr. Moley notes that March of Dimes supports research to learn more about the vaginal microbiome and premature birth.

Pregnancies that start too soon after the previous birth are associated with delayed prenatal care and adverse birth outcomes, including preterm birth, neonatal morbidity, and low birthweight. Further, these poor birth outcomes are often associated with ongoing health problems such as developmental delay, asthma, and vision and hearing loss. In the United States, between 2006 and 2010, about one-third of pregnancies among women with a previous live birth began less than 18 months after the prior birth, placing mothers and infants at risk for adverse health outcomes.

March of Dimes supports access to preconception and prenatal care, including birth control counseling, education and services, to ensure proper birth spacing and reduce rates of preterm birth and other adverse birth outcomes. March of Dimes urges every woman to consult with a health care provider to select an approach to family planning and birth spacing consistent with her needs and beliefs.

“Short interpregnancy interval as a risk factor for preterm birth in non-Hispanic Black and White women in California” by Julia A. Lonhart, MD, Jonathan A. Mayo, MPH, Amy M. Padula PhD, Paul H. Wise, MD, David K. Stevenson, MD, and Gary M. Shaw DrPH, appeared in the Journal of Perinatology.