Intergenerational Risk for Preterm Birth by Race/Ethnicity

Women who were born prematurely themselves are more likely to deliver prematurely. However, much of the evidence establishing intergenerational risk has focused on white women. We didn’t know if increased risk for delivering prematurely was consistent across racial/ethnic groups. Risk factors are important to understand by race, as the stark reality of preterm birth in California is one of health inequity. While 1 in 12 babies are born too soon, the rate of preterm birth among Black women is 47 percent higher than the rate among all other women. Understanding if intergenerational risk is consistent for Black and Brown families will help us identify women at higher risk of preterm birth, and influence policies and treatment recommendations.

In this study, we looked at the likelihood a woman would have a preterm birth based on whether she was born preterm, and then examined risk by her race or ethnicity, poverty level, and if she had other health problems like diabetes or high blood pressure. 

We examined a large sample- 380,542 women- who had a baby between 2005 and 2011 in California, and established that women who were born preterm are at higher risk of having a preterm birth regardless of race/ethnicity. Women who were born 9 or more weeks early were at especially high risk of having preterm birth. Among women born preterm, women who had hypertension, or whose mother had hypertension while pregnant with them, were at higher risk of preterm birth regardless of their race/ethnicity. Factors indicating that they were low income or their mother was low income when pregnant with them (age at delivery, neighborhood poverty, lower neighborhood education, public health insurance) did not increase their risk of preterm birth – nor did factors like how many babies they have had, if they had anemia, or if they had diabetes. 

This research helps us to piece together what risk for prematurity looks like. The gestational age of birth for a pregnant woman can help us identify women at higher risk of preterm birth. 

Research Publication

Read the full study from American Journal of Perinatology August 2018, here: Cross-Generational Contributors to Preterm Birth in California: Singletons Based on Race/Ethnicity.