Unmarried mothers as a high-risk group for adverse pregnancy outcomes.

A total of 36,608 singleton births occurring to Black mothers in the District of Columbia in 1980-84 were examined. Infants of unmarried mothers had a 34 percent higher incidence of low birthweight and a 35 percent higher neonatal mortality rate than infants born to married mothers. To delineate the independent effect of marital status, a logit model was fit to 23,461 births occurring to mothers over 19 years of age. Despite controlling on maternal age, educational attainment and adequacy of prenatal care, the odds ratio for low birthweight was 1.18 for the infants of unmarried mothers. Supplemental analyses showed that if mothers were drug addicted or had their first delivery before age 18, the marital status differentials in the birthweights of their infants were no longer significant. These results indicate the importance of unmarried status as a demographic risk factor, and the need for discerning specific high-risk behaviors associated with life styles of unmarried mothers.