Maternal marital status and the risk of stillbirth and infant death: a population-based cohort study on 40 million births in the United States.

OBJECTIVE

The objective of our study was to evaluate the association between maternal marital status and the risk of fetal and infant death, including sudden infant death syndrome (SIDS).

METHODS

We conducted a population-based cohort study using the Centers for Disease Control and Prevention's Linked Birth-Infant Death and Fetal Death data on all births in the United States between 1995 and 2004. Marital status was obtained from the birth certificate. The adjusted effect of marital status on the risk of fetal and infant mortalities was estimated using unconditional logistic regression analysis.

RESULTS

The cohort consisted of 40,529,306 births, of which 37,461,715 met study criteria. There were 130,353 stillbirths (3.5/1,000 births) and 140,175 infant deaths (3.8/1,000 births), of which 24,066 were due to SIDS (0.6/1,000 births). Rates of nonmarital births increased from 31.3% to 35.4% over the study period. As compared with births from married women, births from unmarried women were at an increased risk of stillbirths (relative rise [RR], 1.24; 95% confidence interval [CI], 1.21-1.26), total infant deaths (RR, 1.45; 95% CI, 1.42-1.47), and SIDS (RR, 1.70; 95% CI, 1.63-1.78). Among unmarried women, those at a higher risk of fetal and infant death were women under 15 or over 40 years of age, African-American women, and those who received no prenatal care.

CONCLUSION

Nonmarital childbearing seems to be associated with an increased risk of fetal and infant death, including SIDS. Promoting access to care and targeting unmarried mothers-to-be with the goal of educating, increasing awareness, and providing resources for proper obstetrical and maternal care may be of great benefit to their pregnancies.