Small-for-Gestational-Age Births are Associated with Maternal Relationship Status: A Population-Wide Analysis.

Objectives To examine the association between maternal relationship status during pregnancy and infant birth outcomes. Methods Observational study of the National Longitudinal Survey of Youth 1979, a nationally representative sample of 12,686 men and women between the ages of 14 and 21. We used data from surveys of women reporting childbirth between 1979 and 2004. Relationship status was defined as relationship with an opposite-sex partner in the child's birth year. Relationship stability was defined as the consistency in relationship status in the 1 year before, of, and after the child's birth. Childbirth outcome included small-for-gestational age (SGA) infant. We applied random effects logistic regression models to assess the association between relationship status and stability and childbirth outcome-adjusting for maternal race, infant sex, history of miscarriage, employment, maternal age, multiparity, cohort-entry year, household poverty status, and tobacco use. Results The study included 4439 women with 8348 live births. In fully adjusted models, term SGA infants were more commonly born to partnered women (AOR 1.81; 95 % CI 1.20-2.73) and unmarried women (AOR 1.82; CI 1.34-2.47; LRT p value 0.0001), compared to married women. SGA infants were also more commonly born in unstable relationships (AOR 1.72; 95 % CI 1.14-2.63; LRT p value 0.01) compared to stable relationships. Conclusions for Practice Maternal relationship status and stability during pregnancy is independently associated with risk of SGA infant birth.