Infant mortality and the risk of small size for gestational age in the subsequent pregnancy: a retrospective cohort study.

To examine the association between prior infant mortality and subsequent risk for small for gestational age (SGA). This population-based, retrospective cohort study used the Missouri maternally linked, longitudinal dataset (1989-2005). Analyses were restricted to women who had two singleton pregnancies during the study period. Logistic regression was conducted to obtain adjusted odds ratios (AOR) and 95 % confidence intervals (CI) for the association between infant mortality in the first pregnancy and SGA in the second pregnancy. Women with a prior occurrence of infant death were more likely to be black and obese and had lower educational levels and had higher rates of pregnancy-related complications (p < 0.01). White women with previous infant mortality were at 1.46 times greater risk for SGA in the subsequent pregnancy (AOR = 1.46, 95 % CI = 1.24-1.71). For black women with prior infant death, the risk for SGA increased to 2.77 times (AOR = 2.77, 95 % CI = 2.19-3.51). White mothers who experienced infant mortality coupled with SGA in the first pregnancy had a nearly threefold heightened risk for SGA in the second pregnancy (AOR = 2.89, 95 % CI = 2.21-3.78), whereas black women with this history were more than four times as likely to have an infant with SGA (AOR = 4.60 95 % CI = 3.05-6.96). Prior occurrence of infant mortality is associated with increased risk for subsequent SGA. This finding has important implications for health professionals, as targeted inter-conception strategies for women who have experienced infant death, as well as SGA, may be warranted.