A Longitudinal Study of Changes in Prenatal Care Utilization Between First and Second Births and Low Birth Weight.

Abstract

Because previous analyses of prenatal care (PNC) utilization and risk of low birth weight (LBW) may have been influenced by selection bias, we conducted a study using longitudinal data of women with repeat pregnancies. We analyzed Washington State birth certificates of first and second live births (2003-2012). We estimated relative risk (RR) of LBW at second birth associated with Kotelchuck Index PNC level among women stratified by level of PNC in their first birth (n = 67,571). Among women with inadequate PNC prior to their first birth (n = 10,355), women with intermediate or adequate PNC before their second birth (n = 7464) had a reduced risk of LBW (adjusted RR 0.61, 95% CI: 0.48, 0.78) compared to those whose PNC level remained inadequate. Likewise, among women with intermediate or adequate PNC prior to their first birth (n = 57,216), those with inadequate PNC before the second birth (n = 7095) had higher risk of LBW (adjusted RR 1.59, 95% CI: 1.36, 1.85) compared to those who remained at intermediate or adequate PNC. Our findings support the hypothesis that PNC decreases LBW risk at second birth, independent of factors related to the utilization of PNC at first birth.