WIC participation and prenatal care are associated with reduced risk of low birthweight for Black mothers with Medi-Cal coverage in San Francisco (SF): A county birth certificate analysis

Black infants in SF have twice the risk of low birthweight (LBW) compared to other infants (12.2% vs. 6.9%). To determine if the elevated risk is associated with lack of Women Infants and Children Supplemental Nutrition (WIC) services and/or limited prenatal care (PNC), this cross-sectional study evaluated data from the Birth Statistical Master File on singleton live-births to Black mothers who were resident in SF in 2009 or 2010 and had Medi-Cal coverage (n=534). Multivariable logistic regression models were used to estimate the relative odds of LBW associated with WIC participation and/or PNC, controlling for maternal age, education, pre-pregnancy weight status, smoking, parity, and timing of PNC. 68% of mothers participated in WIC and had 7 or more PNC visits; The LBW rate for these mothers was comparable to the citywide average (7.4%). The 10% of mothers who did not participate in WIC, but had 7+ PNC visits had a LBW rate of 12.5%. The 17% of mothers who participated in WIC but had <7 PNC visits had a LBW rate of 15.7%. The 4% of mothers who did not participate in WIC and had <7 PNC visits had a LBW rate of 50%, 14 times higher than those who had accessed services (OR 14.1, 95%CI: 4.9-40.6). WIC participation and PNC are associated with reduced LBW risk for at-risk mothers in SF. The analysis did not control for social determinants of health. Further work is needed to identify risk factors for women who do not access services.