P3.B026: Mother's Own Milk Provision Over the First 12 Weeks of Life by Gestational Age in a U.S. Cohort

Background: Exclusive mother’s own milk (MOM) through 6 months of age is recommended due to the known protective factors against diseases and improved developmental outcomes in infancy. Although MOM is also associated with reduced risk of neonatal complications, there are no population-based studies in the United States reporting longitudinal rates of MOM feedings based on gestational age (GA) at birth. Our objective was to compare rates of MOM provision at 12 weeks of life based on infants GA at birth.

Methods: Data provided by the 2021 Pregnancy Risk Assessment Monitoring System (PRAMS) from 36 U.S. jurisdictions (33 states, the District of Columbia, New York City, and Puerto Rico) were used for analysis (n=29098). Data were weighted to reflect the relative populations of each state prior to conducting analyses. Infants were categorized by birth GA ( < 27 weeks, 28-33 weeks, 34-36 weeks, 37+ weeks). Maternal characteristics included race/ethnicity, age, insurance, education, marital status, WIC use during pregnancy, delivery characteristics (mode, singleton/multiple), pre-pregnancy body mass index and cigarette smoking. Rates of MOM initiation and continued MOM provision at 12 weeks conditional on initiation were then compared between GA groups. Population-weighted multivariable logistic regression models were used to examine the association between MOM outcomes and GA at birth, controlling for maternal characteristics. Adjusted predictions and marginal effects were calculated for GA groups. SAS version 9.4 and STATA version 17 were used for statistical analyses.

Results: Sample characteristics differed significantly across GA groups. The highest rates of MOM feeding initiation were found at the lowest GA category ( < 27 weeks). Late preterm infants (34-36 weeks) had the lowest rate of initiation at 81.8% (95% CI, 79.5-84.1) (Table 1). MOM provision at 12 weeks conditional on initiation was highest in term (37+ weeks) infants at 71.6% (95% CI, 70.7-72.6) (Table 1). After adjusting for maternal characteristics, the late preterm population was 4.4 percentage points less likely to initiate MOM feeding (95%CI, -6.7 to -2.1) and 6.7 percentage points less likely to continue MOM provision at 12 weeks postpartum (95% CI, -9.9 to -3.5) compared to term infants (Table 2).

Conclusion: MOM feeding initiation rates were lowest in the late preterm group. Adjusted analyses revealed significantly lower sustained MOM provision at 12 weeks for late preterm infants compared to term peers. This demonstrates a need for further outreach, education, and lactation support for mothers of late preterm infants to both improve infant and maternal health and increase the likelihood of reaching national and international breastfeeding goals in this vulnerable population of infants.