Objective To evaluate whether the expansion of Federally Qualified Health Centers (FQHCs) improved late prenatal care initiation, low birth weight, and preterm birth among Medicaid-covered or uninsured individuals.

Data Sources and Study Setting We identified all FQHCs in California using the Health Resources and Services Administration's Uniform Data System from 2000 to 2019. We used data from the U.S. Census American Community Survey to describe area characteristics. We measured outcomes in California birth certificate data from 2007 to 2019.

Study Design We compared areas that received their first FQHC between 2011 and 2016 to areas that received it later or that had never had an FQHC. Specifically, we used a synthetic control with a staggered adoption approach to calculate non-parametric estimates of the average treatment effects on the treated areas. The key outcome variables were the rate of Medicaid or uninsured births with late prenatal care initiation (>3 months' gestation), with low birth weight (<2500 grams), or with preterm birth (<37 weeks' gestation).

Data Collection/Extraction Methods The analysis was limited to births covered by Medicaid or that were uninsured, as indicated on the birth certificate.

Principal Findings The 55 areas in California that received their first FQHC in 2011–2016 were more populous; their residents were more likely to be covered by Medicaid, to be low-income, or to be Hispanic than residents of the 48 areas that did not have an FQHC by the end of the study period. We found no statistically significant impact of the first FQHC on rates of late prenatal care initiation (ATT: −10.4 [95% CI −38.1, 15.0]), low birth weight (ATT: 0.2 [95% CI −7.1, 5.4]), or preterm birth (ATT: −7.0 [95% CI −15.5, 2.3]).

Conclusions Our results from California suggest that access to primary and prenatal care may not be enough to improve these outcomes. Future work should evaluate the impact of ongoing initiatives to increase access to maternal health care at FQHCs through targeted workforce investments.