Is limited access to obstetric services associated with adverse birth outcomes? A cross-sectional study of Korean national birth data

OBJECTIVES: The geographical disparity in the access to essential obstetric services is a public health issue in many countries. We explored the association between timely access to obstetric services and the individual risk of adverse birth outcomes. DESIGN: Repeated cross-sectional design. SETTING: South Korean national birth data linked with a medical service provision database. PARTICIPANTS: 1 842 718 singleton livebirths from 2014 to 2018. PRIMARY OUTCOME MEASURES: Preterm birth (PTB), post-term birth, low birth weight (LBW) and macrosomia. RESULTS: In the study population, 9.3% of mothers lived in districts where the Time Relevance Index (TRI) was as low as the first quartile (40.6%). Overall PTB and post-term birth rates were 5.0% and 0.1%, respectively. Among term livebirths, LBW and macrosomia occurred in 1.0% and 3.3%, respectively. When the TRI is lower, representing less access to obstetric care, the risk of macrosomia was higher (adjusted OR=1.15, 95% CI 1.11 to 1.20 for Q1 compared with Q4). Similarly, PTB is more likely to occur when TRI is lower (1.05, 95% CI 1.00 to 1.10 for Q1; 1.03, 95% CI 1.01 to 1.05 for Q2). There were some inverse associations between TRI and post-term birth (0.80, 95% CI 0.71 to 0.91, for Q2; 0.84, 95% CI 0.76 to 0.93, for Q3). CONCLUSIONS: We observed less accessibility to obstetric service is associated with higher risks of macrosomia and PTB. This finding supports the role of obstetric service accessibility in the individual risk of adverse birth outcomes.