Effect of neighborhood socioeconomic context in prenatal care and pregnancy outcomes in women delivering in Portugal

Background:Contextual conditions affect health outcomes, in specific settings and beyond individual characteristics. Measuring its effect may contribute to understand social inequalities in health. We aimed to evaluate how late prenatal care and pregnancy outcomes (preterm and small-for-gestational-age (SGA) babies) vary according the place of residence and its respective socioeconomic conditions.

Methods: We studied a population-based sample of 6255 women delivering singletons. Individual socioeconomic characteristics and gestational age at first visit (late care: >12 gestational weeks) were self-reported. Preterm (birth before 37GW) and SGA (sex-specific weight <10^thpercentile for each GW) were classified according medical records. Maternal addresses were linked with census blocks. Multilevel logistic regression models, adjusted for individual- and block-level socioeconomic conditions were used. Neighbor-to-neighbor variability was measured using median odds ratio (MOR). The effect of block socioeconomic class (poor; intermediate; rich) was assessed using 80% interval odds ratio (IOR) that integrates the fixed effects and the random variation at the area-level.

Results: The prevalence of late prenatal care, preterm and SGA were, respectively, 11%, 7% and 15%. Late care and SGA more frequently occurred among more deprived women, and preterm among younger women. Neighborhood variability (MOR_{null model}=3.93) remained after adjustment for individual and block socioeconomic characteristics (MOR=3.91) and neighborhood social class did not explain the observed variance (vs. low: IOR_intermediate=0.09-15.40; IOR_rich=0.07-12.07). Variability was found for preterm (MOR_{null model}=2.99) but disappeared after adjustment (MOR=1.11) although area-level social conditions did not contribute to explain it (IOR_intermediate=0.91-1.56; IOR_rich=0.88-1.41). No neighborhood variance was found for SGA.

Conclusions: An independent area-level effect on the adequate beginning of prenatal care was found beyond individual characteristics and may be explained by other social processes than neighborhood social class. No such effect appeared on pregnancy outcomes probably because neighborhood deprivation was overcome by universal access to medical care.