Estimating the effect of antenatal care models on birthweight in low- and middle-income countries: Evidence from a DHS-based propensity score matching analysis

: Low birthweight (LBW) remains a major public health challenge in low- and middle-income countries (LMICs), accounting for over 95% of the global burden and substantially increasing the risks of neonatal mortality, impaired growth, and adverse lifelong health outcomes. Despite the recognized importance of antenatal care (ANC), robust evidence on the causal effect of different ANC models on birthweight across LMICs remains limited. This study aimed to estimate the effect of adequate ANC utilization on birthweight using propensity score matching (PSM). Method: This study analysed 370,576 women (weighted sample = 369,034) drawn from 52 Demographic and Health Surveys(DHS) conducted across LMICs between 2012 and 2024. Potential confounders associated with both ANC utilization and birthweight were identified using bivariate analyses, including chi-square tests, analysis of variance (ANOVA), and t-tests, and were subsequently incorporated into PSM models. PSM was employed to estimate the effects of receiving at least four ANC visits (ANC4+) and at least eight ANC visits (ANC8+) on birthweight. Both the Average Treatment Effect on the Treated (ATT) and the Average Treatment Effect (ATE) were estimated. Matching quality was assessed using balance diagnostics and graphical evaluations, while Rosenbaum bounds sensitivity analysis was performed to evaluate the robustness of the findings to potential unmeasured confounding. Results: The mean birthweight was 3,034.31 g (SD: 651.65), and the weighted prevalence of LBW was 12.42% (95% CI: 12.31, 12.52). Overall, 69.95% and 20.73% of women received at least four (ANC4+) and eight (ANC8+) ANC visits, respectively. PSM revealed that women who received ANC4+ and ANC8+ delivered newborns weighing, on average, 76.41 g and 104.16 g more than matched controls, respectively (ATT). At the population level, ANC4+ and ANC8+ were associated with average birthweight gains of 60.18 g and 84.61 g, respectively (ATE). Matching diagnostics demonstrated substantial reductions in covariate imbalance and strong post-matching comparability between treatment and control groups, supporting the robustness of the estimated treatment effects. Conclusion: Low birthweight remains a substantial public health burden in LMICs. Adequate ANC was associated with significant improvements in birthweight, with the WHO-recommended ANC8+ model demonstrating greater benefits than ANC4+, indicating a dose-dependent relationship between ANC utilization and fetal growth. Expanding access to and continuity of high-quality ANC services, particularly the ANC8+ contact model, may represent an effective strategy for improving birth outcomes and reducing the burden of LBW across the region.