Trends and patterns of low birth weight and fetal macrosomia in a tertiary hospital, Northern Ethiopia, 2012–2021: multinomial modeling approach

Abstract

Low birth weight (LBW) and fetal macrosomia represent critical extremes of the birth weight spectrum, posing substantial public health challenges in low- and middle-income countries. Although traditionally studied in isolation, these outcomes share underlying systemic factors that warrant simultaneous evaluation. Evidence examining their joint distribution, temporal trends, and shared determinants within the same population remains sparse. To address this gap, this study investigated the in-hospital prevalence, trends, and associated factors of both conditions using a multinomial modeling approach at a tertiary hospital in Northern Ethiopia. A hospital-based cross-sectional study was conducted using delivery register data from Ayder Comprehensive Specialized Hospital, encompassing 24,709 live births with complete birth weight records between January 2012 and August 2021. Temporal trends were visualized using line graphs, while a multinomial logistic regression model was employed to identify associated factors of LBW and fetal macrosomia, with results reported as Relative Risk Ratios (RRR) and corresponding 95% Confidence Intervals (CI). The in-hospital prevalence was 12.55% (95% CI: 12.14%–12.97%) for LBW and 6.82% (95% CI: 6.51%–7.14%) for fetal macrosomia. LBW was significantly associated with female infant sex (RRR = 1.16; 95% CI: 1.06–1.27), instrumental delivery (RRR = 0.80; 95% CI: 0.69–0.92), obstetric complications (RRR = 2.90; 95% CI: 2.49–3.37), higher parity (RRR = 13.27; 95% CI: 11.51–15.29), and low APGAR scores (RRR = 4.54; 95% CI: 3.89–5.31). Conversely, fetal macrosomia was linked to high-risk maternal age (RRR = 1.34; 95% CI: 1.12–1.61), female infant sex (RRR = 0.64; 95% CI: 0.57–0.72), spontaneous vaginal delivery (RRR = 0.47; 95% CI: 0.42–0.52), instrumental delivery (RRR = 0.23; 95% CI: 0.19–0.28), higher parity (RRR = 0.04; 95% CI: 0.01–0.17), low APGAR scores (RRR = 0.63; 95% CI: 0.44–0.91), and maternal HIV positivity (RRR = 0.40; 95% CI: 0.25–0.64). The study demonstrates a notable burden of both LBW and fetal macrosomia over the decade. These findings emphasize the necessity for targeted clinical interventions, enhanced intrapartum monitoring, and specialized care for high-risk cohorts—such as mothers with obstetric complications and HIV-positive women—to mitigate adverse birth outcomes.