Maternal overweight and obesity increase the risk of fetal acidosis during labor

Objectiveto investigate whether maternal overweight and obesity increased the risk of fetal acidosis measured in umbilical cord arterial blood after delivery.study designpopulation-based cohort study of 84,785 term (≥37 weeks) infants. logistic regression was used to estimate risks of fetal acidosis in umbilical cord arterial blood. fetal acidosis was defined as ph <7.10 or as ph <1st percentile on a normal reference curve.resultrisks of fetal acidosis increased, regardless of definition, with maternal overweight and obesity severity. compared to normal weight (bmi 18.5–<25), the odds ratios (95% confidence interval) for ph <7.10 were 1.35 (1.23–1.47) for overweight (bmi 25–<30), 1.46 (1.27–1.69) for mild obesity (bmi 30–<35), and 1.75 (1.42–2.15) for severe obesity (bmi ≥35). the association for obesity was attenuated in analyses restricted to non-instrumental vaginal deliveries.conclusionmaternal overweight and obesity increased the risk of fetal acidosis. more complicated deliveries in obese women may partially explain this association.