Introduction: Obesity is associated with a two fold increase in stillbirth with rates exponentially rising after 39/40. In 2009, Australia’s stillbirth rate was 7.8/1000 births, with obesity the highest contributing risk factor. With the increasing prevalence of obesity, with 50% of Australia’s reproductive population being overweight or obese and NHMRC predicting a further 65% increase by 2025, literature is wanting as to whether early induction in obese women reduces perinatal mortality.
Methods: Retrospective cohort study comparing perinatal mortality in pregnant women with BMI>35 2 years prior to and 2 years post the implementation of a policy in 2011 to induce prior to 41/40; at a secondary Sydney hospital. Data was collected from electronic records. Primary outcomes included rates of perinatal mortality, 5 minute Apgar <7, cord arterial pH<7.1 and special care nursery admission >48hrs. Secondary outcomes included rates of macrosomia, shoulder dystocia, instrumentals and emergency caesarean sections.
Results: 1368 women met the selection criteria (569 pre-policy vs 799 post-policy). Induction in women with BMI>35 at <41/40 increased (35.7% to 43.3%, P=0.074) with a decrease in women delivering >41/40 (12.3% to 6.63%, P=0.0003). Perinatal mortality reduced (0.35% to 0.1%, P=0.57), however, Apgar<7, cord pH<7.1 and SCN admissions increased (1.58% to 3.75%, P=0.02; 0% to 0.25%, P=0.51; 7.2% to 7.26%, P=0.97 respectively). Rates of instrumentals and macrosomia reduced (4.22% to 3.88%, P=0.75; 4.39% to 3.5%, P=0.4 respectively), although rates of shoulder dystocia increased (0.88% to 1.1%, P=0.65). Rates of emergency caesarean sections increased (8.62% to 8.95%, P=0.84).
Conclusion: Whilst there were no statistically significant findings in relation to primary and secondary outcomes, trends in data reveal that early induction in obese women reduces perinatal mortality, macrosomia and instrumental delivery rates. However data trends also reveal that early induction increases perinatal morbidity as well as emergency caesarean section rates. Further research with a larger cohort is thus required to clarify these associations prior to recommending this induction policy as best practice.