Objective To determine the effects of Obesity in pregnancy on healthcare costs to the NHS.

Setting Tertiary NHS Foundation Trust in South East London.

Methods Data collection was obtained for all deliveries after 24 weeks from January 2004 to December 2008. Booking BMI was classified according to WHO criteria. Data collected included BMI at booking, gestation at delivery, mode of delivery, duration of stay for delivery and Neonatal admission to NICU or SCBU. Annual cost from increased caesareans, inpatient stay (days) and admissions to NICU/SCBU due to Obesity was estimated using the results for the data analysed.

Results BMI was obtainable for 22,840 deliveries (75%), prevalence of Obesity 14.6%. Caesarean rates increased with Obese BMI: Class I 33.7%, Class II 37.4% and Obese Class III 42% compared to normal BMI (24.1%) At univariate analysis the BMI was associated with longer inpatient stay (days): normal BMI 2.7 (SD 3.5), Obese I mothers 3.4 (SD 4.9), Obese II stayed for 3.9 (SD 5.4) and Obese III 4.0 (SD 4.7) Neonatal admission rates increased with Obesity: Class I 8.3%, Class II 9.7% and Class III 12.3% compared to normal BMI 5.7% When additional numbers of caesareans, inpatient days and admission to SCBU/NICU were equated to national numbers of deliveries in the UK, the estimated cost to the NHS was over £71,000,000 per annum.

Conclusions This evidence suggests the need to address obesity in reproductive women to improve their health as well as their child's and also reduce financial burden on the NHS.