Overweight and obese pre-pregnancy BMI is associated with higher hospital costs of childbirth in England

BACKGROUND: Women who have an overweight or obese BMI are more likely to experience pregnancy complications. However, little is known on the cost of childbirth in this group and no studies have been undertaken in England to date. The aim of this paper is therefore to investigate whether women with overweight and obese pre-pregnancy body mass index (BMI) incur higher average hospital costs of childbirth. METHODS: We employed data from 7564 women in the first wave of data collection of the Millennium Cohort Study. Using interval regression, we investigated the association between hospital costs of childbirth and pre-pregnancy BMI, fitting four models, progressively adjusting for additional potential confounders and mediators. Model 1 was a univariate model; model 2 adjusted for maternal age, education, marital status, ethnicity, income, and region; model 3 additionally included number of previous children, number of babies delivered, whether birth was at term, and type of delivery; model 4 also included length of hospital stay. RESULTS: Childbirth costs incurred by women who were overweight, obese class I and obese class II and III were £22, £82 and £126 higher than those incurred by women whose BMI was in the normal range (p ≤ 0.05). Delivery method, pre-term delivery, and length of hospital stay accounted for the observed difference. CONCLUSIONS: Women with elevated pre-pregnancy BMI make greater use of services resulting in higher hospital costs. Interventions promoting healthy BMI in pre-pregnancy among women of child-bearing age have the potential to reduce pregnancy complications and be cost-effective. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12884-018-1893-z) contains supplementary material, which is available to authorized users.