The influence of booking body mass index

Published Date: 26th October 2016

Publication Authors: Anwar A, Yoxall PF

​Introduction

Obesity is a major public health concern with over half of childbearing aged women overweight or obese in the UK. Maternal obesity carries numerous maternal and fetal complications during pregnancy and is a risk factor for anaesthesia related mortality. The incidence of complications such as caesarean section (CS), preeclampsia, induction of labour (IOL) and stillbirth is increased in women with a higher body mass index (BMI). Compared to spontaneous labour, women undergoing IOL are at increased risk of CS. This audit examines the association of booking BMI on the method of delivery, requirement of anaesthetic intervention and risk of general anaesthetic in women undergoing IOL. 

Methods

This is a retrospective study based on 298 women who underwent IOL over a three -month period. Data were collected from the Medway Maternity System and anaesthetic charts. Patients were categorised according to their booking BMI. Modes of delivery and anaesthetic outcomes were compared and data were subjected to logistic regression analysis using the R statistical software package. The likelihood ratio (LR) was calculated with 95% confidence intervals (CI). 

Results

The likelihood of women needing anaesthetic intervention was 0.99-1.06 indicating increasing BMI alone was not a risk factor for anaesthetic intervention during IOL. We found that BMI did not increase the probability of CS with a likelihood ratio of 1.00-1.08. Those women undergoing CS following a failed IOL were not at greater risk of having general compared to a regional anaesthesia. (Figure Presented) 

Discussion

The most common indication for CS is failure to progress following IOL. Studies show CS are strongly related to a low admission Bishop score. Although BMI is known to be an independent risk factor for CS; this was not evident in the women undergoing IOL in this study. This suggests other factors, such as a low Bishop score, may play a more important role leading to CS, the need for anaesthetic intervention and general anaesthetic in comparison to an increased BMI. 

Anwar, A; Yoxall, P. (2016). The influence of booking body mass index on method of delivery, anaesthetic intervention and risk of general anaesthetic in women undergoing induction of labour . International Journal of Obstetric Anesthesia. 26 (Suppl 1), S32

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