What is the impact of body mass index on external cephalic version


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Scott-Pillai et al.[1] highlight some of the key risks in pregnancy associated with a raised maternal body mass index (BMI). Although we know that obesity results in increased obstetric problems, including increased complications at caesarean section,[2] one important area to consider are the risks associated with malpresentation, namely breech presentation.

In women with a breech presentation the incidence of caesarean section can be reduced by external cephalic version (ECV),[3] and so we therefore performed a restrospective study over a 1-year period to identify whether being overweight was a barrier to successful ECV. We identified women who attended an ECV clinic and were offered the procedure between 1 October 2010 and 1 October 2011. The ECV clinic at our tertiary hospital is held in the antenatal day unit with cardiotocograph and ultrasound scanning facilities after subcutaneous administration of salbutamol for tocolysis. The patients were divided into two groups: group 1 (BMI < 25) and group 2 (BMI ≥ 25).

We found that 66 women attended the ECV clinic with a breech presentation, of whom 18 did not undergo an ECV: 12% of the women of normal weight declined an ECV, whereas only 4% of women who were overweight declined. A total of 48 procedures were performed in 48 women, of whom 30 and 18 were categorised into groups 1 and 2, respectively. There were no statistical differences between groups 1 and 2 in terms of age, parity, or whether an ECV leaflet had been provided. Furthermore, the gestation at the time of the ECV was comparable, as was the seniority of the clinician performing the procedure. The success rate was higher in group 1 at 50%, compared with 33% in group 2 (OR 2.0, 95% CI 0.59–6.73, = 0.26), noting that higher doses of salbutamol were used in group 2 [381 μg (95% CI 369–393) versus 432 μg (95% CI 403–461), P = 0.0006]. None of the women who failed an ECV were offered a repeat procedure. One complication was noted: a case of fetal bradycardia with good recovery in group 1. With respect to the successful ECVs, 60% of group 1 and 50% of group 2 achieved a vaginal delivery (OR 1.5, 95% CI 0.22–10.08, P = 0.68), with comparable lengths of labour (427 versus 406 min, P = 0.93). Overall, the caesarean section rate was 66.7% in group 1 and 86% in group 2 (OR 0.89, 95% CI 0.25–3.27, = 0.87). There were no statistical differences in birthweight or gestation at delivery between the two groups.

It is therefore important that women who are overweight or obese should be appropriately counselled about the success of an ECV, but this should not deter the clinician from attempting the procedure, particularly in a multiparous patient. A higher dose of tocolytic may be required. The routine provision of leaflets may improve uptake of the procedure. Offering a second attempt at ECV may avoid a caesarean section and be particularly pertinent in the obese population.