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Delivery in women with BMI over 55 (query bank)

Published: 26/10/2011


In a pregnant woman with BMI of over 55 is it safer to recommend vaginal delivery or caesarean section?


The CMACE/RCOG Joint Guideline on “Management Of Women With Obesity In Pregnancy” says that:

“Caesarean section can be more technically difficult in [overweight and obese] women and there is a higher risk of anaesthetic complications compared to healthy-weight women. The decision for mode of delivery should therefore be taken only after careful consideration of the individual circumstances and in conjunction with the full multidisciplinary team and the woman herself.

(Evidence level IV)

A national cohort study including 591 extremely obese women delivering in the UK (Homer) (BMI greater than or equal to 50) found no significant differences in anaesthetic, postnatal or neonatal complications between women with planned vaginal delivery and planned caesarean delivery, with the exception of shoulder dystocia (3% versus 0%, P = 0.019). There were no significant differences in any outcomes in the subgroup of women who had no identified medical or antenatal complications.

(Evidence level III)

An updated NICE guideline on caesarean section (National Collaborating Centre for Women's and Children's Health) is due for publication in November 2011. A pre-publication version of this guideline includes the study by Homer and comments that:

“The GDG noted that the evidence from the one UK study involving extremely obese women suggested that outcomes were similar for women planning a vaginal birth and those planning a CS. They felt this was contrary to what many obstetricians currently believe to be the case and that it was important to make a recommendation to underline this finding.

Recommendation: Do not use a body mass index (BMI) of over 50 alone as an indication for planned CS.”

However, this recommendation may change in the final published version of the guideline.

(Evidence level IV)


  • CMACE/RCOG Joint Guideline. Management Of Women With Obesity In Pregnancy. 2010.
  • Homer CS, Kurinczuk JJ, Spark P, Brocklehurst P, Knight M. Planned vaginal delivery or planned caesarean delivery in women with extreme obesity. BJOG. 2011 Mar;118(4):480-7. Abstract. Full text available to Fellows and Members of the RCOG here
  • National Collaborating Centre for Women's and Children's Health. Commissioned by the National Institute for Health and Clinical Excellence. Caesarean section. Clinical guideline 2011.

Search date

October 2011

Classification of evidence levels

  • Ia: Evidence obtained from meta-analysis of randomised controlled trials.
  • Ib: Evidence obtained from at least one randomised controlled trial.
  • IIa: Evidence obtained from at least one well-designed controlled study without randomisation.
  • IIb: Evidence obtained from at least one other type of well-designed quasi-experimental study.
  • III: Evidence obtained from well-designed non-experimental descriptive studies, such as comparative studies, correlation studies and case studies.
  • IV: Evidence obtained from expert committee reports or opinions and/or clinical experience of respected authorities.


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