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PLD.43 Fetal gender imbalance in emergency Caesarean section: The search for an explanation
  1. K James,
  2. S Goodwin,
  3. DG Bogod
  1. Nottingham University Hospitals NHS Trust, Nottingham, UK


The literature consistently suggests that there is an association between fetal sex and need for intervention in labour. Studies suggest that the percentage of singleton Caesarean sections in which parturients deliver a male baby is between 53% and 56%,1,2 with one relatively small series reaching 59%.3 This disparity is too big to be explained by the slightly higher overall birth rate for boys in the UK and elsewhere.

Our analysis of one year’s data at a large tertiary referral unit has revealed a marked male preponderance in women delivered by non-elective Caesarean section (62% boys vs 38% girls). This is a highly significant finding (p < 0.00001), and is considerably greater than any such imbalance previously reported.

This paper will consider the possible factors leading to this disparity, including neonatal weight and head circumference, in an attempt to explain the apparent disparity. Historical data for the same unit will be analysed in order to determine whether any temporal trends exist.


  1. Smith GCS. A population study of birth weight and the risk of caesarean section: Scotland 1980–1996. BJOG 2000;107:740–44

  2. Sheiner E. The relationship between fetal gender and pregnancy outcome. Arch Gynecol Obstet 2007;275:317–319

  3. Eogan MA, Geary MP, O’Connell MP, et al. Effect of fetal sex on labour and delivery: retrospective review. BMJ 2003;326:137

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