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Class II and class III maternal obesity and pregnancy-related outcomes: a UK national study
  1. KJ Fitzsimons1,
  2. J Modder1,2
  1. 1Centre for Maternal and Child Enquiries, London, UK
  2. 2University College London (UCL) Institute of Women's Health, London, UK


Maternal obesity is now considered one of the most commonly occurring risk factors in obstetric practice. A UK-wide observational study was conducted to determine the prevalence of class II and class III maternal obesity and to assess the pregnancy-related outcomes in this high-risk group of women. Every maternity unit in the UK was requested to report each woman with a pregnancy body mass index (BMI) ≥35 kg/m2 who gave birth during March and April 2009. Data relating to demographics, co-morbidities, anthropometric measures and pregnancy-related outcomes were collected. A total of 4751 women who had a calculated BMI ≥35 at any point during pregnancy were reported to have given birth during a 7-week period. The mean first-recorded antenatal weight was 104.9 kg and BMI 41.3 kg/m2. The majority (97.8%) of women gave birth in obstetric units, while 1.2% delivered in alongside-midwifery units, 0.3% in free-standing midwifery units and 0.6% at home. 46% of women had a spontaneous onset of labour, 33% were induced and 21% never laboured. Of the 4669 singleton deliveries, 55% were spontaneous vaginal births, 38% were Caesarean sections, 8% instrumental vaginal births and 0.2% vaginal breech births. Eight per cent of women undergoing Caesarean sections required general anaesthesia. Of the singleton babies, 1.3% had a confirmed congenital anomaly, 1% were stillborn and 0.2% had early neonatal deaths. Eight per cent of live born babies were admitted to the neonatal unit within 48 h of birth. Maternal obesity is associated with an increased risk of pregnancy-related complications and adverse outcomes.

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