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Maternal Medicine Posters
How does bmi affect delivery and neonatal outcomes?
  1. S Mittal,
  2. M MacDougall
  1. Royal Victoria Infirmary, Newcastle, United Kingdom


Background National guidance has suggested increased surveillance in patients with a raised BMI which has placed a massive burden on resources.

Methods We looked at 10614 consecutive deliveries prior to the changes in surveillance to describe BMI's association with; mode of delivery, birth weight less than 2.5kg, birth weight over 4.0kg, postpartum haemorrhage, arterial cord pH<7.1, arterial cord pH<7.0, admission to S.C.B.U., and stillbirth.

Results Compared to those with a BMI between 18.5-25, those with a BMI over 40 were significantly (p<0.001) more likely to deliver by emergency caesarean section (20.15% [54/268] v 12.39% [683/5512]) RR 1.626 or elective caesarean section (19.4% [52/268] v 9.8% [541/5512]) RR 1.977, and significantly less likely (p<0.01) to have a spontaneous vaginal delivery 52.61% [141/268] v 60.7% [3346/5512]) RR 0.866 or assisted vaginal delivery (7.46% [20/268] v 16.56% [913/5512]) RR 0.4505. Although they appeared to have fewer babies below 2.5kg (5.59% [15/268] v 9.14% [504/5512], this was not statistically significant (p=0.06). They were significantly more likely (p<0.0001) to have a baby over 4.0kg (20.9% [56/268] v 8.6% [477/5512]) and significantly more likely to have a postpartum haemorrhage (30.9% [83/268] v 19.6% [1082/5512]).

In terms of neonatal outcomes admission to S.C.B.U. was no more likely (p=0.537) (3.3% [9/268] v 4.3% [239/5512]), arterial cord pH was no more likely to be below 7.1 (p=0.68) (3.4% [190/5512] v 4.1% [11/268]) or below 7.0 (p=0.98)(0.5% [30/5512] v 0.7% [2/268]) and stillbirth rates were no higher (p=0.85)(0.47% [26/5512] v 0.74% [2/268]).

Conclusion In our unit the biggest impact BMI has seems to be on mode of delivery, birth weight and postpartum haemorrhage rates with little impact on neonatal outcome. Our local data suggest that the increase in surveillance suggested nationally may bring little yield.

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