OP20.09: Differences in fetal fat distribution in the presence of abnormal umbilical artery Doppler waveforms

Abstract

(FGR). Methods: During routine assessment of pregnancies known to be at high risk where there were abnormal umbilical artery Doppler waveforms the amounts of fetal abdominal and mid-thigh fat were calculated (fetal subcutaneous fat layer = total area–lean mass area). These were compared with normative data that were collected as part of a continuing ongoing long-term study of fetal growth parameters in a non-smoking cohort of women with uncomplicated pregnancies. Results: Fifty-two pregancies were studied from 24 weeks’ to 39 weeks’ gestation where the umbilical artery S/D was greater than the 95 th centile for gestation. While there was overall an increase in the numbers of fetuses with abdominal and mid-thigh measurements less than the 50 th centile this was only significant for the abdominal measurements, with 87% being less than the 50 th centile for total abdominal area and abdominal lean mass and 92% being less than the 50 th centile for abdominal fat area (Chi square 36.6, P = 0.000). The main component of the decrease in abdominal area was in the subcutaneous fat layer (with 33% being less than the 5 th centile for gestation). The effect was not as clear for the mid-thigh reduction in measurements (with 62% being < 50th centile) but the main component for the mid-thigh was a reduction in fetal thigh subcutaneous fat (13% < 5th centile). Conclusions: There is a difference in the fetal response to FGR (as indicated by abnormal umbilical artery S/D) between the maintenance of both lean body mass and subcutaneous fat. There appears to be a prefence for the preservation of lean body mass and subcutaneous fat peripherally in comparison, with a more global reduction centrally.