Article Text
Abstract
Fetal/Placental weight ratio (FPWR) is a useful tool for assessing fetal growth, which is consistent across ethnic groups (Perry, 1995). The FPWR increases during gestation (Pardi, 2002) but IUGR pregnancies have been shown to be associated with reduced FPWR compared to normal singleton pregnancies of the same gestation (Heinenon, 2001, Pardi 2002, Vedmedovska 2011). However defining IUGR as birthweight <5th centile for gestation will draw in small for gestational age foetuses that may have been small throughout pregnancy but grew at a normal velocity. Therefore we sought to determine if foetuses with IUGR defined by faltering growth on serial ultrasonic measurements of fetal dimensions also show reduced FPWR. We identified 31 singleton placentae, with mean gestation at delivery 37 weeks (standard deviation 2 weeks). 10 placentae from pregnancies with normal fetal growth velocity were used as controls. Using the recorded birthweight and the post-fixation, trimmed placenta weight, FPWRs were calculated and compared to gestational age specific FPWR centile charts for singleton deliveries (Wallace, 2012). The FPWR from the IUGR pregnancies were significantly greater than the controls and reference populations (ANOVA p < 0.0001, R2 0.43). This is in contrast to studies where IUGR was defined as birthweight <5th centile for gestation and raises questions about how the processes causing IUGR change the pattern of fetal and placental growth in utero, if the insult occurs in early pregnancy when the rate of placental weight increase is much faster than that fetal wight thus the placental weight may be more greatly affected than the fetal weight resulting in an increased FPWR.