Impaired placental perfusion and major fetal cardiac defects

To investigate the relationship between fetal congenital heart defects (CHD) and placental perfusion assessed by uterine artery pulsatility index (UtA-PI), in relation to development of pre-eclampsia (PE).

This was a prospective screening study of singleton pregnancies at 19-24 weeks' gestation. Transvaginal ultrasound was used to measure UtA-PI and the values were converted into multiples of the normal median (MoM). Median MoM values in pregnancies with a fetus with isolated major CHD were compared to those without CHD, in relation to development of PE.

The 91 407 singleton pregnancies fulfilling the entry criteria included 206 (0.23%) with isolated major fetal CHD and 91 201 without CHD. The prevalence of PE was 4.4% in pregnancies with fetal CHD and 2.7% in those without CHD (relative risk (RR), 1.6 (95% CI, 0.84-3.04); P = 0.150); the respective values for preterm PE with delivery at < 37 weeks' gestation were 2.4% and 0.7% (RR, 3.4 (95% CI, 1.42-8.09); P = 0.006). In the total population, median UtA-PI MoM was significantly higher in those that developed PE compared to those without PE (1.22 (interquartile range (IQR), 0.94-1.57) vs 1.00 (IQR, 0.84-1.19); P < 0.0001) and, in the PE group, the median UtA-PI MoM was inversely related to gestational age at delivery (r = -0.458; P < 0.0001). The same pattern of inverse relationship between UtA-PI MoM and gestational age at delivery with PE was observed in pregnancies with and those without CHD, but, in the CHD group, compared to those without CHD, UtA-PI was significantly higher both in pregnancies with and in those without PE.

In pregnancies both with and without fetal CHD that develop PE, impedance to flow in the UtAs is increased and this increase is particularly marked in those with preterm PE. The prevalence of preterm PE is more than three times higher in pregnancies with than those without fetal major CHD, and the prevalence of major CHD in pregnancies with preterm PE is also more than three times higher than in those without PE. However, > 97% of pregnancies with fetal CHD do not develop preterm PE and > 99% of pregnancies with preterm PE are not associated with fetal CHD. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.