Effect of fetal growth restriction on ultrasonographically measured cardiac size

The effect of fetal growth restriction on cardiac size is controversial. It has not been established whether cardiac size of small for gestational age (SGA) fetuses is smaller or larger than appropriate for gestational age (AGA) fetuses. Such controversy may stem from heterogeneity in study population in previous reports. Both fetal hypoxemia and increased impedance to flow in fetoplacental vessels, two findings often encountered in severe fetal growth restriction, may lead to cardiomegaly. Therefore we have measured cardiac dimensions and cardiothoracic indices in a homogeneous group of SGA fetuses without ultrasonographic or Doppler evidence of fetal distress or increased umbilical artery flow impedance (n = 10). This group was compared with AGA fetuses matched for sex and estimated fetal weight (n = 20). No differences were observed between the two groups in cardiac and chest measurements and indices. Heart circumference and area significantly correlated with fetal weight, both among AGA (r = 0.88 for both; P < 0.0001), as well as SGA fetuses (r = 0.89 and 0.88, respectively; P = 0.0006 and 0.0008).