Maternal vascular indices at 36 weeks' gestation in small and growth restricted fetuses.

ABSTRACT

OBJECTIVE: To compare maternal vascular indices and hemodynamic parameters at 35-37 weeks' gestation, in pregnancies complicated by small for gestational age (SGA) fetuses and those with fetal growth restriction (FGR). METHODS: This was a prospective observational non-intervention study in women with singleton pregnancies attending for a routine hospital visit at 35+0 to 36+6 weeks' gestation. The visit included recording of maternal demographic characteristics and medical history, vascular indices and hemodynamic parameters obtained by a non-invasive operator independent device, including pulse wave velocity, augmention index, cardiac output, stroke volume, central systolic and diastolic blood pressure, total peripheral resistance and fetal heart rate. Hypertensive disorders of pregnancy were excluded and the values in the SGA and FGR groups were compared between them and with unaffected pregnancies. Diagnosis of SGA was based on the birth of a baby with birthweight below the 10th percentile for gestational age. In FGR, in addition to a birthweight below the 10th percentile, at the 35-37 weeks scan Doppler studies had shown that the uterine artery or umbilical artery pulsatility index (PI) was above the 95th percentile for gestational age or the fetal middle cerebral artery PI was below the 5th percentile. RESULTS: In the 6,413 women included in the study there were 605 (9.4%) cases of SGA, 133 (2.1%) of FGR and 5,675 (88.5%) unaffected by SGA or FGR. Women with SGA or FGR, compared to unaffected pregnancies, had increased peripheral vascular resistance and reduced cardiac output. Central systolic and diastolic blood pressure were also increased, whereas aortic stiffness assessed by pulse wave velocity and augmentation index did not differ between affected and unaffected pregnancies. In the FGR, compared to the SGA group, central systolic and diastolic blood pressure were higher, whereas, heart rate was lower. CONCLUSIONS: In SGA and FGR pregnancies there are deranged maternal hemodynamic responses when these are compared to normal pregnancies. Mothers with FGR babies have higher central blood pressure compared to SGA ones, but it remains unclear whether these differences are driven by the size of the fetus or pathological fetal growth. This article is protected by copyright. All rights reserved.