Maternal vascular indices at 36 weeks' gestation in pregnancy with small or growth-restricted fetus.

Objective: To compare maternal vascular indices and hemodynamic parameters at 35-37 weeks' gestation in pregnancies complicated by delivery of a small-for-gestational-age (SGA) or growth-restricted (FGR) neonate.

Methods: This was a prospective observational study of women with a singleton pregnancy attending for a routine hospital visit at 35 + 0 to 36 + 6 weeks' gestation. The visit included recording of maternal demographic characteristics, medical history, vascular indices and hemodynamic parameters, which were obtained using a non-invasive operator-independent device and included pulse-wave velocity, augmentation index, cardiac output, stroke volume, central systolic and diastolic blood pressure, total peripheral resistance and heart rate. Women with hypertensive disorders of pregnancy were excluded. SGA was diagnosed if birth weight was < 10^th percentile. FGR was diagnosed if, in addition to birth weight < 10^th percentile, at the 35-37-week scan, uterine artery or umbilical artery pulsatility index (PI) was > 95^th percentile or fetal middle cerebral artery PI was < 5^th percentile.

Results: Among the 6413 women included in the study, there were 605 (9.4%) cases of SGA, 133 (2.1%) cases of FGR and 5675 (88.5%) cases that were 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 increased in the FGR group compared with the unaffected group. Aortic stiffness, as assessed by pulse-wave velocity, and augmentation index did not differ between affected and unaffected pregnancies. In the FGR group, compared with the SGA group, central systolic and diastolic blood pressure were higher, whereas heart rate was lower.

Conclusions: SGA and FGR pregnancies exhibit deranged maternal hemodynamic responses compared with unaffected pregnancies. Pregnancies with FGR have higher central blood pressure compared to those with SGA, but it remains unclear whether these differences are driven by the size of the fetus or pathological fetal growth. © 2024 International Society of Ultrasound in Obstetrics and Gynecology.