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Influence of birth weight on fetal cardiac indices at 35–37 weeks' gestation
Author(s) -
Semmler J.,
AbdelAzim S.,
Anzoategui S.,
Zhang H.,
Nicolaides K. H.,
Charakida M.
Publication year - 2021
Publication title -
ultrasound in obstetrics and gynecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.202
H-Index - 141
eISSN - 1469-0705
pISSN - 0960-7692
DOI - 10.1002/uog.23522
Subject(s) - medicine , fetus , birth weight , gestational age , gestation , obstetrics , umbilical artery , pregnancy , population , cardiac function curve , ductus venosus , intrauterine growth restriction , fetal echocardiography , cardiology , prenatal diagnosis , heart failure , genetics , environmental health , biology
Objective Echocardiographic studies have reported that fetuses with low birth weight, compared to those with normal birth weight, have globular hearts and reduced cardiac function. Dichotomizing continuous variables, such as birth weight, may be helpful in describing pathology in small studies but can prevent us from identifying physiological responses in relation to change in size. The aim of this study was to explore associations between fetal cardiac morphology and function and birth weight, as a continuous variable, as well as uterine artery (UtA) pulsatility index (PI), as an indirect measure of placental perfusion, and the cerebroplacental ratio (CPR), as an indirect measure of fetal oxygenation. Methods This was a prospective study of 1498 women with singleton pregnancy undergoing routine ultrasound examination at 35 + 0 to 36 + 6 weeks' gestation. Pregnancies complicated by pregestational or gestational diabetes mellitus, chronic hypertension, pregnancy‐induced hypertension or pre‐eclampsia were excluded from the analysis. Conventional and more advanced echocardiographic modalities, such as speckle tracking, were used to assess fetal cardiac function in the right and left ventricles. The morphology of the fetal heart was assessed by calculating the right and left sphericity indices. In addition, the PI of the UtA, umbilical artery (UA) and fetal middle cerebral artery (MCA) was determined and the CPR was calculated by dividing MCA‐PI by UA‐PI. Multiple linear regression models were used to assess determinants of fetal echocardiographic parameters. Results The study population included 146 (9.7%) small‐for‐gestational‐age (SGA) fetuses with birth weight < 10 th percentile and 68 (4.5%) with fetal growth restriction (FGR). In the SGA and FGR groups, compared to the non‐SGA and non‐FGR fetuses, respectively, there was a more globular right ventricle and reduced left and right ventricular systolic function, and, from the left ventricular diastolic functional indices, the E/A ratio was increased. There was a linear association of right ventricular sphericity index, indices of left and right ventricular systolic function and E/A ratio with birth‐weight Z ‐score. There were no significant associations between cardiac morphological and functional indices and UtA‐PI Z ‐score or CPR Z ‐score. Conclusions This screening study at 35–37 weeks' gestation has demonstrated that birth weight is a determinant of fetal cardiac morphologyand function but UtA‐PI and CPR, as indirect measures of placental perfusion and fetal oxygenation, are not. This suggests that the differences in fetal cardiac indices between small and appropriately grown fetuses may be part of a normal physiological response to change in fetal size rather than part of a pathological adaptation to abnormal placental perfusion and fetal oxygenation. © 2020 International Society of Ultrasound in Obstetrics and Gynecology