Reduced fetal growth velocity and weight loss are associated with adverse perinatal outcome in fetuses at risk of growth restriction.

BACKGROUND: Although fetal size is associated with adverse perinatal outcome, the relationship between fetal growth velocity and adverse perinatal outcome is unclear. OBJECTIVE: This study aimed to evaluate the relationship between fetal growth velocity and signs of cerebral blood flow redistribution, and their association with birthweight and adverse perinatal outcome. STUDY DESIGN: This study was a secondary analysis of the TRUFFLE-2 multicenter observational prospective feasibility study of fetuses at risk of fetal growth restriction between 32+0 and 36+6 weeks of gestation (n=856), evaluated by ultrasound biometry and umbilical and middle cerebral artery Doppler. Individual fetal growth velocity was calculated from the difference of birthweight and estimated fetal weight at 3, 2, and 1 week before delivery, and by linear regression of all available estimated fetal weight measurements. Fetal estimated weight and birthweight were expressed as absolute value and as multiple of the median for statistical calculation. The coefficients of the individual linear regression of estimated fetal weight measurements (growth velocity; g/wk) were plotted against the last umbilical-cerebral ratio with subclassification for perinatal outcome. The association of these measurements with adverse perinatal outcome was assessed. The adverse perinatal outcome was a composite of abnormal condition at birth or major neonatal morbidity. RESULTS: Adverse perinatal outcome was more frequent among fetuses whose antenatal growth was <100 g/wk, irrespective of signs of cerebral blood flow redistribution. Infants with birthweight <0.65 multiple of the median were enrolled earlier, had the lowest fetal growth velocity, higher umbilical-cerebral ratio, and were more likely to have adverse perinatal outcome. A decreasing fetal growth velocity was observed in 163 (19%) women in whom the estimated fetal weight multiple of the median regression coefficient was <-0.025, and who had higher umbilical-cerebral ratio values and more frequent adverse perinatal outcome; 67 (41%; 8% of total group) of these women had negative growth velocity. Estimated fetal weight and umbilical-cerebral ratio at admission and fetal growth velocity combined by logistic regression had a higher association with adverse perinatal outcome than any of those parameters separately (relative risk, 3.3; 95% confidence interval, 2.3-4.8). CONCLUSION: In fetuses at risk of late preterm fetal growth restriction, reduced growth velocity is associated with an increased risk of adverse perinatal outcome, irrespective of signs of cerebral blood flow redistribution. Some fetuses showed negative growth velocity, suggesting catabolic metabolism.

Fetal weight change close to term is proportional to the birthweight percentile.

OBJECTIVE: To investigate the relationship between the difference in estimated fetal weight and birthweight at or close to term, and in relation to Doppler parameters. STUDY DESIGN: A cohort study of all term singleton pregnancies who underwent an ultrasound within two weeks of delivery after 36 weeks at one institution in one calendar year. When available, Doppler measurements of umbilical and middle cerebral artery pulsatility index were recorded. Data were analysed by Pearson rank correlation. RESULTS: Of 8517 eligible deliveries, 885 women had an ultrasound scan within 2 weeks of delivery. Mean daily differences between estimated fetal weight and birth weight were: those born <10th percentile lost 26 g per day (95 % CI -36 to -16), 10-50th percentile gained 7 g per day (95 % CI -2 to 15), 50th-90th percentile gained 27 g per day (95 % CI 19-35) and >90th percentile gained 48 g per day (95 % CI 32-64). There was a negative correlation between umbilical: middle cerebral artery pulsatility index and the change in weight per day (n = 348, p = 0.001, r = 0.17). CONCLUSIONS: Difference in the estimated fetal weight and birthweight, expressed as grams growth per day, is proportional to the birthweight percentile. Fetuses with a birthweight >10th percentile gain weight, while those with a birthweight <10th percentile apparently decline in weight between their final ultrasound estimated fetal weight and delivery. In babies with the smallest or apparent negative weight gain there was an association with Doppler parameters that signified hypoxia indicating fetal growth at term may be restricted by impaired placental function. Estimated fetal weight may be a poor predictor of birthweight for reasons other than ultrasound or algorithmic error.