The association between prenatal Doppler ultrasound measurements and postnatal tissue oxygenation in intrauterine growth restricted (IUGR) infants.

Background: Intrauterine growth restricted (IUGR) fetuses are at risk of mortality and neonatal morbidity. IUGR often leads to a redistribution of the fetal circulation. Blood flow to the brain is relatively spared, whereas that to the abdominal organs is reduced. It is unknown how the distribution of the circulation changes after birth in IUGR infants. Aim: To determine the relation between the Doppler ultrasound measurements in IUGR fetuses and the distribution of the circulation in IUGR infants up to three days after birth. Methods: Prospectively we included IUGR infants immediately after birth, of whom the mothers were monitored because of suspected IUGR at the Department of Obstetrics and Gynaecology in the UMCG between May 2012 and July 2013. Inclusion criteria were all gestational ages up to of 42 weeks, and the fetuses having an abdominal circumference below the 10th percentile. We excluded fetuses and children with chromosomal abnormalities, syndromes and congenital infections. From the moment IUGR was diagnosed we performed Doppler ultrasound measurements weekly, and calculated the PI of the fetal umbilical artery, middle cerebral artery and ductus venosus. After birth we performed NIRS measurements during the first 3 days, for two hours continuously on each day. As outcome measures we used multisite NIRS values, i.e. rSO2, transcutaneous SO2 (SpO2), and calculated the fractional tissue oxygen extraction (FTOE) in cerebral, renal and abdominal (splanchnic) tissue. Additonally we calculated the rSO2- and FTOE-ratios between several organs. Then, we calculated correlation coefficients between the PI values of the last fetal measurement before birth and the NIRS values including the ratios after birth, using Spearman’s rank order correlation test. Results: We included 21 infants with a median gestational age of 38 weeks (interquartile range IQR 37-39), a median birth weight of 2195 grams (1925-2535) and a median cerebral circumference of 31 cm (30-32). All infants had a birth weight