Dynamic growth changes in fetal growth restriction using serial ultrasonographic biometry and umbilical artery doppler: the multicenter PORTO study

Objective: To describe the growth dynamics of fetuses with initial fetal growth restriction (FGR) later outgrowing the 10th centile for estimated fetal weight with respect to perinatal outcomes and maternal factors.

Methods: A multicenter prospective study recruited 1116 patients for ultrasound surveillance between 2010 and 2012. All pregnancies were growth-restricted singleton gestations between 24 + 0 and 36 + 0 weeks. Biometry and Doppler analysis were carried out, and delivery and adverse perinatal outcomes were recorded.

Results: A total of 193 (17%) fetuses outgrew their diagnosis of initial FGR (surpassed the 10th centile) on their last sonogram before delivery. These fetuses were termed "growers," to compare with the true FGR group. The mothers of "growers" were less likely to be smokers (14% vs 25%, P = 0.0001) or affected by hypertensive pregnancy complications (5.2% vs 15%, P = 0.001). Of the growers, 49 (25%) had an abnormal umbilical artery Doppler; however, in most cases (33/49, 67%), this was a single episode of raised umbilical artery pulsatility index, which subsequently normalized.

Conclusion: There were dynamic growth changes in FGR fetuses, with 17% outgrowing their original diagnosis. Positive growth spurts more commonly occurred in healthy mothers. Once a fetus had outgrown the 10th centile, antenatal surveillance could be decreased.