Impact of suspected late-onset fetal growth restriction on obstetrical interventions and perinatal outcomes at term; a retrospective cohort study.

Objectives: First, assess accuracy of late third trimester universal fetal growth screening in high risk nulliparous women with a singleton in vertex presentation at term. Second, assess instrumental delivery rates and perinatal outcomes in this population.

Study Design: Single centre retrospective cohort study in a teaching hospital, The Netherlands.

Results: In a cohort of 1902 pregnancies, growth ultrasound after 33 weeks was moderately accurate in detecting children with a birthweight below the 10th centile with a sensitivity of 46.2% and a false positive rate of 4.7%. Induction of labour followed an antenatal suspicion of FGR more often than in the group with normal expected fetal weight (73.4% vs 52.6% OR 2.49 (1.88-3.3)) as could be expected from application of guidelines. The caesarean section rates was lowest in the group with suspected FGR compared to the group with expected normal fetal weight (15.2% vs 22.1% OR 0.63 (0.45-0.9)). There were no differences between both groups in rates of composite severe adverse perinatal outcome (0.7% vs 0.8% OR 0.87 (0.2-3.93)).

Conclusions: The detection of growth restriction using universal screening in term high risk nulliparous women with a singleton in vertex position is moderate. Despite this, caesarean section rates were not increased and perinatal outcomes were similar when compared to that found in the randomized controlled trial on which the recommendation for induction of labour for suspected term FGR is based. This supports universal late third trimester fetal growth screening in pregnancies under consultant-led care in the two tiers Dutch obstetrical system.