Decreased fetal movements—the utility of ultrasound to identify infants at risk and prevent stillbirth is poor

Abstract

Despite a paucity of evidence, it is widely accepted that a perceived reduction in fetal movements is associated with an increased risk of stillbirth and poor obstetrical outcome. Consequently, many international guidelines recommend urgent ultrasound assessment of fetal well-being in women presenting with decreased fetal movements. This study aimed to compare rates of abnormal ultrasound findings reflective of fetal compromise between women presenting with decreased fetal movements and gestation-matched controls in the third trimester. This was a retrospective cohort study performed at the Mater Mothers' Hospital in Brisbane between 2017 and 2020. We undertook propensity score matching analysis comparing abnormal ultrasound parameters in women with singleton, nonanomalous pregnancies presenting with decreased fetal movements after 28 weeks' gestation. The primary outcome was a composite of any abnormal scan parameter: umbilical artery pulsatility index >95th centile, middle cerebral artery pulsatility index <5th centile, cerebroplacental ratio <10th centile, estimated fetal weight <10th centile for gestation, middle cerebral artery peak systolic velocity >1.5 multiples of the median, or deepest vertical pocket of amniotic fluid <2 or >8 cm. After propensity score matching, the study cohort comprised 1466 cases and 2207 controls. The rate of the primary composite outcome was not significantly different between the 2 cohorts (20.2% vs 21.3%; P=.42). There were 30 new cases of small-for-gestational-age detected in the decreased fetal movements cohort, giving a number needed to scan of 48 in the decreased fetal movements group to detect 1 case of small-for-gestational-age. However, the frequency of the composite outcome was higher (13.0% vs 5.4%) at the final scan before birth in women with multiple decreased fetal movement presentations. Despite this, there was no significant difference in clinical outcomes between the 2 cohorts. Ultrasound abnormalities are not increased in women with decreased fetal movements compared with controls.