Mid-trimester estimated fetal weight centile predicts later adverse perinatal outcomes, including at term

To assess whether routinely collected mid-trimester estimated fetal weight (EFW) centile can identify pregnancies at increased risk of poor outcomes due to placental dysfunction, including stillbirth. Hadlock-4 EFW centiles were calculated according to exact gestational age from 15,268 scans performed at 18+0-22+6 weeks inclusive. These were linked with pregnancy outcome data. Logistic regression tested the associations between mid-trimester EFW centile and outcomes of interest: 1. Stillbirth 2. Composite poor outcome - ANY of: perinatal mortality, 5min Apgar < 7, birthweight < 3rd centile, neonatal unit admission for > 48 hr, neonatal unit admission with respiratory support Mid-trimester EFW centile was significantly associated with poor perinatal outcome: 1. Each centile reduction in mid-trimester EFW increased the odds of stillbirth by 2% [95% confidence interval: 1%-3%], p = 0.005; 2. Each centile reduction in mid-trimester EFW increased the odds of the composite of poor outcomes by 1.1% [1.0%-1.4%], p < 0.001. Significantly, even when analysis was limited to babies born at term (removing poor outcomes due to prematurity) and where EFW was > 10th centile at the mid-trimester scan (considered normally grown), EFW centile was still strongly associated with poor outcomes occurring > 15 weeks later. In this specific cohort, each centile reduction in mid-trimester EFW increased the odds of the composite of poor outcomes by 1.2% [0.9%-1.4%], p < 0.001. The lowest rate of poor outcomes occurred among those with a mid-trimester EFW of 90-95th centile. There were exponential increases in poor outcome with falling mid-trimester centile, with significantly increased risk at all centiles below the 50th. Mid-trimester EFW centile is available from data already routinely collected. It is associated with later risks of stillbirth and other poor outcomes related to placental dysfunction. Mid-trimester EFW centile could inform stillbirth risk and fetal surveillance in later pregnancy.