EP17.73: Prediction of preterm birth and low birthweight from the first trimester combined test in euploid fetuses

To evaluate if it is possible to predict preterm birth (PTB) between 28-34 weeks and low birthweight (LBW)< 5th centile in euploid fetuses that are screened using the first trimester combined test. This is a retrospective study on singleton pregnancies from a tertiary fetal care centre in South India from 2015-2023. All singleton pregnancies with first trimester combined screening (NT scan+ß hCG, PAPPA, PLGF and AFP) between 11-13+6 weeks by FMF certified operators were included. Data was stored in Astraia software. The outcomes of pregnancies were obtained by telephonic interview of parents and review of delivery details. Pregnancies with structural defects in first trimester scan and proven genetically abnormal fetuses were excluded. Pregnancies were categorised as high, intermediate and low risk when adjusted risk for Trisomy 21 was >1 in 250, 251-999 and <1000. 1382/1395 combined first trimester screens, were analysed after exclusion of fetuses with structural and chromosomal anomalies. 31 (2.2%), 44 (3.2%) and 1313 (95%) were categorised in the high, intermediate and low risk respectively. 63 (4.6%) had PTB between 28-34 weeks and 116 (8.4%) had a BW< 5th centile. 2/31 (6.5%) in the high-risk group had PTB between 28-34 weeks, 3/31 (9.7%) had BW<5th centile and 23 (74.2%) had livebirths. 3/44 (6.8%) in the intermediate group had PTB between 28-34 weeks, 5/44 (11.4%) had BW<5th centile and 37 (84.1%) had livebirths. 59/1313 (4.5%) in the low-risk group had preterm births between 28-34 weeks,108/1313 (8.2%) had BW<5th centile and 1264/1313 (96.3%) had livebirths. On comparison using chi squared tests, these results were not statistically significant as the p value was 0.05 for all. In our study, we did not find a significant association for prediction for PTB between 28-34 weeks and BW < 5th centile by aneuploidy screening using the combined test. However, there were relatively more live births in the low and the intermediate risk groups. We recommend further screening modalities to improve the prediction of preterm delivery and low birthweight.