EP08.17: Variations in first trimester fetal growth in pregnancies conceived by assisted reproductive technology

To examine variations in fetal growth in the first trimester among singleton pregnancies conceived by assisted reproductive technology (ART), including both fresh and frozen thawed embryos. In this longitudinal study we included 127 women after single embryo transfer (ET) of a day 5 blastocyst, with one normally sited gestational sac (GS) and a visible yolk sac (YS) confirmed with vaginal ultrasound scan 21 days after ET, corresponding to gestational week (GW) 5+5. The patients had additional ultrasound scans in GW 8+5 and 12+5. Traditional fetal growth trajectories were measured. 14/127 miscarried or withdrew from the study, leaving 113 live pregnancies for final investigation. In GW 5+5, mean diameter of the GS was 10,3mm (95% CI [9.86-10.7], range 5.1-16.1mm), and mean diameter of the YS was 3.3mm (95% CI [3.16-3.34], range 1.7-4.4mm). 115/127 (91%) of the pregnancies had a clearly visible embryo in GW 5+5. The mean CRL was 1.3mm (95% CI [1.28-1.41], range 0.7-2.6mm). In GW 8+5, mean CRL was 20.8mm (95% CI [20.6-21.0], range 17.9-24.7mm). In GW 12+5, mean CRL was 67.7mm (95% CI [67.0-68.3], range 57-75mm), BPD 23.8mm (95% CI [23.6-24.0], range 21-27mm), and FL 8.9mm (95% CI [8.75-9.14], range 6-11mm). 105 (82%) of the included women were pregnant after frozen ET, 22 (18%) after fresh ET. Sub analyses did not reveal any differences in mean CRL between pregnancies after fresh or frozen thawed ET at any of the three examinations. There are variations in fetal growth during the first trimester for pregnancies examined the exact same number of days after ET. We found no differences in fetal growth when comparing pregnancies after ET of fresh or frozen thawed embryos. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.