Association between blastocyst morphometrics and live birth, obstetric complications and perinatal outcomes

Research questionAre blastocyst morphometrics, specifically diameter, inner cell mass (ICM) area and trophectoderm (TE) cell count, associated with live birth, obstetric complications and perinatal outcomes? DesignA retrospective single-center cohort study of 1,227 vitrified-warmed single blastocyst transfers performed between May 2018 and July 2024.Blastocyst diameter, ICM area and TE cell count were quantitatively measured prior to vitrification.We evaluated the effects of the blastocyst morphometric parameters on live birth, obstetric complications and perinatal outcomes using statistical models that accounted for potential confounding factors. ResultsEach 100-m 2 increase in the ICM area and each 10-cell increase in TE cell count were associated with increased live birth rates (ICM area: marginal odds ratio [mOR]=1.023,95% CI [1.009, 1037], P=0.001; TE cell count: mOR=1.101,95% CI [1.038, 1.168], P=0.001).Each 10-cell increase in TE cell count was significantly associated with increased birth weight (=19.47g,95% CI [4.91, 34.02], P=0.010) and placental weight (=8.64g,95% CI [3.00, 14.27], P=0.003), as well as with a reduced risk of low birth weight (LBW) (mOR=0.860,95% CI [0.743, 0.995], P=0.044), small for gestational age (SGA) (mOR=0.693,95% CI [0.541, 0.888], P=0.004), and hypertensive disorders of pregnancy (HDP) (mOR=0.740,95% CI [0.600, 0.912], P=0.005). ConclusionsBoth the ICM area and TE cell count were independently associated with live births following embryo transfer.Once pregnancy is established, TE morphology, specifically TE cell count, further influences birth weight, placental weight and incidence of LBW, SGA and HDP.