Twinning

Multiple pregnancy is one of the most significant risks associated with fertility treatment. Transferring two embryos at once roughly doubles the risk of twins compared to single embryo transfer (SET). Twin pregnancies carry higher rates of preterm birth, low birth weight, cesarean delivery, NICU admission, and maternal complications.

Medical societies including ASRM now strongly recommend elective single embryo transfer (eSET) in most patients under 38 with good-quality blastocysts, particularly when PGT-A has confirmed euploidy.

With the freeze-all approach and improved cryopreservation, cumulative success rates with eSET across multiple frozen transfers now match or exceed twin-pregnancy outcomes with lower risk.