Daijiworld Media Network - Beijing

Beijing, Feb 10: Frozen embryo transfer has been found to be associated with a higher risk of pregnancy-induced hypertension compared to fresh embryo transfer, even though both methods show similar perinatal complication rates in ongoing pregnancies conceived through assisted reproductive technologies, according to a recent study.

The findings are based on a prospective cohort study conducted within a hypothetical randomised controlled trial framework. Researchers analysed data from 2,856 pregnant women recruited during the first trimester from 50 centres across 17 provinces in China between 2017 and 2021. All participants conceived through in vitro fertilisation (IVF) or intracytoplasmic sperm injection (ICSI) and were equally assigned to either frozen embryo transfer or fresh embryo transfer groups.

The primary outcome assessed was the rate of perinatal complications, defined as perinatal death or birth defects. Results showed comparable rates between the two groups, with 5.0 per cent in the frozen embryo transfer group and 4.6 per cent in the fresh embryo transfer group. Researchers noted that the difference was not statistically significant.

Secondary neonatal outcomes, including preterm birth, small or large size for gestational age, low birth weight and macrosomia, were also similar across both groups, indicating comparable neonatal safety profiles for frozen and fresh embryo transfer in ongoing IVF and ICSI pregnancies.

However, the study highlighted a notable difference in maternal outcomes. Women who underwent frozen embryo transfer faced a significantly higher risk of developing pregnancy-induced hypertension compared to those who received fresh embryo transfer. No significant differences were observed between the two groups in terms of abortion rates, gestational diabetes mellitus or gestational thyroid dysfunction.

Researchers said the findings underline the need for careful and individualised counselling when choosing an embryo transfer strategy in assisted reproductive treatment. While neonatal outcomes appear largely similar, the increased maternal risk associated with frozen embryo transfer should be factored into clinical decision-making, they added.