# Effect of maternal age, embryo number and quality on pregnancy outcome during frozen embryo transfer cycle

## TL;DR

This study examines how maternal age, number of embryos transferred, and embryo quality affect pregnancy outcomes in frozen embryo transfers.

## Contribution

The study identifies specific correlations between maternal age, embryo quantity and quality, and clinical outcomes in frozen embryo transfer cycles.

## Key findings

- Women over 35 had lower clinical pregnancy, implantation, and live birth rates.
- Transferring more embryos was linked to higher clinical pregnancy and live birth rates.
- High-quality embryos improved outcomes, while fragmented or uneven embryos reduced success.

## Abstract

To investigate the effects of maternal age, the number of transferred embryos, and embryo quality on pregnancy-related outcomes in frozen-thawed embryo transfer cycles.

A retrospective cohort study was conducted on 1031 frozen-thawed embryo transfer cycles enrolled at our hospital from January 2015 to December 2021.

In the pregnant group, maternal age was significantly lower compared to the non-pregnant group; additionally, both the number of transferred embryos and the number of high-quality embryos transferred were significantly higher in the pregnant group. Women older than 35 years exhibited significantly lower clinical pregnancy rate (p < 0.05), implantation rate (p < 0.001), and live birth rate (p < 0.01). A higher number of transferred embryos was associated with significantly increased clinical pregnancy rate (p < 0.001) and live birth rates (p < 0.001). When transferring two embryos, higher numbers of 7–9 cell embryos (p < 0.01) and grade 1 embryos (p < 0.001) were positively correlated with improved clinical outcomes, while increased transfers of fragmented (p < 0.05) and uneven embryos (p < 0.05) were negatively associated with these outcomes.

Maternal age, the number of transferred embryos, and embryo quality significantly influence pregnancy outcomes in frozen-thawed embryo transfer cycles. Clinicians should carefully tailor transfer plans based on individual patient characteristics and select optimal embryos for transfer to maximize success rate.