# Polycystic ovary syndrome (PCOS) affects relative embryo morphokinetics observed by time-lapse imaging: an observational study

## TL;DR

This study finds that embryos from women with PCOS show altered relative developmental timing, which may affect embryo quality.

## Contribution

The first study to examine the influence of PCOS on relative embryo morphokinetic ratios using time-lapse imaging.

## Key findings

- PCOS embryos showed longer intervals during specific cell cycle stages compared to controls.
- Relative cleavage synchronicity ratios were altered in PCOS embryos, suggesting potential developmental differences.
- Absolute embryo development times were not significantly affected by PCOS.

## Abstract

To characterise the effect of polycystic ovary syndrome (PCOS) on embryo morphokinetics via time-lapse imaging, including absolute time points, relative time intervals, and ratios representing cleavage synchronicity.

This single-centre retrospective observational study examined patients aged 18–45 years undergoing in vitro fertilisation/intracytoplasmic sperm injection with time-lapse imaging (09/2016–12/2019; n = 1433 two-pronuclear oocytes). A group with PCOS (n = 48 embryos) was compared to a control group with uterine, tubal factor or idiopathic infertility (n = 400 embryos). Times from the two-cell stage to blastocyst expansion, eight intervals for embryonic cell cycle (ECC) duration and synchronicity and four cleavage synchronicity (CS) and DNA replication time ratios were analysed.

PCOS patients were younger (P = 0.023) with higher anti-Müllerian hormone levels (P < 0.001) than controls. No statistically noticeable influence of PCOS on absolute times was observed. The intervals from the 3- to 4-cell (synchronicity of cell cycle 2, s2; P = 0.013), the 5- to 8-cell (synchronicity of cell cycle 3, s3; P = 0.032) and the 4- to 8-cell stage (ECC3; P = 0.043) were longer in the PCOS group. The relative CS ratio from the 2- to 8-cell stage (CS2-8) was lower (P = 0.003) and from the 2- to 4-cell stage (CS2-4) was higher (P = 0.001) in PCOS embryos.

Whilst absolute times remained unaffected, relative morphokinetic intervals and ratios, potentially indicating poorer cleavage synchronicity, were altered in PCOS embryos. This is the first study examining the influence of PCOS on relative morphokinetic ratios.