Chromosomal polymorphisms in assisted reproduction: an analysis of 942 cycles

Abstract

The use of intracytoplasmic sperm injection (ICSI) has recently increased worldwide. The live birth rate per ICSI cycle is low, and over half of infertile couples remain childless. Chromosomal polymorphisms are up to five times more common in couples with infertility compared to the general population. We aimed to investigate the association between chromosomal polymorphisms and reproductive outcomes in couples undergoing ICSI treatment. We analysed 942 ICSI fresh and frozen embryo transfer cycles in 697 women who underwent karyotyping analysis using Giemsa-Trypsin-Leishman banding prior to assisted conception at the Fertility Centre of Lanka Hospitals, Sri Lanka, between 2016 and 2018. The primary outcomes were pregnancy, miscarriage, and live birth rates. We compared outcomes according to the presence or absence of chromosomal polymorphism in females, males and couples. There were 294 pregnancies (31.2%) recorded in the study; 130 suffered a miscarriage (13.8%), 13 were ectopic pregnancies (1.3%) and 151 resulted in a live birth (16.0%). The evidence from univariable and multivariable analyses (adjusted for age, BMI, ovarian reserve and treatment type) did not confidently identify a difference in pregnancy, miscarriage or live birth rates between couples with no chromosomal polymorphisms compared to couples where the female, male or both partners were carriers of a chromosomal polymorphism. Further, we did not identify a clear association between the presence of chromosomal polymorphisms and reproductive outcomes compared to participants without chromosomal polymorphisms. Wide CIs precluded the identification of clinically meaningful associations.

Lay summary: Infertility affects approximately one in eight couples worldwide. The use of intracytoplasmic sperm injection (ICSI), where the sperm is directly injected into an egg using a micromanipulator outside the body, has become particularly popular in recent years. However, the success rate remains low. In human cells, the genetic material is arranged in structures called chromosomes. Chromosomal polymorphism is a normal variation where the genetic material is arranged differently to the average individual and is more common in infertile couples compared to the general population. We analysed data from 942 ICSI cycles in 697 couples who underwent karyotyping analysis to assess the changes in chromosomes between 2016 and 2018. The pregnancy rate was 31.2%, with 16.0% of participants experiencing a live birth, while 13.8% of pregnancies resulted in a miscarriage and 1.3% were outside the womb cavity (ectopic). The evidence did not identify a clear association between the chromosomal polymorphism and the outcome of treatment.