# Telomere length in relation to fecundability and use of assisted reproductive technologies: the Norwegian Mother, Father, and Child Cohort Study

## TL;DR

This study found that telomere length is not a reliable indicator of fertility or the need for assisted reproductive technologies in a large Norwegian cohort.

## Contribution

The study is the first to investigate telomere length's association with fecundability and ART use in a large population-based cohort.

## Key findings

- Telomere length was not associated with fecundability or infertility in either women or men.
- Longer telomere length in men was linked to a higher likelihood of using ART.
- Genetically predicted telomere length showed no significant associations with the studied outcomes.

## Abstract

In women, shorter telomeres have been reported to be associated with conditions such as endometriosis and polycystic ovary syndrome, whereas other studies have reported the opposite. In men, studies mostly report associations between shorter telomeres and sperm quality. To our knowledge, no studies have thus far investigated the associations between TL and fecundability or the use of ART.

This study is based on the Norwegian Mother, Father, and Child Cohort (MoBa) Study and uses data from the Medical Birth Registry of Norway (MBRN). We included women (24,645 with genotype data and 1,054 with TL measurements) and men (18,339 with genotype data and 965 with TL measurements) participating between 1998 and 2008. We investigated the associations between leukocyte TL and fecundability, infertility, and the use of ART. We also repeated the analyses using instrumental variables for TL, including genetic risk scores for TL and genetically predicted TL.

Approximately 11% of couples had experienced infertility and 4% had used ART. TL was not associated with fecundability among women (fecundability ratio [FR], 0.98; 95% confidence interval [CI], 0.92–1.04) or men (FR, 0.99; CI, 0.93–1.06), nor with infertility among women (odds ratio [OR], 1.03; CI, 0.85–1.24) or men (OR, 1.05; CI, 0.87–1.28). We observed an increased likelihood of using ART with increasing TL among men (OR, 1.22; CI, 1.03–1.46), but not among women (OR, 1.10; CI, 0.92–1.31). No significant associations were observed using the instrumental variables.

Our results indicate that TL is a poor biomarker of fecundability, infertility and use of ART in MoBa. Additional studies are required to replicate the association observed between TL and ART in men.