# Divergent long-term trends in semen quality and reproductive hormones across the COVID-19 pandemic era in infertile men: an age-stratified retrospective study

## TL;DR

This study found that semen quality and hormone levels in infertile men declined during and after the pandemic, with changes lasting over two years.

## Contribution

The study reveals long-term, age-dependent changes in semen morphology and testosterone levels in infertile men during the pandemic era.

## Key findings

- Normal sperm morphology decreased significantly during the pandemic, with 55.1% of men below the WHO threshold in Post-Phase 2.
- Testosterone levels dropped modestly but remained above hypogonadism thresholds for most men.
- These changes persisted for over two years post-pandemic without returning to pre-pandemic levels.

## Abstract

Male reproductive dysfunction has been reported during the acute phase of COVID-19. However, the long-term patterns in semen quality and hormonal parameters across the extended pandemic and post-pandemic periods, and whether these patterns differ by age, remain poorly characterized. This large-scale, retrospective study was conducted to delineate these trajectories in infertile men.

Among 90,125 records, normal sperm morphology showed a sustained deficit: the proportion of men with morphology ≥ 4% declined from 88.9% pre-pandemic to 55.1% in Post-Phase 2 (p < 0.001), with nearly half falling below the WHO clinical threshold (4%). Serum testosterone decreased modestly from 4.46 to 4.19 ng/mL (6.1% reduction; (p = 0.006) but remained above the hypogonadism threshold for most men. These alterations persisted two years into the post-pandemic period without returning to pre-pandemic baselines.

The COVID-19 pandemic was associated with persistent, clinically meaningful deficits in normal sperm morphology and a moderate, non-hypogonadal testosterone suppression, with distinct age-dependent patterns. These findings underscore the need for age-stratified reproductive health surveillance following major population-level stressors.

The online version contains supplementary material available at 10.1186/s12610-026-00309-1.