Male infertility was involved in one in every three rounds of IVF in 2020, with most of those men having no idea what affected their potency.
Some 20 percent of IVF rounds in 2020 were due to an infertile man, with another 11.2 per cent due to both a man and woman being infertile within a couple, the Assisted Reproductive Technology in Australia and New Zealand 2020 report from the University of New South Wales (UNSW) found.
When looking for an underlying cause, three-quarters of infertile males were left undiagnosed.
"(That) reflects our lack of understanding of the reasons for poor semen quality," Fertility Society of Australia and New Zealand President Luk Rombauts said.
Another seven per cent were attributed to previous vasectomies, and 2.4 percent had turned to IVF after receiving treatment for cancer.
Fertility research previously focused solely on women, despite men playing an equal part in conceiving a baby, Rombauts said.
As more data was collected on the causes of male infertility, scientists stood a better chance of understanding its impact, he said.
The results show more research and education are needed, and it's likely genetic studies could reveal risk factors for sterility.
Overall, 96,000 IVF cycles were performed in Australia and New Zealand in 2020, resulting in 18,462 new babies.
That's a 7.6 percent increase since 2019 and means one in 18 babies born in 2020 in Australia were conceived using IVF.
The COVID-19 pandemic may have had a dampening effect on the number of births, as health restrictions led to IVF being limited in some states, University of New South Wales public health researcher Prof. Georgina Chambers said.
Genetic testing, which allows parents to test embryos for chromosomal errors and genetic diseases, was used by about one in 10 IVF cycles in 2020.