Male Fertility Worsens With Age Just Like Women's, With a Man's Biological Clock Ticking Faster After 50

The older a man is, the harder it is for him to conceive with a partner, according to researchers who say a man's age should be considered as much as a woman's when it comes to fertility.

Men aged over 50 who took part in the study were "significantly" less likely to conceive or have a baby with their partner than those aged 40. The research published in the journal Human Reproduction also showed the likelihood that a man could have a baby with his partner dropped by 4.1 percent every year he aged, regardless of the woman's age. The chance of conceiving meanwhile fell by 3 percent each year, and the risk of miscarriage rose by 4.5 percent.

The study involved 1,506 couples struggling to conceive for an unknown reason, who had 2,425 cycles of treatments at the Monash IVF fertility clinic in Australia. The participants had undergone at least one round of IVF, where an egg is taken from a woman's ovaries and fertilized with sperm in a lab before being inserted into the womb, and intracytoplasmic sperm injections, where the egg is injected individually with a sperm.

The men in the study were 46 years old on average, ranging from 27 to 77, and had normal sperm, while the women were between 21 and 48 years old and were 37 on average. In order to avoid skewing the results, women who had gynecological problems, including endometriosis, were excluded from the study, as were couples using frozen eggs and sperm, or who had genetic diseases.

In their paper, the researchers wrote: "The effect of male age on the outcomes of infertility treatments is controversial and poorly explored. In contrast, fertility is known to decline significantly with female age beyond the mid-30s, and reduced oocyte [egg] quality plays an important role."

As men age, they explained, it is thought that their sperm becomes more vulnerable to DNA damage.

The authors acknowledged the study was limited because it is difficult to uncover the cause of fertility problems, and the results might relate to a wider population due to the strict selection criteria.

Study co-author Beverley Vollenhoven, professor in Obstetrics and Gynaecology at Monash Health said in a statement: "From a clinical point of view, we've always concentrated on female age in fertility because we know all about it.

"Menopause in women defines a distinct period in their life. Males do not have menopause. Until now we haven't really talked about male age and its effect on the chances of pregnancy."

Vollenhoven said: "The man's age is very important. In times past there hasn't been a great deal of discussion about that. I am also talking about male age in relation to the increased risk of autism, dwarfism and Downs.

"It's important that people understand what they may face before they start. You don't want to be pessimistic, but you don't want to be overly optimistic or offer false hope."

Lead author Fabrizzio Horta, a clinical embryologist from the School of Clinical Sciences and Monash IVF and Monash University Ph.D. candidate, said in a statement: "The findings are very important, as this has not been previously rigorously researched.

"There's always been more interest in and knowledge of the female side—male fertility has been an issue in hiding."

He said: "We did not expect that the effect of male age would still occur when they partnered with a young woman."

As the average age when men try for children rises, such problems should be factored in when helping couples trying to conceive, said Horta. That might include the option of freezing sperm.

Professor Vollenhoven said: "People need to be given choices," adding: "the patients I see are the patients who have a problem."