Al Pacino, 83, is about to be a dad to a new baby. Robert De Niro, 79, just welcomed his 7th child. Do men have biological clocks?

Congratulations are in order for two Hollywood leading men. Al Pacino, 83, is welcoming a new baby with 29-year-old girlfriend Noor Alfallah, while 79-year-old Robert De Niro just introduced the world to his seventh child, his first with decades-younger partner Tiffany Chen. Pacino and De Niro may be able to have children, but their advanced age does make one wonder: do men have biological clocks that impact their fertility?

When it comes to fertility, a heavy emphasis is placed on the age of the woman, with studies suggesting that fertility begins to decline in one’s 30s, particularly after age 35. Dr. Jamie Grifo, director of NYU Langone Fertility Center and division director of reproductive endocrinology and infertility within the Department of Obstetrics and Gynecology at the NYU Grossman School of Medicine, previously told Yahoo Life, "Even with reproductive assistance, achieving pregnancy after age 45 is very slim — this is because the number of eggs and the quality of those eggs is very low.”

Yet men who have a younger partner don’t have to worry quite as much about their own age when it comes to having a biological child — at least, to an extent. Fertility does decline in men as they age, but not as dramatically as it does for women — and for different reasons.

Dr. Jane L. Frederick, a reproductive endocrinologist, tells Yahoo Life that men over the age of 40 are 30% less likely to conceive compared to younger men under the age of 30. Data also showed that it took older men longer to get their partner pregnant — a five times increase compared with men under 25.

Male fertility is an under-researched field, yet there are some findings to suggest male biological clocks do have a significant impact on the likelihood of a successful pregnancy. A 2017 study from Beth Israel Deaconess Medical Center and Harvard Medical School, for example, found that the chance of live birth decreased with older men, even if their partners were younger women.

While men often can have biological children much older than women can, their fertility is still impacted by age.

Age impacts the health of one’s sperm, says Dr. T. Mike Hsieh, the director of UCSD Men’s Health Center and professor of urology, who notes that “increased paternal age is associated with a decline in sperm count, sperm quality, semen volume, testosterone and ability for sexual activity or erectile dysfunction.”

But one reason for this decline may have to do with how healthy an individual is as a whole, explains Dr. Paul Turek, a urologist and expert on fertility in men. The older a man is, the more likely he is to be exposed to certain environmental factors or develop health conditions that impact fertility by affecting the DNA package of his sperm.

“Eggs try as hard as they can to ‘fix’ the DNA early on after fertilization, but if the load of damage is in excess of the egg’s capacity to repair it, then there will be no pregnancy or possibly a miscarriage,” he says.

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