Male age and fertility decline and fertility: what the evidence says

What does the evidence say about male age and fertility decline while trying to conceive?

1. Advanced paternal age is most commonly defined in research as older than 40 years at the time of conception, though the exact cutoff remains debated among researchers. 1
2. One study found a fivefold increase in the time it took to achieve pregnancy when the male partner was older than 45, and men over 45 were about 4.6 times more likely to still not have achieved pregnancy after a year of regular unprotected intercourse. 1
3. Sperm quality changes measurably with age: one analysis found the DNA Fragmentation Index, a measure of sperm DNA damage, reached 32.0% in men over 45 compared with 15.2% in men under 30, and researchers note the risk of sperm DNA damage roughly doubles between ages 25 and 55. 2
4. In IVF settings, each additional year of paternal age was associated with an 11% increase in the odds of not achieving pregnancy and a 12% increase in the odds of not having a successful live birth. 3
5. At the molecular level, researchers have identified dozens of proteins in sperm that change with age, including several tied to energy production and to the acrosome structure sperm need to fertilize an egg, offering a possible biological explanation for why older sperm can perform less well even when a standard semen analysis looks normal. 4

What to know about male age and fertility decline while trying to conceive

• If you're just beginning to try to conceive and the male partner is under about 40, age is unlikely to be a major factor on its own, though a generally healthy lifestyle supports sperm quality at any age.
• If conception hasn't happened after several months of trying and the male partner is 40 or older, this is a reasonable point to loop in a provider, since time-to-pregnancy research shows a real, measurable slowdown starting around this age.
• If you're pursuing fertility care such as IUI or IVF, paternal age is one of the factors a fertility specialist will weigh alongside female age, since studies show each additional year of paternal age is linked to modestly lower success rates.