Recently, we pointed you to a study that said that older fathers create a genetic situation that can create children with lower IQs. Now, more news for men considering fatherhood in their later years: the gears in your biological clock might be losing function past the age of 41.

Paula Fettback, a researcher at the Huntington Medicina Reproductiva clinic in Brazil, reported that there’s a 60% chance of pregnancy with a 41 year old male, and 35% with a 45 year old.

Men continually make “fresh” sperm (try reading that without getting particular sensory nastiness in your head), but all the internal junk that makes sperm gets older too. Just like grandpa’s a little off when you play catch with him now, his chefs are also a little off now when they cook their man-chowder. Yeah, I just said that. Webby, here I come.

Of course, this shouldn’t stop older men from fathering if they feel they’re up for the job. There are many factors that impact pregnancy and researches admit that a viable egg is more important than viable sperm. But, with more and more evidence pointing to lower chance of reproduction and higher rates of defects when sperm comes from an older man, this might be what some men need to scare themselves into serious commitment earlier. Hey, fear’s not always a bad thing.