It isn’t just women and fertility: most mammals, from rabbits to elephants and whales, live for about one billion heartbeats. Their lifespan and metabolism vary widely, but the number of heartbeats is about the same.
Do you see the outlier? Humans live around twice as long as they “should”, measured in heartbeats. Even our close ape relatives still live around one billion heartbeats, not two. Why is this? One theory is the “grandparent” or “elder” hypothesis. Because humans have large brains and depend on exosomatic knowledge being transmitted across the generations, populations with long-lived elders who accumulate this knowledge and pass it on to the two next generations are more successful than those who die off shortly after their reproductive years. Tribes with tribal elders out-compete those without them.
What about chickens? They aren’t mammals, and birds live much longer than they “should ” compared to mammals. It’s probably the mitochondria.