Why does a baby's first head of hair fall out?
Basically, for the same reason you find yourself shedding like a Saint Bernard after giving birth: a drop in hormones. "High estrogen levels in your body during pregnancy cause both your and your baby's hair to grow, with less resting or shedding," says Jennifer Shu, M.D., an Atlanta pediatrician and coauthor of Heading Home With Your Newborn. Postpartum, your estrogen levels plummet -- and so do your baby's because he's no longer getting his hormones from you.
You both enter a shedding stage called "telogen effluvium." This lasts about six months for your baby, possibly longer for you. Will your child become as bald as Bruce Willis? It depends on his hair's texture and whether he sits up early (then he won't spend as much time rubbing his head against mattresses and activity mats). All the while, though, new hair is sprouting. Just don't be shocked if this do is way different -- most infants' second headful is darker and coarser.
Is having a baby painful for other animals?
Since most mammals don't bellow during labor (except for us and a few others, such as Sumatran rhinos), it's easy to assume they're not in pain. But, says Terri Roth, Ph.D., a reproductive physiologist at the Cincinnati Zoo, "it just isn't to their advantage to make a big production. They're trying to stay quiet and hidden, especially from predators." Our animal sisters are suffering, though.
Consider dogs. The first time they give birth, they're often in such pain that they have to be stopped from biting their emerging puppies, says breeder Donna Pitt of Newport, Virginia. Most other mammals, from guinea pigs to giraffes, will pace, lie down and get up repeatedly, and be unable to sleep when delivery is imminent, Roth says. Some paw the ground. "Eventually they start straining when they go into labor. You can see their hind legs stretch out behind them, and the muscles on their sides contracting," she explains. The only mammals that seem to escape this ordeal are those whose newborns are tiny and presumably slip out easily -- bears and kangaroos, for instance. (Lucky them.)
And how about birds? Could laying an egg -- in some cases one a fifth the mom's size -- hurt, too? You bet. Most birds breathe hard while laying; their bills open and shut and their tails bob, says Roth's colleague David Oehler, an ornithologist. Afterward, they enter a motionless "recovery phase." (During which, presumably, they're pining for a little Tylenol.)