When: One to five months after delivery
Why: "Around the fourth month after Lily was born, I had an incredible amount of hair falling out," says Missy Jacobs, of New York City. Don't worry -- there's no need to invest in Rogaine. "Due to hormonal changes in pregnancy, hair becomes thicker and fewer hairs fall out," Dr. Karjane says. "After delivery, these effects go away. Although the amount of hair loss can be shocking, rarely do women experience extensive hair thinning." Within several months to a year, you should be back to normal.