Why am I losing so much hair after giving birth?

Q: I started losing a ton of hair a few weeks after my baby was born. What causes this, and when will it grow back?

A: "You can thank estrogen for both your lustrous locks during pregnancy and the greater-than-normal hair loss after childbirth," says dermatologist Debra Jaliman, M.D., assistant clinical professor at Mount Sinai School of Medicine in New York City. Normally, your hair has three cycles: growing, resting and falling out. During pregnancy, high estrogen levels cause nearly all your hair to be in the growing phase. Once you give birth, the hormone takes a nosedive, triggering an above-average amount of hair to switch to the falling-out stage.

The good news is that by the time your baby is 6 months old, you can expect to have regained your full head of hair, according to Jaliman. In the meantime, a shorter haircut or "volumizing" hair products such as mousse may help your locks look fuller. Another safe remedy, even for breastfeeding moms, is to take a 600-microgram biotin supplement, says Jaliman. "Biotin is a B vitamin that 'coats' each strand of hair, making it thicker," she explains. The hair-loss medication Rogaine is another option, although it is not recommended for breastfeeding women.