When you find out you’re pregnant, there’s more to look forward to than the birth of your child. Prepare yourself for 9 months of good hair days, too.
"I always tell my patients that their hair will be the best it's ever been -- lush, full. Enjoy it!" says Paradi Mirmirani, MD, a dermatologist with Kaiser Permanente in Vallejo, Calif.
Hair normally grows in three phases: active growth, resting, and shedding. During these phases, people typically shed 100 hairs every day. When you're pregnant, the extra hormones coursing through your body shift your hair cycle. Your hair grows or stays on your head and doesn’t shed. This is why your hair seems longer and thicker than usual.
Some research also suggests that hair strands actually thickens during pregnancy. "The diameter of the hair increases," Mirmirani says. "We measured hair diameter in the third trimester and after pregnancy, and it's definitely thicker during pregnancy."
Sometimes, a woman's hair becomes more or less curly during or after pregnancy.
"We don't understand the exact mechanism," Mirmirani says. "There's a lot of thought about whether hormones during pregnancy can alter the shape of the hair follicle. The shape of the follicle dictates the shape of the hair fiber."
If you normally dye, highlight, perm, or relax your hair, you may wonder whether to take a break during pregnancy. Some doctors recommend stopping, while others say that it's OK to continue. Still others say that treatments should be avoided in the first trimester, but they're OK later in pregnancy.
Why the difference of opinion? Very few studies have examined the effects of dyes and other hair chemicals in pregnant women. Still, there's a chance that harsh chemicals may be absorbed through your scalp during treatments and passed along to your growing baby.
"We truly don't know if anything is absorbed internally, but you have many pores that are deep on the scalp, and there's always the potential, especially if the scalp is irritated," says dermatologist Nia Terezakis, MD, a clinical professor at Tulane University. "The fewer chemicals, the better."