Does your hair grow thicker while you are pregnant?
Doris Day, MD
New York University
Some people do notice that their hair can be thicker and fuller when pregnant, and this is due to a hormonal fluctuation.
What happens? Your hair has three cycles of growth: it has a growing phase, a resting phase, and a falling out phase. Sometimes with the hormones and the changes in pregnancy, your hair stays in that growing phase longer. Because you have more hair in that growing phase, your hair looks thicker and fuller and grows longer. Often it's more shiny as well.
Three to four months after pregnancy, when those cycles shift back, your hair starts to shed as you revert back to your normal hair cycles.
If all your hair grew in the growing phase at the same time and then shifted to the resting phase, every two to 10 years or so you would go bald completely. But fortunately that pattern is not synchronized. So about 90% of your hair is growing and 10% is resting or falling out. When that patterns shifts, you might notice that your hair looks fuller for a while, but there is a price to pay on the other side. It will balance back out.