A woman's body undergoes significant changes during pregnancy, a process that is heavily influenced by hormonal fluctuations. These changes also affect the scalp. In this article, we will explore all the effects of pregnancy on hair.
Pregnancy and hormones: what happens?
If pregnancy has such significant impacts on the body, it's due to the high hormonal activity that occurs during this period. During pregnancy, the production of estrogen in the body increases and can be multiplied by 1,000. These hormones are produced by the corpus luteum, which is the fertilized ovarian follicle, and stimulate the production of new cells, particularly in the uterus. This allows the uterus to stretch so that the baby has room to grow. Estrogens also increase blood volume so that the embryo can receive all the nutrients and oxygen it needs.
We also observe a significant increase in the rate of progesterone in the body during pregnancy. This hormone could potentially reduce the risk of miscarriage. Indeed, studies suggest that some miscarriages result from insufficient production of progesterone during pregnancy. It also works in synergy with estrogens to stimulate the development of mammary glands in preparation for lactation.
The hair's response to hormonal fluctuations.
Many pregnant women notice an improvement in the appearance and texture of their hair. This improvement is correlated with the increased production of estrogen and progesterone in the body. Indeed, estrogens are capable of binding to certain specific receptors present in the scalp that have an affinity for these hormones. These receptors trigger a cascade of reactions, ultimately leading to a speeding up of the anagen phase. This phase corresponds to the hair growth period in the hair cycle. Progesterone, on the other hand, is responsible for the inhibition of the activity of 5-alpha reductase, an enzyme modulating the conversion of testosterone into dihydrotestosterone (DHT). However, DHT acts at the level of hair follicles by shortening the lifespan of hair and accelerating hair cycles. That's why pregnant women often notice faster hair growth.
Progesterone is capable of binding to certain receptors belonging to the nuclear receptor family of the sebaceous glands, organs present throughout the skin, including the scalp. This binding triggers several biological mechanisms, among which the activation of Protein Kinase C (PCK). This in turn stimulates sebum production by increasing the activity of Phospholipase A2 (PLA2), an enzyme that breaks down membrane phospholipids into free fatty acids and lysophospholipids, precursors of sebum. As a result, women tend to find their hair shinier during pregnancy.
However, it's important to note that we cannot make generalizations. Some pregnant women notice no changes in their hair. Sensitivity to hormones varies from person to person, as does the amount of hormones synthesized.
EKMEKCI T. & al. The changes in the hair cycle during gestation and the post-partum period. Journal of the European Academy of Dermatology and Venereology (2014).
CASTELO-SOCCIO L. & al. A review of the use of biotin for hair loss. Skin Appendage Disorders (2017).
MECZEKALSKI B. & al. Hormonal effects on hair follicles. International Journal of Molecular Sciences (2020).