Hair and How It Changes During and After Pregnancy

Hair changes during pregnancy are very common. Many women have heard both horror stories of hair loss and hopeful stories of healthy, lengthening locks. However, every woman is different and the hair changes that affect you may not be the same as those affecting another woman. This article discusses the most common hair changes during pregnancy, when they occur, and what you can do about them. Three common hair changes include increased scalp hair growth, increased body hair growth, and the falling out of hair that often occurs after birth.

Scalp Hair Growth

Before delving into this topic, it should be noted that hair undergoes three main phases of life: the anagen phase, the catagen phase, and the telogen phase. The anagen phase is a phase of active hair growth and usually lasts anywhere from 2-5 years. The catagen phase is a transitional phase lasting several weeks. The telogen phase, the last phase, is a resting phase when hair gets ready to shed and this can last around 3 months.^[1]

Hair growth in pregnancy

During pregnancy, hair tends to stay in the anagen phase longer, which may be due to higher levels of the hormone estrogen in the body.^[2] This allows hair to continue growing for a longer period of time, resulting in greater hair density as well as longer hair. Not only does hair remain in a longer growth phase, but individual hairs also appear to be thicker in pregnancy. In 2003, two researchers demonstrated that hair shaft diameters were significantly greater in a group of 12 healthy, post-term pregnant women compared to a group of 13 non-pregnant women.^[3]  Many women experience a growth in scalp hair that is seen throughout pregnancy. However, this may not be the case for everyone.

Hair loss in pregnancy

There have been a few reports of hair loss changes during the end of pregnancy, including frontoparietal recession (hair loss from the area where the frontal hairline meets the face back to the crown of the head) and diffuse hair loss. The former is a type of hair change that often represents male-pattern hair loss and is more common in women with a family history of this type of condition. Diffuse hair loss can also occur and is thought to result from high levels of steroids in the body, which tend to suppress normal female hormone pathways. Increased steroid levels are thought to be due to placental production of corticotrophin-releasing hormone (CRH), which stimulates the adrenal glands to make more corticosteroid.^[4] It should be noted that these two scalp hair changes are infrequently reported and that hair growth is more common in pregnancy.^[1]

Increased Body Hair Growth: Hirsutism

Hair tends to increase not only on the head but also all over the body! Women can experience increased hair growth in any of the following areas: upper lip, chin, cheeks, jaw lines, arms, legs, back, and genital areas.^[1] When women experience increased hair growth in a male pattern, this is known as hirsutism. These changes actually occur in most if not all pregnant women to varying degrees. However, women with darker hair or naturally more body hair in the pre-pregnant state tend to experience this more.^[5] The reason for male-pattern hair growth during pregnancy is thought to be due to androgen (male hormone) production by the placenta and ovaries as well as increased levels of cortisol. If there is excessive hair growth, there could be an underlying medical condition such as tumors which can secrete androgens or undiagnosed polycystic ovarian syndrome.^[1] An excessive amount of hair growth is much less common than physiological (normal and expected) hirsutism.

Most physicians do not recommend permanent treatment for hirsutism during pregnancy as most lanugo (soft) hairs shed within 6 months of delivering. Some coarse/long hairs may remain and can be treated with shaving, waxing, laser hair removal and/or electrolysis. Shaving, waxing, and plucking are typically recommended while pregnant as the safety of electrolysis and laser hair removal during pregnancy is unknown and therefore the usual recommendation is to pursue these therapies after giving birth.^[6]

Hair Loss Postpartum: Telogen Effluvium 

Telogen effluvium is a term that means hair shedding due to more hairs being in the telogen (resting phase) of the hair cycle. It is proposed that many hairs previously in the anagen phase rapidly convert to the telogen phase after the baby is delivered, leading to large amounts of hair fall. The process usually begins 2-4 months after delivery and lasts for 3-6 months.^{[1, 7]}

There are several theories for why this distressing phenomenon occurs. One theory suggests that the pituitary gland (which plays a role in the creation of sex hormones) is not working as well after pregnancy due to high levels of estrogen produced during pregnancy. Once estrogen levels fall at the end of pregnancy, the pituitary gland may not be able to “pick up the slack” as quickly as it should, and the body experiences low estrogen levels. Other factors such as physiological stresses (blood loss, birthing process) and the secretion of the hormone prolactin with breastfeeding may also play a role.^[1]

Fortunately, this process is self-limited and does not usually require treatment. Most women will experience a full recovery from the hair loss although this may take up to 15 months. Reassurance, proper hair, scalp, and nutritional care are the recommended treatments.^[1,7]