Hair can become thicker

Your hair has a natural life cycle. Each individual hair grows, then rests for 2 or 3 months before being pushed out by a new hair growing in that follicle (the tube-shaped sheath that surrounds the hair beneath the skin). In pregnancy, this cycle changes.

Many women experience their hair feeling thicker at around 15 weeks of pregnancy.

This is not because each hair strand itself becomes thicker, but because the hair stays longer in the growing phase of its cycle, which means that less hair falls out than usual. This is due to an increase in the hormone oestrogen.

Hair can become thinner

Some women experience more of their hair falling out during pregnancy. This is due to a decrease in oestrogen, which may happen as a result of the following:

• stopping the oral contraceptive pill
• experiencing an abortion, miscarriage or stillbirth
• a hormonal imbalance during pregnancy

It is also common for women to experience hair loss after pregnancy when their oestrogen returns to normal levels. This causes the additional hair from the growth phase to change to the resting phase, which then falls out more than usual, until around 3-4 months after your child is born.

This hair loss is usually nothing to worry about – your hair growth will return to normal by the time your baby is around 12 months old. If you feel your hair loss is excessive, or your hair growth has not returned to normal by 12 months, speak to your doctor.

Should I dye my hair during pregnancy?

Using hair colour, or ‘dye’, is not thought to cause harm to your developing baby because your hair doesn’t absorb enough harmful chemicals to affect you or your baby. The amount of toxic chemicals in hair dye is not high.

However, as there is not a lot of research into the use of hair dye and pregnancy, you may prefer to delay colouring your hair until after the first trimester (first 12 weeks of pregnancy) is complete.

Other things you can do to minimise your exposure to hair-colour chemicals:

• wear gloves if you dye your hair yourself
• ensure you don’t leave the hair dye in for longer than necessary before rinsing
• colour your hair in a room that is well ventilated
• rinse your scalp well afterwards
• follow the directions on the packet of hair dye
• don’t mix different hair colour products
• do an allergy (patch) test before you dye your hair

Be cautious if using other chemical treatments on your hair. For example, some hair straightening treatments contain the chemical formaldehyde. While there’s no evidence that it can harm unborn babies, it is a known carcinogen and should probably be avoided.

If you’re unsure, speak to your doctor about whether your hair treatment is safe for use during pregnancy.

Where to seek more information

• Call Pregnancy Birth and Baby on 1800 882 436 to speak with a maternal child health nurse.