Q. I have just found out that I am in early pregnancy and wonder about colouring my hair. Do you have any advice on options? A. Many pregnant women prefer not to dye their hair until after the first 12 weeks of pregnancy, when the risk of chemical substances harming the baby is much lower, according to NHS Choices (www.nhs.uk).

However, NHS Choices points out that ‘the chemicals in permanent and semi-permanent hair dyes are not highly toxic. Most research, although limited, shows it’s safe to colour your hair while pregnant. Some studies have found that very high does of the chemicals in hair dyes may cause harm. However these doses are massive compared with the very low amount of chemicals a woman is exposed to when colouring her hair.’

This advice does not, however, distinguish between different types of colouring. Permanent or semi-permanent colour involves leaving the product on the scalp, through which it may be absorbed into the bloodstream. This is not the case with highlights of lowlights.

If you do decide to colour your hair yourself, you can reduce the risk by following these simple guidelines from the NHS:

• Wear gloves

• Leave the dye on for the minimum time

• Work in a well-ventilated room

• Rinse your scalp once the dye is applied

Henna, a semi-permanent pure vegetable dye, is a safe alternative to a rinse.

Another consideration is irritation: in one UK questionnaire-based survey, nearly half the 1800 subjects had used hair dye (which included rinses and lights) once or more, mostly women who had first tried colouring their hair around 25. Of those, 14 per cent reported developing eczema-type reactions, with three per cent saying they had experienced swelling under the skin.

For pregnant actress Tamsin Egerton, whose dark mane is usually shades of corn and gold, Charles Worthington Colour Revive Toning Mousse in Violet Toning is the solution. Tamsin tweeted that ‘Not being able to dye my hair over months is pretty rubbish. BUT I’ve just discovered Violet Toning Mousse & it’s awesome!’ Charles Worthington Colour Revive Tinted Mousse, available in Clear Gloss, Violet Toning, Blonde, Light Brown and Dark Brown, £9.99, at www.boots.com.

We would also recommend you consider Color Wow! Root Cover Up, a brush-on mineral powder that can prolong the length of time between colour sessions, or you can use it to give wonderful variations on coloured or natural hair. Color Wow! Root Cover Up, in blonde, platinum blonde, light/medium/dark brown, red, black, £28.50 at www.victoriahealth.com.