Can I use mehendi to colour my hair during pregnancy?

My best friend used mehendi during pregnancy and her doctor said that as long as the formulation is pure and natural, there are no issues. Be sure to check the packaging because some henna brands use chemicals to enhance the colours, avoid those. Also, the doctor cautioned her against using black henna though. Apparently black henna contains a chemical called para-phenylenediamine (PPD), which is a chemical often used in hair dyes. Best to avoid black henna when you are pregnant. Even if have used it before pregnancy and never reacted to it, you might be more sensitive to it now that you are with child.