Yes, pregnant can do sealing on the hair, provided that the sealing is only with keratin and the procedure is done after first trimester of pregnancy.
As long as the product is applied only to the hair strands, it should not be absorbed by the body and in that case the sealing can be performed during gestation.
However, there is a chance that the product will formalin in its composition or other chemicals that are not known or guaranteed to be safe for use by the pregnant woman.
In addition to being carcinogenic, formalin evaporates easily and can be aspirated by the woman and reach the bloodstream, impair the development of the fetus.
Learn more at: I'm breastfeeding, can I do sealing in my hair?
The products used in the sealing can not resorcinol, lead or hydroquinone in their formulas.
When in doubt, look at the product label and check for any warnings when using during pregnancy or show the label for your obstetrician.
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