A: It's usually a good idea to make sure your stylist performs a patch test (to check for sensitivity to the chemicals) and a strand test
(to verify processing times) anytime you have a chemical service, but especially if you are (or have recently been) pregnant. The hormones
released in the female body during pregnancy affect the body in various ways. Some women experience a thinning of the hair during or
immediately following pregnancy, some women find that perms given during pregnancy don't work as well (and in some cases not at all).
There's also the fact that many women become hyper-sensitive to chemicals that contact the skin. Your
hair's condition may change (drier, oilier, more porous, more resistant, etc.) which will effect how it processes and the results you will see.
A common effect among pregnant women is that the chemical smells that were previously only annoying become nauseating and intolerable.
In most cases, bleaching or dying the hair during pregnancy is fine, as long as you've tested to make sure
you haven't developed a sensitivity to the haircolor or bleaching agent. If the patch test shows any degree of sensitivity, then don't have the process.
In a patch test, your stylist will apply a small dab of the chemical (haircolor or perming solution) to an
area not usually visible (usually on the neck behind the ear) and leave it there for the normal length of processing time, then wipe it away
and wash the area. Then you wait for 24-48 hours and check the area for redness, or irritation. If after 48 hours there's no reaction or
irritation, you can feel safe in pursuing the chemical service.
Strand tests for color involve take a slender lock of hair from the head and using it as a swatch to be
treated with the chemicals to be used. This allows the stylist to know exact processing times needed for bleaching and coloring to achieve the color you want.
Most problems with pregnancy and hair are in sensitivity to the chemicals and smell of haircolor and perming
solutions, and in processing and results of processes like perms and straightening. It's uncommon to find a problem with the results of haircolor processes due to pregnancy.