Read labels. Read labels in pregnancy and if n doubt, ask your gyn if you have any questions about products to use on your hair.
Tell your doctor. Women may experience hair loss in pregnancy. This is can be secondary to hormonal changes as your pregnancy continues, but it can also be a sign of other underlying medical conditions. Metabolic conditions, such as thyroid disease need to be ruled out to ensure that this not the culprit for your hair issues. Continue your prenatal vitamins and calcium intake during these vital months of your life.