Because we don't know the effects of cosmetic procedures on the baby, it is not recommended to have any cosmetic procedures while pregnant or breastfeeding.
Cosmetic procedures are not tested on pregnant or breastfeeding women, so we have no way of telling what the safety profile of these treatments is, including all injectables and laser procedures.
It is known that Botox for example can drift from an injected area to other areas.
So, what does one do? Use an excellent broad-spectrum sunscreen daily to prevent more sun damage and wrinkling, as well as hyperpigmentation and avoid sun exposure. The hormones present during pregnancy and breastfeeding make women more likely to develop melasma. Sunscreens will help prevent this.
Since there is a greater chance of hyperpigmentation under the action of hormones, laser treatments can potentially have more adverse effects. Also, numbing medicine is used before the procedure, small amounts of which could potentially be absorbed into the body.
For many cosmetic procedures, taking a medication to prevent cold sore breakouts is necessary for several days before and after a procedure.
Skin texture is also different under the influence of hormones. Some women have perfect skin, and some break out with acne quite a bit. Rosacea may also be more active at this time.
Wait until you are done breastfeeding to have cosmetic procedures. We just don't have data on their safety during pregnancy or breast feeding.