Yes, it is very normal, the darkening is usually from hormonal changes during pregnancy, and for most mums it does fade gradually on its own after birth, so try not to stress too much about it. Someone in my mum group mentioned that keeping the area moisturised, staying hydrated, and using sunscreen if the skin is exposed can help speed things along a little. That said, some mums find the skin takes longer to bounce back depending on how the body recovers, so it is worth being patient and giving it a few months before expecting big changes. If the darkening seems unusually persistent or comes with other skin changes, it is always a good idea to check with your doctor or a dermatologist just to be sure nothing else is going on.