Yes. Up to 90 percent of pregnant women notice this to some degree.
The vast majority of pregnant women will notice darkening of some part of their body, whether it be the areolae, labia, linea nigra (dark line from pubic hair to belly button), or face. Many of these will lighten again after delivery but most will not completely revert back to their pre-pregnancy appearances. Cool fact: the areolae and linea nigra both darken to help your baby locate the breast while breastfeeding. Mother Nature has her reasons!
Brownish spots on the face are collectively called chloasma, or the “mask of pregnancy.” These are harmless and usually fade after pregnancy, but spending time in the sun or tanning will make these darker so be sure to use sunscreen. If you want to treat these areas, you should wait until after you deliver. Treatments include chemical peels and bleaching agents and should be used under the supervision of someone who is appropriately trained.
If you notice new moles with a suspicious appearance at any time, make sure you mention it to your doctor or midwife.