Hie mommies, im currently 34 weeks pregnant.i realize my underarms are getting darker..?? Is it normal? How to treat it?

sabi nila normal lang daw mommy sa panganay ko walang nag bago sa akin but in my second pregnancy lahat nangitim underarms,leeg pati singit ko ang itim kaya akala nmin baby boy magiging anak ko pero girl padin