Thanks for your query,
In third trimester of pregnancy
there is a collection of milk in milk glands of breast due to hormonal
changes taken place causes breast to engorged then what it was.
The surrounding skin has to stretch to cover that mass resulted in to rashes due to stretch.Don't stress
for skin disease.avoid to collect perspiration in folds of breast
just go on wearing loose cloths with talcum powder sprinkle on it will prevent skin disease.have a nice day.