Here is an article about maternity wears like the maternity sweaters, maternity jumpsuits, maternity rompers and jumpsuits. Previously women did not pay much attention to their pregnant months. They just preferred wearing loose fitted clothes.
It was not until the middle of the day. European women used to wear dresses. When it's time to get pregnant, it's time to get pregnant. They used a type of gown which was less and had many folds. Maternity dresses came into the vogue mainly during the Georgian period.
But gone are those time when women have to wear the same dresses even during their pregnancy. Maternity jumpsuits, maternity dungarees, maternity sweaters etc.