It depends on how much mould is getting into the house. If she stays out of the basement there is little to worry about except when the baby is big enough to go into the basement. Mould does not seem to affect the baby in utero but will drag down the immune system of the mother over a period of time.
There is a good neurological trick to stimulate the immune system to resist mould is by tapping the dorsal vertebra number 3, then number 9 and then the lumber 4. Do this in the order listed for a few days then once weekly and there will a greater resistance to moulds.