From :
The fungus that is caused by damp isn't just an unpleasant decoration; it's a potential health hazard. Research has shown that the spores produced by mould can aggravate asthma and the bacteria they carry can cause infections. This hazard can be worse for vulnerable groups like the elderly, babies, young children and pregnant women
What kind of effects does this have on pregnant women?
There are no studies on the effect of mould in pregnancy. Sometimes I think "and pregnant women" is a phrase that's included in these pronouncements because they just don't know and want to cover themselves. However, if you are susceptible, symptoms can include stuffy nose, rash, eye irritation, and sometimes wheezing or shortness of breath. But they're only really experienced by people with reduced immune systems or chronic respiratory conditions such as asthma.
If you have it in your house, make sure you keep the place as well ventilated as you can (it's not only caused by damp but condensation too) and wash it down with either biological washing powder or white vinegar dissolved in water. Either of these will kill the mould. However, it doesn't get rid of the cause so it's going to be a recurring problem. If you've got or can get a dehumidifier, that can help keep the problem down, especially in the winter when you're going to get more condensation than in the summer, due to central heating.
Hope that helps