Kata
I had dengue last year, so when I got pregnant then got bitten in Indonesia (Jakarta) I was a bit worried. I asked my gynae who said malaria (dengue too) are dangerous in that you get a fever and the raised temperature can damage your baby's nervous system.
She then reassured me of the likelihood of contracting malaria. Without wishing to underestimate a serious condition, as long as you are staying to Singapore and are careful you should be OK. There are some great products available against mozzies, and one of the best I have found is a Johnson's baby product like a toner water which is against mozzies. Not very strong so you would need to reapply.
Also, try sun creams with mozzie repellent in them, eat garlic or Marmite/vegemite (old wives' tale but it seems to work!), and burn coils near you. You are fine in sgp, just avoid beaches and vegetation areas at dusk.
It's about being sensible, and taking care over everyday things that you will do with other aspects of being pregnant. I have only been bitten 3x in 18 months and I do go to the jungle/swampy/out of the way places where malaria and dengue thrive.
