I agree that you should stay away from malarial areas while pregnant, but if you must go it is possible to avoid getting malaria without taking drugs. I spent many years in total in malarial areas, some with my wife and young sons. None of us or those who visited us got malaria. Precautions we took included daily (just before dusk at the latest) closing of all windows and doors and spraying all ceilings-to-wall corners, around windows and doors and under furniture with reliable insecticide (original Baygon was our preferred one). If we went out anywhere at or after dusk we wore Mosquito Milk (check Boots, tropical strength was what we preferred) all round the hairline, behind ears, on neck and all exposed skin elsewhere (underside as well as upper of arms to fingertips, ankles, legs and feet unless covered with clothing). Incidentally, none of the pills are 100% guaranteed to prevent malaria nor are they 100% safe or side-effect free. My mother-in-law arrived having taken them on her doctor's orders but felt so unwell that she stopped taking them. She did not get malaria either.