When you find yourself gaining too much weight? There are approximately 1,000 calories in one entire durian fruit, so that's half of an adult's calorific needs.
For a pregnant woman, it might result in an overweight foetus. Remember, everything in moderation.
Even too much water might kill you.
http://sg.theasianparent.com/pregnancy_diet_donts/
http://www.hpb.gov.sg/HOPPortal/health-article/3826