what kind of company would fire a pregnant woman ? you might be suspended from near future promotion or project but the nation law won't allow a woman to get fired because of getting pregnant. I would inform the boss after the safe first trimester period especially if you have morning sickness, it should be more obvious and also when you post in socmed, your colleague might find out. Everyone's pregnancy is also different , some has it easy and it does could interfere with the work BUT it's something unavoidable to inform the company sooner or later