There is absolutely no behavior too low for censure from online trolls. Taking the complaint at face value, some guy on a bike ran into a pregnant woman. Maybe you honestly do not know what response would be appropriate in this circumstance -- that would be to stop, apologize profusely, find out whether or not the woman is OK, get help if necessary. This response is also expected even if you hit a man or a child or a dog or a cat or any living thing with your bike. I know that it seems like a LOT of trouble, SO AVOID HITTING PEOPLE WITH YOUR BIKE.