Can eating corn starch make your baby big?

Depends: Corn starch is a carbohydrate. Eating too many carbohydrate can make a person gain weight. I'm not sure what you mean by "make your baby big". Are you talking about weight, height or something else. Corn starch is present in a lot of edible items we eat every day. The amount eaten has to be considered. I would advise you to talk to your pediatrician & a dietician.

No effect : Unless you just eat all starches, meaning carbohydrates and gain a lot of weight or have gestational diabetes it should have no effect on your babies weight. It may cause you problems with your health ad weight.