How can ketchup be a problem during pregnancy? Although perfectly safe to eat during pregnancy, Ketchup (also known as catsup in some countries) can aggravate gastrointestinal symptoms such as heartburn or reflux due to the high level of acidity. Commercial ketchup often has high amounts of sugar. Some women tend to have more aggravated symptoms of heartburn or acidity during pregnancy, therefore it is better to consume in moderation.