Reality isn’t always obvious. Pregnant people of all lifestyles listen to opinions, doctors, media, and do the best they can with the information they have. The mainstream opinion has been that diet sodas are healthier than high sugar sodas, and there was no reason to think it would lead to poor health outcomes for mother or child.

People who drank regular sodas daily probably thought switching to diet soda would be the healthier option, and may have switched as a way to keep their routine while staying a little healthier. Nobody told them this was a bad idea, because nobody new it was a bad idea.

This type of comment is blaming the victim for not having information that didn’t exist.