How much say does a to-be father have about what the pregnant mother-to-be does / does not eat?

[Excuse any potential ignorance towards non-1 male/1 female relationships…]

If a woman is pregnant with a man’s child, how much control does he have over what she eats? If she is eating only junk food and greasy meals, do you think he has any authority in having her eat better? Also, if she is not eating foods that have vitamins, minerals, etc., is it acceptable for him to strongly suggest that she eats fruits/vegetables?

I’m fairly certain that the man has no legal authority in this case, but what do you think? It is his baby as well, is it not?