Context: This 孕妇营养餐 seems to be a special meal custom-designed by nutritionists. It's meant to be eaten by pregnant women. So how would you translate it into English? Pregnancy nutrition meal? Nutrition meal for pregnant women?
I would say Nutritional Meal for Pregnant Women/ Nutrition meal for pregnant women is more accurate than the first if you were to describe it better, but pregnancy nutrition meal is more accurate if you were to directly translate it from Chinese to English. 孕妇营养餐- yunfu (pregnancy) yin yang can (nutrition meal)
If you are using it in first person, “pregnancy nutrition meal” sounds more “normal” to English speakers (for example: this is my pregnancy nutrition meal”. “Nutrition/nutritional meal for pregnant women” doesn’t have a very nice flow to it when you are speaking with someone so if you wanna use that phase, you can replace “pregnant women” with “pregnancy” instead. (Example: this is your nutritional meal/diet plan during/for your pregnancy.)
If you google "pregnancy meal" or "pregnancy diet" you will get a lot of hits. Or word it as meals to eat during pregnancy or something like that. I don't think you need to worry about the "nutritional" part of the Chinese term; that's implied in "pregnancy meal". No one is going to think it's junk food to eat when pregnant.