gynae will usually prescribe prenatal vitamins. yes it's true that these vitamins can come from food but i believe you'll then need to ask gynae how much of food should be taken to ensure you've all the required nutrients and minerals for you to conceive again, probably draw out a meal intake plan?
gynae usually ask moms to take fish oil which will make the unborn baby smarter, etc. There are various other reasons that may make the baby unhealthy not just bcos not taking pre-natal. I guess your gynae will be in a good position to inform & advise what to take & help you in your conception journey.