Does having a baby make you more fertile?

No: If you get pregnant, you are fertile. Stress, though, can effect ovulation and therefore fertility. It's not uncommon for women who have trouble conceiving the first time get pregnant again without difficulty, probably related to less stress.

No, with exceptions.: Having been pregnant doesn't necessarily make one more fertile. It does prove one thing however and that is that one has been successful in becoming pregnant and that is important. One exception would be a woman who has endometriosis; if she has become pregnant and carried a pregnancy to term her condition may improve to some degree making her more likely to become pregnant in the future.