Melatonin pregnancy developmental delays?

When I was pregnant my Obgyn gave me the ok to take melatonin during my pregnancy. I felt like melatonin was ok because it occurs in the body naturally. I recently came across some research that it can cause developmental delays if used in pregnancy and it has made me worry a bit. My dd is 7 months and doesn't babble dadada yet or roll from back to front. All she does is sit up. Am I just over worrying? I feel guilty now...