I am ebfing my 1 year old, can this cause missed and irregular periods?

Yes: I assume you meant 'breast feeding'..Certainly this can cause irregular or absent periods.

Yes: When you are breast-feeding, there is a hormone called prolactin that is elevated. This hormone interferes with your normal cycle and causes absent or irregular periods. I hope that this answers your question!

Yes: Breast feeding can cause irregular periods for some women. The less frequently a woman is breast feeding the more likely her hormones will go back to normal and periods will become regular. When a woman is no longer nursing the periods should be regular. If they aren't then get checked.