Hi.. Breast feeding itself can cause inhibition on the menstruation cycle, a condition known as lactational ammenorrhea.. They can last as long as you are breast feeding.. But this is not completely reliable.. Hence you may use the birth control pill.. Hormonal pills can be safely used after 6 weeks following delivery.. Use of combined pills (that contain estrogen and progesterone) can suppress milk secretions too.. You may have to consider this effects too.. Well it is better you use progesterone only pills, also known as minipills for the time being (if you are on combined pills) for they do not hamper milk secretions.. Talk to your doctor if needed..