I feel led to post this about hormonal birth control while a mother is breastfeeding. Hormonal birth control containing ESTROGEN will most probably decrease a mothers milk supply. It doesn’t happen overnight but it would surely affect a milk supply within a week or two.
The literature all over the internet states that PROGESTERONE only birth control will be safe for the mother and the baby and it should NOT affect a mothers milk supply.
In my 9 years of running Lowcountry Lactation Station I have seen more then a few mother’s milk supply decrease most certainly related to progesterone only birth control. I know this for fact because when the mother stops the birth control and starts to pump and use mothers teas or lactation cookies her milk supply comes back. This is not a guarantee though!
Because birth control is not started until 6 weeks postpartum a reduction in a milk supply can be attributed to a multitude of reasons.
Keep in mind that you can get pregnant while breastfeeding and you can ovulate before you menstruate so you can’t count on your period to let you know you that you are fertile.
Breastfeeding affords you 98% of birth control when you provide 100% of your infants nutrition. If you do get pregnant while you are breastfeeding your breast milk changes back to colostrum when you are 20 weeks pregnant. This can be devastating if you wanted to continue to breast feed your breastfeeding infant longer. You would have to supplement with food or formula to ensure adequate nutrition.