Fertility While Breastfeeding


My husband and I practiced NFP to avoid pregnancy for the first months of our marriage and then used it to conceive. The first time we tried, we were blessed with a baby. Unfortunately, I miscarried the baby at 4 weeks, 3 days. The next time we tried, we conceived again and I was put on progesterone. Our baby boy was born fine and healthy in October, 2007.
I chose to exclusively breastfeed my son. When my son was four months old, I got my first period. Mind you, I was breastfeeding him 8-12 times a day still and he never slept for more than four hours straight through the night until he was about six months old and even then it was five to six hours straight, tops. I was thrilled, though. I would have loved to have another baby. But no such luck.

My son is now tem months old and I have had five cycles and still no pregnancy. What’s more, the first cycle had a luteal phase of about four days, the second about the same, and then it crept upwards and it is now about eight or nine days (isn’t this still too low?). What could possilbly be going on with me? Why would my period return so quickly if I’m not even fertile? Am I possibly conceiving and miscarrying each cycle?

Also, when I was six months post-partum and just starting my son on solid foods (literally, that week), they ran some blood tests on me and found that my prolactin level was 16.73 ng/mL. Isn’t that normal for a NON–breastfeeding mom? I thought that my levels were supposed to be around 50-70. Only within the last two weeks (son at nine months of age) has my breastfeeding sessions ever fallen below six times per day.

I have no idea if it is related, but my FSH was 2.1 mIU/mL and my LH was 4.5 mIU/mL. Isn’t the FSH supposed to be greater than the LH? I read that somewhere on your site but I have no idea if it’s not true for breastfeeding moms.

Should I be concerned that something is wrong with me?

Thank you,



Last Updated: January 30, 2022
Dear Amberly,

Even with exclusive breastfeeding, some mothers find their periods returning early. The first few periods may not be fertile if the mother continues with total breastfeeding, as you have done, but we do assume fertility once any bleeding occurs and recommend charting. Since your luteal phases were short and gradually lengthening we would guess you probably were not fertile at first, but may be by now.

As for your lab reports, we don’t know the ranges for the hormones that were tested and would advise discussing this further with your doctor. You can also seek a second opinion from an NFP-knowledgable doctor.

Andrea and Ron Gronsky

Answered By:

Andrea and Ron Gronsky
Andrea and Ron Gronsky, PhD, Professional Members of CANFP,now retired, taught the Sympto Thermal Method through the Couple to Couple League, in the Oakland Region.

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