Ovulating while breastfeeding

A friend of a friend recently asked me a question that I couldn’t answer. She is in her late 30s, has a two year old daughter, and has been breastfeeding on demand for the past two years. She and her husband have been trying to have another child, but she just recently learned that she miscarried after their first attempt. She has only recently started getting her period again, and was wondering if the breastfeeding could negatively impact her body’s ability to get pregnant again. I speculated that the high levels of prolactin which occur during breastfeeding might inhibit ovulation, just as high levels of estrogen inhibit breastmilk supply by competing with prolactin for binding sites in breast tissue, but I told her I wasn’t really sure and that I would investigate. I thought that somehow estrogen and prolactin were counter opposites: one could not exist in high levels while the other was around. Turns out I was waaaaay off base. Here’s what I found:

During pregnancy, the corpus luteum, acting on instructions from the placenta, secretes the estrogen and progesterone necessary to maintain the pregnancy. These high levels of steroid hormones simultaneously supress Follicle Stimulating Hormone (FSH) and Leutenizing Hormone (LH), the two hormones most responsible for ripening an egg and then triggering ovulation—after all, if you’re already pregnant, there’s no need to ovulate. After delivery, once the placenta is removed, the high levels of estrogen and progesterone no longer exist, and the levels of FSH and LH gradually begin to rise again, preparing the body for ovulation. Eventually, as the levels creep up, the pituitary takes notice again, and begins to release more FSH and LH through a negative feedback loop, which eventually will trigger ovulation.

“Most nonlactating women resume menses within 4 to 6 weeks of delivery, but about one-third of the first cycles are anovulatory, and a high proportion of first ovulatory cycles have a deficient corpus luteum that secretes sub-normal amounts of steroids. In the second and third menstural cycles, 15% are anovulatory and 25% of ovulatory cycles have luteal-phase defects…Lactation, or breastfeeding, further extends the period of infertility and despresses ovarian function. Plasma levels of FSH return to normal follicular phase values by 4 to 8 weeks postpartum in breastfeeding women. In contrast, pulsatile LH stimulation is depressed…in the majority of lactating women throughout most of the period of lactational amenorrhea.” [1]

In other words, after not menstruating for so many months, it takes the body a few tries to get the delicate hormone balance back up to speed again. The first few cycles either don’t release an egg, or if an egg is released, the corpus luteum, which is responsible for secreting enough progesterone to maintain the pregnancy until the placenta can take over, isn’t quite up to the task. This is called a luteal phase defect, and it’s a very common cause of early miscarriages. In women who are breastfeeding, the process of returning to normal ovarian cycles takes even longer.

In breastfeeding women, FSH, the hormone responsible for ripening an egg, returns to normal pre-pregnancy values fairly early, but LH, the hormone responsible for triggering egg release, continues to be surpressed due to the breastfeeding. (However, contrary to popular belief, prolactin is not at all responsible for this supression. It’s the constant suckling and stimulation of the nipple itself which actually suppresses ovarian function, which is why on demand breastfeeding is so essential to maintaining lactational amenorrhea.)

So, there you have it. To answer the question: it will probably just take a few more cycles for your body to get back into full swing in terms of ovulating, but continued breastfeeding did not contribute or cause the miscarriage in any way, and will not prevent conception. Most likely, the miscarriage was caused by a short luteal phase or corpus luteum that just wasn’t quite ready to maintain a pregnancy, and this will no longer be a problem once your body goes through a few more cycles and gets used to ovulating again.

[1] Hatcher, R.A. et. al. (2004) Contraceptive Technology, 18th Revised Edition. Ardent Media, Inc.: New York.

This entry was posted in Breastfeeding, Fertility and Conception, Menstruation, Miscarriage, Questions. Bookmark the permalink. Trackbacks are closed, but you can post a comment.


  1. TinaH
    Posted March 7, 2006 at 8:46 am | Permalink

    It was a glorious 14 months after the birth of my baby boy that “Aunt Flo,” as menstruation is called among the women in my family, took a hiatus. I’d forgotten what it feels like! Took it a while to get regular again, too.

  2. k
    Posted March 7, 2006 at 11:35 am | Permalink

    Toni Weschlers (sp?) book Taking Charge of Your Fertility was absolutely worth the money. It was a great resource after my miscarriage. My cycle went into complete chaos. I still haven’t got the hang of charting while breastfeeding… She has an entire chapter on it, but something about getting those four continuous hours of sleep before taking your temp in the morning. Yeah, not happening so often here. Thanks for writing on the fact that nursing does not “cause” miscarriage. Hope your friend is doing well. I wish her lots of baby dust =)

  3. The Student
    Posted March 8, 2006 at 9:48 pm | Permalink

    I *love* Toni’s book. I’ve been reading it slowly, off and on since January, and it’s amazing! It’s so informative, and breaks down the cycle so simply and thoroughly. *Definitely* worth the money, indeed.


  4. laura@dierks.org
    Posted March 22, 2006 at 10:29 am | Permalink

    Thanks for the info and the research. I’m glad to know that it wasn’t the breastfeeding that directly caused the miscarriage and that it seems like it’s part of the natural “getting back up to speed” cycle of things. It makes me feel better about letting my daughter continue to nurse as well. I had considered weaning her, but I think it seems fine to let her continue. Thanks again!

  5. MilkyMama07
    Posted July 7, 2008 at 10:43 pm | Permalink

    This is great information! I’ve been doing BBT charting and last cycle, I had only a 5 day luteal phase. My dd is still nursing at 18 months. I’m glad though to note that I’m O’ing, and hopefully things will get back to “normal” soon!

  6. 3boysJaney
    Posted March 13, 2009 at 2:19 pm | Permalink

    Hello – very interesting reading. What about the stimulation of the nipple during breast-feeding releasing oxytocin, causing tensions within the uterus? I have 3 healthy young boys but have had 2 previous miscarriages whilst breast-feeding. I am now pregnant again after 2 irregular periods and one regular- only 5 weeks and am still happily nursing my little 17 month old but am aware of low grade tensions retro-pubically during our longer nursing sessions – all very reminiscient of my previous losses. I really want to carry on nursing him but am still suspicious of the tensions. Any thoughts? Thanks.P.S. I am secretly terrified of the thought of a 4th baby but would like to have my cake and eat it if possible-certainly willing to give it a shot.

  7. MamaD
    Posted March 16, 2009 at 7:47 am | Permalink

    My period returned when my nusing daughter was 9mths and I concieved 7mths later but miscarried. Shortly after that I began charting and found I have a short luteal phase. My daughter is now 31mths and still nursing, albeit only between 6pm and 8am, but I still cannot concieve because of a short LP. I think I am going to have to wait until she fully weans before my body will allow me to concieve again. Luckily I always planned to breastfeed upto age 3 so that isn’t too far off now!

  8. Rosalee Hamilton
    Posted April 7, 2012 at 12:14 am | Permalink

    I have a question, I have been breastfeeding my daughter on demand since birth and she is now one. My husband and I have been TTC for 4 months ( I got my period back six months ago) and so far all of my cycles have been anovulatory but very consistent. I am young (mid 20’s) but now I am beginning to get concerned. I had planned on having my kids 18 months apart but that deadline passed sometime ago. Now we’re pushing 2 years apart and still no eggs. I am wondering what i can do short of stopping breastfeeding my daughter altogether (i want to continue till she is at least 2 and would like to tandem nurse) is there someway to get my cycles to be ovulatory instead of empty and eggless? or even worse, is my pattern of anovulatory consistent cycles a sign of secondary infertility? help please!

  9. Mariah Grafel
    Posted April 10, 2013 at 5:05 pm | Permalink

    I also have the same problem as Rosalee but have just completely weaning my 14 month old will my fertility come back?

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