Breastfeeding Community
1.66k Members
287246 tn?1318570063


Hi ladies!  I wanted to post this (I know it is long but super informative), because this question often gets asked.  I have tried to explain to people about the fact that some women can get pregnant while they are nursing and others can't.  I just thought this was great information to pass along to this community.  Anyway, this was written by Katherine A. Dettwyler, Ph.D, in 1995, but is still great information.  Hope this helps someone!

There is a chapter in Breastfeeding: Biocultural Perspectives on "Breastfeeding, Fertility and Maternal Conditon," by Peter Ellison. He is an anthropologist and head of the anthropology department at Harvard University. This chapter takes a historical look at the research that has been done on understanding the links between breastfeeding and fertility, from the earliest days up to 1993, when he finished his chapter (it takes forever to get a manuscript through all the stages in to print).

Here's my brief synopsis of his thorough chapter. Suckling by the baby causes the mother's pituitary to release prolactin. It used to be thought that prolactin directly affected ovulation/fertility, but new research suggests that there is another hormone intermediate between prolactin and the ovaries. So that high levels of prolactin lead to either high or low levels of this other factor, which then affects fertility. Fertility is not an "either/or" sort of phenomenon. Post-partum, a woman does not ovulation for a while, even if she isn't breastfeeding. If she is breastfeeding frequently enough to keep her prolactin levels above her individual critical threshhold for fertility (and women vary in this threshhold) then her fertility is suppressed.

The greatest level of suppression is not ovulating, but as your prolactin levels go up, your fertility will gradually return. First you will ovulate, but not have the proper hormone levels for fertilization; then you will ovulate and fertilization may occur, but you still may not have the proper hormone levels for implantation; finally, you may ovulate, be fertilized, and implant, but not have the proper hormone levels for continuing the pregnancy, so you have a very early miscarriage, probably along the lines of minutes or hours after implantation, so you wouldn't know you had been pregnant. It is also possible to ovulate without having the right hormonal levels in the right combinations for the uterus to have been preparing for implantation, so yes, it is possible to ovulate without menstruating. For all of these stages, there seems to be incredible individual variation between women. Some women get pregnant again the first time they ovulate, with no intervening menstrual periods. I knew a woman in Indiana years ago who had three children in six years with no menstrual periods! Her doctor couldn't figure out when to predict her due date :)

Also, would you believe there is no research out there yet, none at all, on whether it is possible for the trajectory of gradually returning fertility to be reversed as a result of increased nursing? I specifically asked Peter Ellison to include this research in his chapter, and he assures me there isn't any, though as he puts it "Logically, it makes sense." That is, if the baby nurses more frequently again,, after the mother's periods have returned, it would raise the mother's circulating levels of prolactin, presumably high enough to affect fertility again.

I am sure that this works, both from personal experience and from anecdotal reports from other nursing moms. To give a specific example, with my third child Alexander, I worked mainly from home the first year of his life, and spent many hours at my computer writing with me logged on and him latched on! The summer of 1992, when he was a year old, I was at home for the summer (not teaching classes) and he nursed a lot. When he was 13 months old, and fall semester was starting, I put him in day care 6 hours a day, so I could have more time at the office, and my periods promptly returned the next month. I had a period in October, and one in November, then we finished for the semester in mid-December and I was at home with him all day for 5 weeks (what a job :)). I didn't have a period in December or January, then resumed again for good in February. Sigh. I wish someone would develop a pill that mimicked the actions of lactation amenorrhea so I didn't have to have periods for the next who knows how many years. And I don't have PMS or menstrual cramps or anything, so I know I shouldn't complain. Back to the subject at hand -- my understanding is that a woman is born with thousands of eggs, and that menopause has nothing to do with using up all your eggs.

I would imagine that there could be some connection between continued breastfeeding and failure to sustain a pregnancy, especially in a woman who released large amounts of prolactin in response to nursing, or whose ovaries were especially susceptible to whatever level of prolactin (or other hormone) she did produce. You should consult a reproductive endocrinologist to see if this is the case. I don't think the oxytocin levels that cause uterine contractions could be leading to miscarriages that long after the birth of the first child, but the prolactin levels might be interfering with implantation or continuation of the pregnancy.

You can find much of Peter Ellison's information in his already published works. If you have access to a university library, look him up on the computer and see what they have by him. I hope this helps.
5 Responses
906115 tn?1344200509
I have had 5 babies, I breastfed exclusivly with all of them but the 4th as she died shortly after birth,

I got pregnant with my second when my first was 6 months but I had MC the month before also, I got pregnatn with the third when the second was 9 months old and the 4th when the third was a year old. My periods returned like clock work at 6 weeks post partum wiht all of them! I also tandem BF my second and third whole preggers with the fourth! Yep still got pregnant! I had 4 babies in a 3 year span, yes they were all premature! Due to low progesterone levels. I lactated for 2 years after I stopped nursing my 3rd.

Now on to my 5th, is now 6 months and my periods hav enot returned, I have bled 3 times but no PMS or cramps and just not Oing, not even sure if they were periods as they were 6-7 weeks apart. First time I have not had regular cycles! So I hve not gotten pregnant yet either. I took progesterone with my pregnancy this last time to keep him in ther full term. Progesterone is the hormone that will decrese with nursing to not let a baby implant right? You will not O if it is too low and will mc if it is too low. Also your milk will dry up some from progesterone if you are Oing, so that is a good indicator you are Oing too. It also goes up with pregnancy so some woman their milk will dry up if they get pregnant. I had an over supply so mine did not.

Does the book or study talk about progesterone?????

I was told to stop nursing or I would mc so I did with my first after mc. But I regreted it! He was 9 months old:( I refused to with the others and it did nothing as far as contractions which was what I was told was the only concern, I was not told about hormones then, but hey if they tested them back then  97,98,00,01 then I would of not had pre term babies either!

My low progeterone is not related to my BF, I had to be on suppliments to get pregnant and nothing interfere wiht implantation this last time till 32 weeks gestation.

I noticed that as soon as my babies slept mroe through the night is when I would O and get pregnant right away each time. It had nothing to do with day time feedings or feeding baby foods just the night time feeds, I am still feeding this one every 1-2 hours during the day and night so far and who knows when that will stop;)

thanks for the info!!!

287246 tn?1318570063
Wow girl!!!  You have been super busy :)

Well, I have 6 and have never had any problems getting pregnant.  Since I am still nursing, I think I am one that falls into this category of just not being able to get pregnant while nursing, due to the lower hormone levels.  I have never had to take progesterone to sustain a pregnancy though.

I wanted to post this because so many people are misinformed about fertility during  breastfeeding.  Many think you CAN'T get pregnant while you are nursing.  Others think you can.  But actually neither is true for every woman.  And that's why I wanted to post this.  It is important for women to just know and understand that we are all unique and that just because your friend got pregnant while nursing doesn't mean that you will or just because your friend couldn't get pregnant while nursing doesn't mean that you can't.  Hopefully I am making sense here.  Ha ha!!

As for progesterone.....I copied and pasted this.  The last paragraph says where you can get more information.  I just thought it was interesting reading and many people ask this question.  But I think it does affect progesterone levels because I chart my temps.  Well before I got pregnant the last time I also charted and my temps are lower post ovulation now (while nursing), than they were post ovulation when I was not nursing.  You still see the temp shift but my temps post ovulation are still lower.  And the reason for that temp shift after ovulation is because of progesterone levels that get higher after we ovulate, in case we are pregnant.
906115 tn?1344200509
yeah that is how I learned I had low progesterone, charting per RE request after my tubal reversal.

SO with mine I have a slow rise after O, this is prior to pregnancy not BF, anyway it si a slow rise then drops down before and I did not have a 14 day luteal phase but mor elike 10 so there was not enough time for baby to even implant good befoer the estrogen levels started coming to shed the uterine linnning.

SO 2 questions for you I will spell out
1. you say it is a lower temp that you are nursing so "Is it just low or do you ahve a slow rise with it also"?

2. Does it still last as long, the full 14 days or is it shorter?

I can not wait to temp but do not get 4 hours of straight sleep let alone 2 yet, haha

WHen did you start temping after pregnancy? and Has your little one not sleeping through the night affected yoru temping?

Sorry I am a bundle of questions, I never knew about what really happens with my body till I went to chart my temps after my reversal and I have not done it nursing yet and never knew anyone to talk to that has.

Yeah great info!!! That is one of the myths or old wives tales we teach at my breastfeeding group, it is amazing the things people think and have been told!

My all time favoriate is "EW NO I can't nurse I don't like drinking milk" hahaha

she actually though she had to drink milk to make milk! I guess I grew up around nursing moms so I knew but people who don't really have lots of myths foating around thier heads and some of them are to darn funny, I know I shouldn't laugh, which I did not at her when she said it but I did later. OH and she was sooo releived to hear she did not have to drink milk!
287246 tn?1318570063
I want to say, first, that I am so sorry that I am just getting back to you.  I have been on MH but only briefly and I knew it would take a little time to answer your questions.

2nd, I would like to say that I am so sorry for the loss you suffered w/ your baby.  I can only imagine what kind of pain that is to endure.  I am so, so sorry :(

Question #1 - I don't have a slow rise, but my post O temps are just lower than what they were when I charted and was not nursing.  I have a def shift so I know I am Oing, but again my temps are just lower.

My LP phase is about the same.  Mine before was like 14-15 days.  Now it is about 13 days, but should still be enough time for implantation to occur.    So not a big change in that.

As far as consecutive sleep.....I would go ahead and start temping anyway.  I never know how my nights will go either, but I have learned that w/ MY body, the sleep or lack thereof, does not seem to affect me personally.  Everyone is different, but for me, it does not affect my temps.  I would say that if you can sleep a couple of hours, or even just 1 hour before you take your temp, you may be good.  It would be a good experiment for you :)

Please let me know if you have anymore questions!  I love helping others.  Honestly, that is the reason why I get on MH mostly.  I would love to be able to volunteer at a Pregnancy Help Center, but just can't "commit".  I stay home and homeschool my kids.  Plus my husband works to unpredictable of a schedule.  So I get on here on my own time table.
906115 tn?1344200509
I hear you about wanting to volenteer somewhere! I am goign to be a LLL soon hopefully, I was asked to but yet to have made the call,lol

Great then I will start temping! At least I will feel like I am doing something;)

It will be interesting to see if my progesterone is the same as before pregnancy! I was told it can change with each pregnancy and that my levels might stay up more after pregnancy for a while.

Yeah thanks, she was pretty and I wish they would of tested the progesterone back then, they only did it after ahving 3 premature babies but for soem reason I was never tested and she was #4! They have known about the progesterone since the 70's I hear. It has been such a blessing to have my little guy here now after all that! He is just my "lovie":)

I will let you know if I have questions too:) I will temp in the morning, I am mid cycles but I maybe can tell if I did O this month as my temps were like clock work after the meds and well before too just bad clock work for ttc.

Top Babies Answerers
287071 tn?1365192513
St. Paul, MN
Learn About Top Answerers
Popular Resources
Approaching your due date? Look for these signs of labor.
Fearing autism, many parents aren't vaccinating their kids. Can doctors reverse this dangerous trend?
Learn which over-the-counter medicines are safe for you and your baby
Your guide to safely exercising throughout your 40 weeks.
What to expect in your growing baby
Learn which foods aren't safe to eat when you're eating for two.