The Birth Control Pill, Fertility and Thin Endometrial Lining

Many women take the birth control pill for periods of time in their lives. Oral contraceptives have many uses in women’s health, ranging from the most obvious ones like contraception to the treatment of hormonal disorders. In some women who have conditions such as PCOS or endometriosis, the birth control pill is often used as a long term treatment option. It is prescribed either to induce menstrual cycles in PCOS, or to quiet and calm down endometriosis tissue and pain.

After working in naturopathic fertility care for over 14 years, I’ve treated many patients going through assisted reproductive technology including IVF, IUI, and Frozen Embryo transfers. Over time, I’ve seen that there are some women whose endometrial linings will not thicken enough to proceed with a transfer. Conventional treatments for this particular problem may include high doses of Estrace, and other therapeutics aimed at increasing blood flow.

Thin lining can happen for a variety of reasons, ranging from low estrogen, to poor blood flow and low nitric oxide. In many cases, thin lining can be successfully treated using Estrace, supplements or medications which increase nitric oxide and blood blow. Acupuncture protocols can also be employed with a generally excellent degree of success. Unfortunately, in some cases, thin linings can be resistant to these therapies. In some of these cases there appears to be a correlation between the long term use of oral contraceptives (birth control pills).

A study conducted in 2012, reviewed the charts of 137 women in a fertility clinic who were undergoing a frozen embryo transfer cycle. During this type of cycle, no follicles (eggs) are retrieved, and a previously frozen embryo is transferred into the uterus. This requires the endometrial lining to be at an optimal thickness, so that the embryo may implant. 30 of the patients in the group of 137 had an endometrial thickness of less than 0.7mm, which is thinner than the minimum requirement to transfer the embryos.

The mean number of years of birth control pill use was 9.8 in the group with the thin lining and 5.8 in the group with normal linings.

When the statistics were analyzed further, it was found that approximately 63% users in the thin lining group had been on oral contraceptives for 10+ years compared with only 28% in the normal lining group.

Interestingly, it appears that this problem could be related to the ratios of the estrogen and progesterone receptors in the lining. In these women it may be that the ratio of estrogen to progesterone receptors may in fact be reduced. This may be similar to the mechanism through which Clomid can result in a thin endometrial lining.

Studies in rats have shown that with long term synthetic progestin use, the number of estrogen receptors in the endometrial lining will decrease. This may occur through the same mechanisms by which the oral contraceptive pill reduces the risk of endometrial cancers.

Another concern is that the regenerative stem cells in the endometrium become less active with the prolonged downregulation from birth control use.

I spoke with Dr. Bob Casper, one of the authors of this study and one of the most prominent Reproductive Endocrinologists in Toronto to ask him about his perspective and clinical experience on this matter.

Dr. Casper has been seeing this correlation between long term oral contraceptive use in patients with resistant thin endometrial lining in his practice and has been working to find a solution for this. He mentioned that using larger doses of Estrace does not help in these particular women and may even reduce the number of estrogen receptors further in the endometrial lining through a process similar to a feedback mechanism. As such he is researching new therapies to restimulate the growth of endometrial lining.

Dr. Casper also mentioned that working in the field of fertility makes these cases more visible, and that there are likely many women who do not have this outcome from using the birth control pill. It is not known why some women develop this problem and others do not. Currently, Dr. Casper and his team are working hard to effect this condition through research. I’m also doing some research on supplements and nutritional modifications to upregulate estrogen receptors and stem cell regeneration in the endometrium. Hopefully there will soon be an effective solution to this clinical challenge.


  1. Oshrit Lebovitz, Raoul Orvieto. Treating patients with “thin” endometrium – an ongoing challenge. Gynecological Endocrinology 2014 30:6, 409-414
  2. Talukdar N, Bentov Y, Chang PT, Esfandiari N, Nazemian Z, Casper RF. Effect of long-term combined oral contraceptive pill use on endometrial thickness. Obstet Gynecol. 2012 Aug;120(2 Pt 1):348-54.

14 thoughts on “The Birth Control Pill, Fertility and Thin Endometrial Lining”

  1. Avatar photo

    Thank you Lara for reading!
    Yes indeed- to Dang Gui in fact and some other herbs with similar mechanisms. However in these cases, it seems very different from menopause, where the tissues would still have the ability to be estrogen responsive. A lot of the research on phytoestrogens is done on tissues that are still estrogen responsive, whereas in this condition, the lining is fully unresponsive to any amount of estradiol. I have a feeling that these might have to be used in an adjunct way. Researchers are talking about possibly pulsing estradiol (or in our case phytoestrogens) – perhaps to sort of trick the cells into responding. I think the most interesting factor is that it seems that the cells themselves don’t grow and the endometrial stem cells which are responsible for the response actually stop replicating after awhile of being shut down. So for that reason I’m looking at different herbs and supplements that might improve the factors involved in the cellular regeneration process in the endometrium. I will definitely let you know once I find out more! :)

  2. Great article Fiona! Have you also noticed this effect after Mirena IUD? I have a two patients with secondary infertility after the Mirena, with very thin linings.

  3. Avatar photo

    Thanks Shawna!

    I haven’t in particular but that is interesting since it secretes progestin. Were their linings responsive to estrogen at all?

    Thanks for sharing…super interesting.

  4. I was on the depo shot for almost 5 years before they told me that I should have been off of 2 to 3 years tops now I have pcos its been 7 years and I still can not get pregnant and I still don’t have regular periods… Before the depo I had normal regular periods now I get them 2 times a year if that…

  5. Great article !!! I was put on birth control when I was 15 1997 to regulate my periods and didn’t get off the pill till I was 2008 . Dr told me as soon as I came off the pill everything should be back to normal within a month . It took me 4 years to get pregnant and just this past two years I have became normal . I am soo glad that you did this article .

  6. I was on birth control for nearly 15 years. I stopped taking the pill in July of 2013. My periods were noticeably lighter after BC compared to before BC. I’ve been ovulating normally but my lining actually shrinks from cd 13(6.8) to cd 16(6.3)even though my egg has greatly increased in size. This occurred both cycles that I was monitored. Have you seen this before? Any treatment suggestions would be wonderful! Thank you.

  7. HI Kathleen,

    yes this may be related to the phenomenon described above. The treatments appear to be 1) improving circulation to the lining and 2) improving/upregulating lining cellular health. Supplements that increase nitric oxide have been helpful in some women – more research is needed!

  8. Dreaming of Diapers

    Dr. Fiona, have you been able to find any herbs/supplements that upregulate estrogen receptors and stem cell regeneration in the endometrium yet? I am part of this “Chronically Thin Endometrium” group and they are telling me my only option is gestational carrier and that is not a possibility right now. If you have any suggestions, they would be greatly appreciated. Thank you!

  9. Stephanie Moratelli

    Hi, I have a question I’m hoping you can give me some insight with. I have pcos and have never had normal periods usually having only one big heavy long period per year. My RE put me on bc (Vestura which is I believe generic for yaz) specifically to block some testosterone I believe and help me get pregnant eventually and also help me lose some weight. This was one year ago I started the bc and my periods were so regular I could tell you what time they would come. I felt super normal, not crazy, and actually lost about 35 lbs over the course of a year with no change to diet or exercise. But about 3 or 4 months ago my periods were basically non existent. They would come on the exact day or 1 or 2 days late but they were basically only dark brown or super light spotting for about 2 days. My gyno said she thinks because it was exactly on time that it’s my period but because of being on the bc for a year my lining is so thin that it doesn’t have much to shed each month. I stopped my birth control this month to try to get pregnant. She gave me the go ahead to start trying but I’ve been reading up online and am nervous that my lining would be too thin and I might miscarry because of that. Should I wait to try? It’s my understanding according to my RE that I only have a couple months after coming off birth control to get pregnant otherwise I will most likely need further assistance because my cycle will go back to what it was before which is basically non existent. Thanks in advance for your help !

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