Infertility/Fertility/Short Luteal Phase
I ovulate on day 24 of a 28 to 31 day cycle, and have been trying to conceive for 18 months; I believe I may have had a miscarriage during this time but cannot be sure. My GP referred me to a Consultant Gynaecologist who prescribed Levothyroxine 50mcg per day 6 weeks ago following a blood test which showed my TSH level was 3.21mU/L which I understand is within normal range; however I have been advised that it may optimise reproductive outcome if my TSH level is maintained at <2.5mU/L. My Progesterone level is normal and following a scan my reproductive system looked healthy. I have mentioned my short luteal phase however it was not a cause for concern to either my GP or the Specialist I visited however everything I have read indicates that a luteal phase of less than 10 days can pose problems. I would be grateful for any help. Thank you.
Hello Caroline from the UK,
If you are detecting and verifying the point of ovulation, and the luteal phase is only 4-7 days long then certainly that is a problem. However, it is very unusual to have a luteal phase that short. If ovulation occurred, the luteal phase is almost always 14 days long. The term "luteal phase defect" does not mean that the luteal phase is too short, it means that the endometrium did not develop appropriately. It is diagnosed by an end cycle endometrial biopsy for development. If the luteal phase is not 14 days, the problem is that the endometrium will not be developed correctly for implantation to occur AND it won't have the proper hormonal support to sustain a pregnancy. In most cases where the cycle is short, that is an indication of an ovulatory dysfunction and so proper hormonal production is incorrect leading to an abnormal cycle or bleed. Treatment for luteal phase defect is done by progesterone supplementation after ovulation or if there is an ovulatory defect, then by ovulation induction by fertility drugs.
Keep in mind that there is no certain way to detect ovulation. Ovulation predictor kits (OPK) only indicate that an LH surge has occurred which is the prerequisite for ovulation, but not that the egg was released. Ultrasound can also detect that there is a follicle present that is ready to ovulate, but not when it ovulates. By doing a follow up ultrasound over the next two days, one can then say that ovulation occurred in the interim. So one question I would have is in fact you are ovulating on the 24th day, which is very late in your cycle, and if it fact you did ovulation this late, the cycle should be 38 days long because once ovulation occurs, the luteal phase is almost always 14 days. My suspicion is that you have an ovulatory dysfunction or are not detecting ovulation correctly.
My recommendation is that since you have now seen two Physicians who are not expert or knowledgeable in reproduction/infertility, it is time for you to see a reproductive specialist to help you achieve a pregnancy.
In terms of TSH, for reproductive purposes, it is recommended that the TSH level be less than 2.
Dr. Edward J. Ramirez, M.D., FACOG
Executive Medical Director
The Fertility and Gynecology Center
Monterey Bay IVF Program
Monterey, California, U.S.A.
for additional information check out my blog at http://womenshealthandfertility.blogspot.com
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