Infertility/Fertility/HCG Trigger Question


I'll give you a little history before I ask my question. My husband and I are trying to conceive our third child, we currently have an 8 and 3 year old. We have been trying for our third for 15 months, I also have a history of mild Endometrisois which has been treated laparoscopically twice. I conceived both my children naturally with no assistance. Here is my question: how long does a 10,000 iu HCG trigger stay in your system? I also took Letrozole days 3-7 and had two nice mature follicles. Any info is appreciated! Thank you for your time :)

Hello Laura from Canada,

Injected HCG will last in the system for about 72 hours but the peak will be around 36 hours.  HCG is an LH mimic, and LH is the body's natural "trigger" for ovulation.  Ovulation is predictable down to the second, hour or day but the range is 24-56 hours.  That is, ovulation will occur somewhere within that period of time.  There is no technology available currently to detect ovulation.  OPK's only detect the LH surge, and of course, they are invalid of HCG is injected.

Good Luck,

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 check me out on twitter with me at @montereybayivf and facebook @montereybayivf.  Skype and internet comprehensive consultations now available via my website for those who want a more extensive evaluation that this site can accommodate.  I also now provide an Email Concierge Advisory Service with a 1 year subscription for patients that want easy access to me to answer questions along their journey (women's health, infertility, pregnancy).  Contact me at if you are interested in continuous access to me.  


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Edward Joseph Ramirez, MD, FACOG


I am a specialist in infertility and advanced gynecological care. I can answer questions about infertility, gynecology related ills, menopause...virtually anything that affects women's health. PLEASE tell me where you are writing from as I am always interested.


I have been practicing as an Ob/Gyn and Infertility Specialist for over 23 years. Gynecology, advanced laparoscopic surgery, basic infertility, IUI's, IVF, reproductive surgery, and ovulation induction are all areas of my expertise. I am Board Certified. I have been doing In Vitro Fertilization in my clinic for 19 years.

American College of OB/GYN, American Board of Obstetrics and Gynecology, American Society of Reproductive Medicine, California Medical Association, American Association of Gynecologic Laparoscopists, Fellow of The American College of Obstetricians & Gynecologists

American Journal of Obstetrics and Gynecology, Wall Street Journal, Monterey Herald, SERMO, Women's Health and Fertility Blog

Medical Degree from Stanford University, Residency at Tripler Army Medical Center, Reproductive Training at Pacific Fertility Center, San Francisco

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