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My question is this and im going to use actual confirmed dates for absolute peace of mind for both parties involved. Let me start with a confirmed date of a womens last menstration on febuary 23 (her period), so if on august 4th she is told shes 20 weeks this does not mean her date of conception would have been feb.23, but rather suggest conception in the approximate time zone of feb23-mar.23 correct?? Please help us put this to rest! No one seems to be able to answer this question and stand behind theyre answer. Thank you very much for your time.

Hello Ben from Canada,

Of course the actual date of conception cannot be known but it is generally in the 2nd week since we measure gestational age from the 1st day of the last menstrual period.  Therefore, if she is 20 weeks gestation on August 4th, then conception occurred 18 weeks ago (around April 7th) since her LMP would have been 2 weeks prior.

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


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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, Society of Assisted Reproductive Technology, American Association of Gynecologic Laparoscopists, Fellow of The American College of Obstetricians & Gynecologists,Resolve-National Chapter, Open Path - Northern California, Board of Directors Monterey Medical Society

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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