Ask The Doctor > Questions & Answers > I have a pregnancy timing question The first day of my last period.

I have a pregnancy timing question The first day of my last period.

Patient: I have a pregnancy timing question. The first day of my last period was January 30. I normally have a regular 28-29 day cycle. I unexpectedly had intermenstrual bleeding (heavy) from Feb 16-19. I slept with man #1 on Feb 21 and Feb 27.I slept with man #2 on March 5 – he pulled out and I took Plan B 48 hours after (March 7). I had negative pregnancy tests on February 25 and March 7. I had a positive home pregnancy test on March 17 and a blood hcg of 444. I had another blood draw on March 21 and my hcg was 3955.Understanding that it will be hard to *definitively* know, is the likelihood higher that this is Man #1’s baby? (Disclaimer that this man is my husband — whom I have never been unfaithful to until now — so I’m really praying that it is). Assuming I DID ovulate at the exact moment on March 5 and the egg was fertilized and implantation happened exceptionally fast, does 444 seem like a high number for 12-13 days post ovulation? Likewise does 3955 seem high for 16-18 days post ovulation? I completely recognize that hcg is a difficult thing to go by and everyone has a range but in YOUR experience/opinion/expertise, do those numbers seem high for a March 5 conception date? Is the likelihood higher it is from the Feb 27/Feb 21 intercourse?One last piece of background, I had an ultrasound this morning (March 28) and they were only able to see a yolk sac (no baby yet). That would make the baby 6w2d for a Feb 27 conception and 5w2d for a March 5 conception. I go back again in 2 weeks for another ultrasound but in the meantime the technician said the baby could be anywhere from 5-6weeks (which is what I already know).I am just looking for a little insight into the numbers and likelihood of the different possible conception dates given your years of expertise and observations.Any and all help would be incredibly appreciated. Thank you.



Doctor: Hello,Thanks for the query to ATD for an opinion,A 4 weeks pregnancy would have a hcg level would be around 426-44 4 . So, considering that pregnancy was 4 weeks on MARCH 17, so date of conception should be around feb 22-24.Hence it is likely that the first man is likely the father of your child. A home pregnancy test would not have come positive if the conception would have been from march 5. A hcg level at 3 weeks pregnancy would have been 0 to 5 if the pregnancy would have occurred on march 5.I hope that i have answered your query in detail,Regards



Comments / Follow Ups

Patient: In your experience, which is more reliable this early on — hcg bloodwork or ultrasound dating?

Doctor: In my experience hcg blood work is more reliable than usb dating in any case unless its an ectopic pregnancy or a partial mole.

Doctor: *thats usg dating and not usb.


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Dr. Jimmy Obaji M.D.

Dr. Jimmy Obaji M.D.

Dr. Jimmy Obaji completed his residency in Family Medicine at the University of Manitoba. He currently operates a walk-in-clinic in downtown Toronto.

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