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Ask Dr. Norm S. Your Own Question
Dr. Norm S.
Dr. Norm S., Board Certified OB/GYN
Category: OB GYN
Satisfied Customers: 11252
Experience:  Over 30 years of experience in OB/GYN practice, including teaching students. Fellow of American Board of Obstetrics and Gynecology.
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I have just tested positive on a home pregnancy test after

Customer Question

I have just tested positive on a home pregnancy test after being two days late for my period and there is a question of paternity. I had my last period starting on December 18, bled for 5 days. My normal cycle is 26 days. I had unprotected sex on New Years eve when I should have been fertile, and then on the fourth and fifth as well. I'm thinking that the man on New Years would be the father, but is it just as likely that the other man is? Is this too close together to be able to tell from an ultrasound whose it would be?
Submitted: 1 year ago.
Category: OB GYN
Expert:  Dr. Norm S. replied 1 year ago.

I think that it's most likely that the man on New Years Eve is the father. However, there is a possibility that you ovulated late, in which case the other man could be.

If you never have a late period, then most likely the man on New Years eve is the father.

An early ultrasound is generally accurate within 5-7 days. Since there's only 4-5 days difference between the 2 partners, an ultrasound probably won't resolve the question.

To be really certain, you might need DNA testing.

Customer: replied 1 year ago.
What about a blood test for the levels, would that determine if there is a difference in conception date?
Customer: replied 1 year ago.
I'm also wondering if there was enough time between the 4/5th and yesterday for the egg to be fertilized, travel down, implant AND produce enough hCG to show up on a non-early check test on the 28th day of my cycle. Because to me it seems like it would be more likely if it was a few days farther along aka New Year's day.
Expert:  Dr. Norm S. replied 1 year ago.

Blood levels of hcg vary so much from one woman to the next that they are nor really helpful.

You're correct that a pregnancy test might not be positive by today if you just got pregnant on the 4. However, it's not too unusual for a pregnancy test to be positive 12 days after conception, and can even be positive by 10-11 days after conception. So if you conceived on the 4th, today is 12 days later. Hcg starts showing up after implantation, and that usually occurs about 1 week after conception. Conception usually occurs the same day as ovulation, sometimes the next day.