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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: 11106
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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My name is ***** ***** and I have a question regarding

Customer Question

Customer: My name is ***** ***** and I have a question regarding paternity.
JA: Thanks. Can you give me any more details about your issue?
Customer: Yes my wife had sex with a man on May 28 and then sex with me on June 1 2015. She became pregnant and had an ultrasound done on July 21 at which time the doctor gave her a due date of Feb. 21 2016. Wanting to know if there is any way to rule out either myself or the other man as the father.
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Submitted: 1 year ago.
Category: OB GYN
Customer: replied 1 year ago.
The sex of the baby is a girl
Expert:  Dr. Norm S. replied 1 year ago.

The ultrasound of July 21 gives your wife a conception date of June 1. With such an early ultrasound, that day should be accurate within 5-6 days.

So there is no way to know from the ultrasound, since May 28 and June 1 are both within the range of error.

The only way to really know would be a DNA test. That can be done by a test of your wife's blood after 8 weeks pregnancy. There is more information here