2 doctors weighed in:

Please help figure possible conception date. Ex girlfriend had sex w/ me may 17th unprotect. may 30th unprotect other man. US said "8 weeks." no lmp.

2 doctors weighed in
Dr. Douglas Lawson
Obstetrics & Gynecology
1 doctor agrees

In brief: Conception day

Since you didn't provide a date the US was done, in this case if the US said 8 weeks 0 days you would go back 6 weeks exactly for the approximate conception date.
Even though she didn't provide an LMP, US due dates are worked as if patient had an LMP. An 8 week US is accurate within 5-7 days. However, in your case get a paternity test no matter what.

In brief: Conception day

Since you didn't provide a date the US was done, in this case if the US said 8 weeks 0 days you would go back 6 weeks exactly for the approximate conception date.
Even though she didn't provide an LMP, US due dates are worked as if patient had an LMP. An 8 week US is accurate within 5-7 days. However, in your case get a paternity test no matter what.
Dr. Douglas Lawson
Dr. Douglas Lawson
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