My son's girlfriend had an ultrasound on Thursday Mar 3 the women that did the ultrasound said she was about 10 weeks but when radiologist read the it they said 11 1/2 weeks don't know which one would to believe. Here is the thing my son and this girl did not start having sex till after Christmas and I am questioning that fact that it may not be his.

Unfortunatately, dating by ultrasound is not an exact science. With such a small date range, the only way to know parentage is by DNA testing.