Expert: Catherine Beier MS CBE - 4/9/2008

Question
My granddaughter was born 7/25/04.  I would like to know if you can tell me when conception might have occurred?  I do know that my daughter told me she had a sonogram on Feb 27, 2004, she said she was 4 months pregnant and that it was a girl.  From what I understand, she would have been at least 16 weeks at that time - so I'm guessing the 2nd week of November, however I'm just not sure.  I don't have access to her medical records and as the guardian for the child we're trying to determine "potential paternity" based on some information we've discovered.  Thanks.

Answer
Angela,

The information you gave is just too sketchy to give an accurate (or even semi-accurate) estimate.  The only true way to tell at this point is with a paternity test.  You didn't say if the baby was born on time, late or early and without knowing this or the date of her last period, the following is sketchy at best.

If she was 16 weeks pregnant at the time of the ultrasound, then conception could have occurred around the third week of November.  Ovulation usually occurs about 14 days before the end of your cycle.  This again will vary depending on whether her cycles are longer than average and/or irregular.  

However, sperm can live in the reproductive tract for up to 5 days, so if there were 2 partners relatively close together, then again, it will not be possible to determine paternity without a DNA test.


Best,
Catherine