Expert: Dorothy H, LCCE - 9/4/2010

Question
I am doubting the paternity of my child's father.  It's either my current boyfriend or my ex.  I don't know exactly which days I had sex with my boyfriend, but at the time we were doing it pretty regularly.  I slept with my ex once, on February 18th.  I know I made a huge mistake and it has been eating me alive since the day it happened.  Here are the other facts:

My LMP was January 27th
My cycles have always been pretty regular.  They have NEVER lasted longer than 30 days.
My period was due February 26th
I took a pregnancy test February 27th and it was positive
My EDD is November 3rd

I had an ultrasound on March 26th where the baby measured 8 weeks, 4 days
I had an ultrasound on April 9th where the baby measured 10 weeks, 3 days
I had an ultrasound on April 24th.  I don't remember exactly what the measurement was, but the tech did say he was right on target with my LMP.

How likely is it that this baby is NOT my boyfriend's?  I know the only way to know for sure is a paternity test, and I intend to have one done as soon as he is born, but I would really appreciate your input in the meantime.

Thank you so much.

Answer
From the information you gave, I don't see that there is any chance that this baby is not your boyfriend's. Definitely much less than 1% chance.

You have three 1st trimester ultrasounds showing conception occurring around Feb 8 or 9.  The egg can only live for a day after ovulation, not the 10-11 days that it would have to live in order for your ex to be the father.

The odds that three first trimester ultrasounds could be off by that much - it just doesn't happen.

I think the paternity test will set your mind at ease, and I'm sure it's going to show that your boyfriend is the father of your baby.

Try not to let it eat you alive.  Look at it as a wake-up call to continue to work on your relationship with your boyfriend, and as you start a family together to do whatever you can to both be great parents for your baby.

Dorothy H, LCCE