Paternity query

[Benj21]

My girlfriend is 14 weeks pregnant today (28/06/2016). 14 weeks is the date given by ultrasound but this also exactly matches her LMP of 22nd March. We have known each other for 3 years but we got together on 5th April and we only found out she was pregnant on 24th April after a missed period.

We have only been together for 12 weeks but she is 14 weeks pregnant however I've heard that you should take 2 weeks off the ultrasound dates to get the correct age of the baby which would obviously line up with the dates we first had sex.

I've put the babies due date (27/12/2016) into online conception calculators and they come back as the date of conception being between 5th April and 9th April depending on her cycle lengths. It looks like we were just fortunate enough to get pregnant on the first day we had sex but I'm just looking for someone else's views on if I'm correct in thinking this? Or is there a possibility that it's someone else's? She did sleep with someone else the week before we got together.

It does however seem to me that everything lines up for it being mine and she got pregnant on the first day or a couple of days after that.

Thanks for any comments

[AnnieBrooke]

Well, frankly, the gender really won't help.  A boy might mean a 1% difference in the odds of the two guys, if it matters at all.

[Benj21]

Ah ok I didn't think it would.

I'll just see what happens at the end and hope until then.

Thank you very much for all of your time and help :)

All the best.

[AnnieBrooke]

Knowing the gender might help a little, but it will not be definitive.  At only 4 days apart, the sex was just too close together, especially because the desired father is the second guy and sperm lives a long time in the woman's body.  If this is super important to know immediately, you could spend the nearly two grand and get a DNA test before the baby comes (from Ravgen or the DDC), or else just do a DNA test after the baby comes for about a tenth of the cost.

[Benj21]

I'm curious how the gender might help even a little bit? Just for a bit more peace of mind.

Thank you for the advice. We already agreed we are going to do the DNA when the baby arrives anyway just to be sure of the father.

Although knowing earlier would help me adjust its not really necessary, obviously I want this baby to be mine but even if it isn't it's not going to make any difference to our relationship. She hasn't intentionally gone out of her way to cheat on me or anything like that as it happened prior to our getting together. I want it to be mine but I'm  more than happy to support her and be with her regardless of the outcome.

Thank you again for all of your help and your time.

[AnnieBrooke]

The fact that the measurement does also exactly match her last period date is why I asked.  It could mean simply that everything is consistent, the period and the ultrasound, which wouldn't be unusual.  It could sometimes mean that a doctor or nurse just plugged that date in when it was given in the intake interview (they always ask the first day of the lmp) and never corrected it based on ultrasound measurements.  But it sounde like you do know that it was the ultrasound that was where the estimated due date came from, and that is the best source.

That all said, because she slept with the other guy on the 1st of April, that's uncomfortably close to April 5.  I assume it's too early for her to know if the baby is a boy or a girl?

[Benj21]

I'm fairly certain it is just from the ultrasound measurements as no date was showing before they took the measurement and the sonographer specifically said the baby was measuring at that date.

Yes it's too early at the moment but we do have a private scan booked in for 2 weeks on Saturday which we are hoping to find out the gender at. Would the gender help in this or is it merely a case of hoping for the best and doing a DNA test when baby arrives?

Thank you so much for your comments.

[AnnieBrooke]

Hi, when I asked "Do you know for sure that the doctor used only the ultrasound measurements of the baby in computing the gestational age?" I meant versus just hearing when her last period was and typing that in, and not using the ultrasound measurements to contradict that information if they did contradict it.  It would be fine if only the crown-to-rump measurements were used to give her an estimated number of weeks.  Better than if the only thing they used was the first day of her last period.

Do you know any more about when she slept with the other guy?  You said the week before you got together, was it for example March 30 or was it April 4?

[Benj21]

Ah no my apologies.

They didn't input any information the dates given where from the measurement only.

However the measurement does also exactly match her last period date can this happen or am I just being dim?

She slept with the other guy on 1st April which is pretty close. I'm hoping the fact that he pulled out is our saving grace but I know it's possible to get pregnant from precum too so I'm a little worried about that.

Thanks again for your responses.

[AnnieBrooke]

Yes, you could certainly have gotten pregnant on April 5.  When was her first ultrasound, only the one from her 14th week?  Or did she have any earlier ones?  And was the sex with the guy from the prior week unprotected?  Sorry to have to ask, but these are pretty slim margins.

You are correct, by the way, that gestational age counts (the "weeks pregnant") used by doctors begin on an assumed date of the first day of the last period, which calibration is made by the ultrasound machine.  Do you know for sure that the doctor used only the ultrasound measurements of the baby in computing the gestational age?

One problem is that if the sex she had in the week before April 5 was unprotected, sperm can live 5-6 days in her system.  This could mean that both of you had viable sperm in her body at the same time, on April 5.  The other problem is that if the only ultrasound she has had was the one in her fourteenth week, there's a margin for error by now of at least +/- 7 days when trying to use an ultrasound to determine a conception date.  That is why I asked if she had any earlier ultrasounds.

[AnnieBrooke]

(My first sentence means "Yes, the two of you could have gotten pregnant on April 5."  I know you're the guy.)  

[Benj21]

Thanks for your response.

Yes she had an early scan at 8 weeks and the dates match up exactly to the correct date at the 14 week one if that makes sense.

Yes it was unprotected as well but she says that he pulled out.

I have no idea on the method used at the ultrasound I'm afraid it was just the date they gave from the crown to rump length.

I hope this helps and thanks for your comments so far.