Expert: Dorothy H, LCCE - 6/30/2009

Question
QUESTION: Need help with a conception date. My LMP was May 9th. I was with partner #1 from May 21st until May 25th. He ejaculated in me each day within these dates. I was with partner #2 late night on May 28th. He pulled out. I have a 28 day cycle that is right on target. I was expecting my period on June 5th. I took a home pregnancy test on May 31st that said negative and then again on June 5th that was positive (don't know if that helps). The ultrasound says that I am 7weeks and 2days today 6/29/09 and the due date is 2/14/2010. I know that my most fertile time is between May 22-25th according to the website calculators. Is it at all likely that partner #2 could be the father?

ANSWER: Hi Kelly,

As you know, your most likely date of ovulation was somewhere between May 22-25, which the ultrasound confirms.  The egg can live 24 hours, so even if you ovulated late in your cycle, on the 25th, the egg would have only lived one day, making the latest likely day for conception to occur to be May 26, two days before you were with Partner #2.


Especially with your cycles tending to be regular, combined with the likely dates of ovulation and conception, it is highly unlikely that Partner #2 is father of your child.

---------- FOLLOW-UP ----------

QUESTION: Thank you! Another couple of factors is that on June 6th my HCGs were 319. Up more than double two days before. On June 23rd the heart rate of the baby was 113 and on June 29th it was 156. Does this all also confirm partner number 1? I am only double checking because a certain website said that I could have been fertile all the way until the 29th...which seems to be a lot longer than what all of the other websites say and the doctors office said it was possible although unlikely. Maybe these other factors help confirm. Sorry...freaking out!

ANSWER: Hi Kelly,

If you conceived May 28-29, you would expect to see HCG levels well under 300 on June 6 (you would have seen levels around 10 or less on June 6 with a May 28-29 conception date)

A level of 319 on June 6 points to a conception date in the May 21-24 range.

The HCG test certainly makes it even more clear that Partner #1 is the father of your baby.

I never like to confirm paternity with certainty (and I'm sure your doctor feels the same way) but with the information you gave me, it is  extremely extremely unlikely that Partner #2 is the father.

I hope that helps!


---------- FOLLOW-UP ----------

QUESTION: Oh gosh! Whoops... I meant that HCG was 319 on June 8th. It was one hundred and something in June 6th. But it still sounds like it is still much higher than if conceived on May 28th/29th... so that is a big relief! You do still feel as strongly with this info right? :)

Answer
If you conceived May28/29, you'd expect to see HCG levels around 10 or less on June 6, not 100something.  You'd expect to see HCG levels definitely under 50 and probably under 30 on June 8 for a May 28/29 conception date.  You would not be seeing 300+ on June 8 if you conceived on the 28th or 29th.