Expert: Catherine Beier MS CBE - 9/8/2008

Question
QUESTION: Please help me....I had my last menstrual period on 28th July 08 which lasted only a few days (I do not have regular cycles as they have ranged from 24-30 days over the last 8 months). After which I had intercourse on 4th/5th August with my boyfriend. However, on the 10th August I stupidly slept with another man. Approx 42 hrs later, on 12th August I took the morning after pill. I found out I was pregnant on 26th August when I had a positive pregnancy test and have had bloods checked for hcg levels, which were 364 on 28th Aug and 900 on 30th Aug. On Monday (1st Sep) a gestational sac was visible through a transvaginal scan for the 1st time which measured 4mm. However, the hospital have used the date from my LMP, which is not much help. Given this information, is it more likely that this baby is my boyfriend or the one night stands? Please help

ANSWER: Lisa,

Based on what you've indicated, my money is unfortunately on the one-night stand.  That encounter happened during the most probable fertile time in your cycle.  Ovulation typically occurs about 14 days before the start of your next cycle, meaning the timing would have been excellent for conception to occur.


With your first partner, it's less likely that you would have been ovulating at that time, although it's possible since you indicated you have irregular and sometimes short cycles.


So, while it could be either, the signs point toward the second man.  This is also more consistent with the development that was seen via the ultrasound.



Best,
Catherine

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

QUESTION: Thanks for your reply, I just wanted to know would it have made a difference that I took the morning after pill 40 hrs after the incident with the 2nd man? Has this not worked with him or is it a possibility that I may have already been pregnant?

ANSWER: Lisa,

The pill didn't work in either case.  Either you were already pregnant from #1 or you still conceived from #2.  Truly, the only way to be absolutely certain which man is the father is with a paternity test, although #2 seems more likely from the information provided.



Best,
Catherine

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

QUESTION: Thanks Catherine, I am going to take your advice and have a prenatal DNA test carried out. I have been looking into having this done through the CVS method. Do you know what is the earliest stage that this can be carried out? Also, are there any other methods that can be used?

Answer
Lisa,

There are two types of prenatal paternity tests: CVS (Chorionic Villi Sampling) and Amniocentesis.  

CVS is performed during the 10th to 13th week of pregnancy.

Amniocentesis is performed during the 14th to 24th week of pregnancy.


There are risks and benefits to each.  You can talk to your care provider about which option is best for you.




Best,
Catherine