Conception

[Aimee009]

My LMP was on January 15th and I have a fairly regular cycle length of 29-30 days. I had sex with guy A on January 24th (I used PlanB within the 72 hour recommend window and he also pulled-out) and with guy B on January 30th (No PlanB). I had a free ultrasound done at a clinic on March 5th and was told that I was measuring 6 weeks and 6 days, with a due date on October 23rd. I used one of those online calculators and it estimated my conception date to be January 30th. Would this make it guy B's?

I then sought out a regular doctor and received another ultrasound. They based the due date off of my LMP and put it at October 22nd, with me being 8 weeks 4 days. The ultrasound measurements put me at 8 weeks 6 days with a due date of October 20th. Would the earlier ultrasound be more accurate in terms of measurement?

[AnnieBrooke]

Too late for implantation, I think.  

[Aimee009]

Alright, thank you for the response. I was also wondering if implantation bleeding is a real thing and when that normally occurs? I had spotting on February 11th and had a low grade fever for a couple of days. I read that could be an indicator of when implantation occurred.

[AnnieBrooke]

I don't think Plan B delays ovulation, it creates a hostile environment for the embryo to implant or possibly to stay implanted.  But the problem there is that there is a 1 in 8 chance that Plan B will not work.

But it does sound like assuming you ovulated around January 30 or so is a reasonable assumption.  It is not something I would use to convince myself that I didn't need to do a DNA test when the baby is born, but in your shoes I would assume (as a working assumption) during the pregnancy that the second guy is the dad.  Test when the baby is born.

[Aimee009]

Yes, that is my concern. I was also trying to see if that would most likely be a non-issue since I took PlanB which would have delayed ovulation, making it more likely that I ovulated closer to the end of the month. Also, I had read in a different thread that regardless of cycle length, ovulation always precedes the start of the next period by 14 days. The earliest I would have expected my next period would have been February 14th, putting my ovulation date at January 31st.  

[AnnieBrooke]

Probably.  A 6w6d ultrasound is usually more reliable for dating a pregnancy than an 8w6d ultrasound, but this would depend totally on how good the ultrasounds are at a free clinic.  October 20, 23 and 24 are all pretty close together.  Even the  earliest of the three due dates suggests you conceived no earlier than January 27, and that one is from the latest ultrasound you had.  Is what you are worried about the idea that you had sex on the 24th, some sperm was present, and it stayed around until the 27th?