QuestionQUESTION: Hello, I want to thank you in advance i hope you can bring
me some peace of mind. First of my lmp was 6/12/10 I have
very regular 28 day cycles. I had unprotected sex on the
night of 6/26 and morning of 6/27. I also had sex early
mornin (2 am) of 7/5 but it was protected a condom was
used it never broke. My period was expected 7/10 it never
came, I took 3 early first response pregnancy test on the
evening of 7/11 and they all came back positive. I had 2 first
trimester ultrasounds one match my lmp putting conception
on 6/26 and the other only one day behind putting
conception on 6/27. My question is how confident can I be
that I conceive on 6/26 or 6/27? Are first trimester
ultrasound pretty accurate? Would a pregnancy test would
have been positive on 7/11 if i conceived on 7/5?
ANSWER: You can be confident that you didn't conceive on 7/5, so if the only other choices are 6/26 and 6/27, then that's when you conceived. An early ultrasound is accurate to less than 7 days, so that makes 7/5 unlikely but probably doesn't rule it out. However, there is no way a pregnancy test would be positive on 7/11 if you conceived on 7/5, since it generally takes a week for implantation, and the HCG hormone doesn't begin increasing until after that. So 7/5 is out as a date for conception.
---------- FOLLOW-UP ----------
QUESTION: What would be the earliest a woman can take a pregnancy test with a
low sensitivity? If i have always had a very regular 28 day cycle what
would be the earliest and latest i would ovulate or earliest and latest i
can conceive? Also thank you soo much for your help! I just needed
peace of mind by making sure i didnt conceive the early morning of 7/5
and now i can be confident with your anwser and also because a
condom was used.
AnswerThe earliest is about 10 days after conception. With a 28 day cycle you would normally ovulate day 14. Stress and other things could make that later, but usually not earlier. You can get pregnant having sex 2 days before you ovulate or 1 day after, since the sperm live 2 days and the egg lives 1 day.
