Help !

[Kmc777]

When did I get pregnant ! I had sex February 13-16 and had an irregular period on the 26th (I never have irregular periods) then March 8th I had sex with my ex I had my first ultrasound April 18 and I was 7 weeks and 3 days everything is saying implantation was feb 26 but the due date and conception calculator apps all say I got pregnant in March

[AnnieBrooke]

Here is why you can't understand the gestational age ("weeks pregnant") figure.  If a doctor, nurse, or any medical person says you're 7 weeks "pregnant", it is not a figure that counts back to conception but to two weeks before conception, to the first day of your last period.  All medical counts of pregnancy (the number like 7 weeks 3 days or 11 weeks 4 days) begin on the first day of the last period you had before getting pregnant.  If a doctor says to a woman, "Congratulations, you are 7 weeks pregnant!" he means 7 weeks since her last period began and about 5 weeks since conception.  

The count is done this way because that is they way it was done historically.  Before ultrasounds, they needed somewhere to begin the count.  The period is a big, obvious signal.  The doc does not think you are pregnant when you are on day 1 of your cycle.  (The doctor knows you were not pregnant then -- you're having a period!)  But that is where all medical textbooks, reports, scans, and medical people begin the count.  That is why pregnancy, which takes 38 weeks, is counted as being 40 weeks long.  They add a spare two weeks at the front to be able to calibrate the count to the presumed first day of the last period.

Sometimes the weeks 'pregnant' given to a woman by a doctor does not align perfectly with when the first day of her last period really was. This is because a lot of women don't ovulate neatly two weeks after the first day of their last period.  The ultrasound sees and measures the actual embryo, so a woman who gets a GA count that doesn't line up with her real period should date the conception as being the GA count, less two weeks.  When the doc told you that you were 7-plus weeks 'along' or 'pregnant,' he was saying your embryo measured about what an embryo measures that had been conceived 5-plus weeks ago.

[AnnieBrooke]

Hi, if you had an ultrasound April 18 that said you are 7 weeks 3 days, *nothing* is saying implantation was February 26.  Everything is saying it was March 11 give or take a day, well, everything except your assumptions you are making.  This misunderstanding of what the doctors are telling you is because of the way doctors count "weeks pregnant."  They begin two weeks before conception, or at what would be (in an average woman with average cycles) the first day of her last period.  This is because historically that is all they ever had to begin the count.  Now with ultrasounds, they have more information, but the count is still calibrated to begin at the calculated first day of last period, so it makes a 266-day pregnancy into 40 weeks.  I have to step away from the computer at the moment but will come back later and post my usual info on why that happens.  But what it means for you is that the March 8 sex is very much in play.  When did you then have sex after March 11 with your ex?