Conceived May 8th according to 13 week 6 day ultrasound...

[TatianaNic]

Knowing this, what are the chances the conception occurred before April 30?

How many days off could an ultrasound be during this time? It's obviously more likely the conception happened after April 30th, which is what I want, but you never know. Just want to know how accurate you think ultrasounds at 13 weeks are!

All I can say is...can't always trust condoms. A DNA will be done, but that's quite a ways off.

 

[Angel_blues]

I would call it accurate.

 

[NDH]

There is a 1 week margin of error on wither side of the date given to account for babies growing at different rates, though generally the difference is only a day or two either side. Sperm as well can live up to a week before fertalising an egg. Given those two factors, yes its possible conception could have occurred before April 30th, but not terribly likely. Especially with "fresher" sperm being present iykwim.

But theoretically yes, if you BD April 30 and ovulation happened May 6 you could have conceived, and a 2 day difference from scan is well within the margin of error. You could have ovulated as early as May 1 and still been within the acceptable margin of error for your scan measurements. But its just as likely you could have ovulated later than May 8 which would be well and truly impossible.