Question about pregnancy for any Americans here

[HollowTalk]

Over in the UK we date a pregnancy from the start of a woman's last period, so if she's a week late, she's considered to be five weeks' pregnant.

Is it the same over in the US? I am writing something for the American market and this has been picked up by my editor and my copy-editor - they seem to date a pregnancy by the date of conception. Is this what happens over there?f

Please help!

In France they go by date of conception. It makes more sense, but makes it confusing for me as a Brit living in France. Generally I think of the 2 due dates and assume baby will arrive sometime in the middle. The advantage is that in France they don't let you go far over your due date before intervening, rather than waiting a week or 2 like in UK.

What is the logic for dating this way?
If you don't have a regular cycle does it have any consequences in terms of understanding if you actually need to be induced or not because you are considered at 42 weeks?

At the beginning of pregnancy this is the only thing they have to go on really, as nobody can be sure the exact date of conception.
All (healthy) embryos grow at the same rate so at the 11-14 week dating scan they measure the baby and give a more accurate due date. All further dates are based on this, not the last period date.

Is it the case that the due date in France calculated at what would be 41 weeks in the UK? How do they work out when you conceived?

They do a dating scan but they can also revert to the calendar method. 39 weeks is considered 'full term' so if your 12 week dating scan puts your baby at a reasonable date to confirm your due date 39-40 weeks minus 12ish then they will go by that. They tend to wonder out loud if you remember your LMP correctly too.

OBs in the US tend to be very risk averse as they pay incredibly high professional malpractice insurance premiums (can be over $100k per year). So actually their decisions about induction, etc., will be dictated by their malpractice insurance company, or that issue will at the very least be at the back of their minds.

None of mine had a little hat put on until a few hours after birth. They were swaddled in typical flannel hospital blankets and wore their little hospital sock-hats (a tube of mesh style white cotton fabric with a knot at one end). Also little hospital issue cotton vests.
Happy memories .
I think I may still have a little hat somewhere.
www.npr.org/2011/07/22/138575125/born-in-the-usa-this-blanket-might-look-familiar

I'm just had a baby in Poland and had 2 due dates. One from the first day of my last period and then another when the baby was big enough to date from a scan. I suppose then I would have had an idea about when he could be born. In the end he was 5 weeks early so didn't matter but I think that's a pretty good way to do it.

The ultrasound machine my French doctor uses is made in America and the due date that shows on the screen is 10 days earlier than the due date my Dr gives me. When I asked about it the reason seems more about managing the parents expectations (in UK mother is stressing about more than a week late but in France you're not due yet). I have a friend who reached her French due date and was then induced immediately when she was 1 day late here.