Rosie O'Donnell

It's a bit of a legend, to be honest, okay?

So the standard way we work it out here in Oz is you take the first day of your last menstrual period and you add 280 days or 40 weeks to that date.

Sounds straightforward, but pregnancy isn't always a neat nine-month package like the calendar suggests.

And neither are cycles either.

Yeah, exactly.

So the 40 weeks is based on an average 28-day menstrual cycle, assuming ovulation happens on day 14.

But not everyone's cycle plays by those rules.

Some females ovulate earlier, some later, and the date can shift.

Plus months aren't all the same length, so you've got 30-day months, 30-day months, and then you've got February as well.

But here's the kicker.

Only one in 20 babies will actually only arrive on their due date.

Most babies will come either two weeks before or two weeks after.

So the due date is more of a rough window, not a ticking clock.

So early ultrasounds in pregnancies can help us estimate early

gestational age, if we're not really sure when our last menstrual period was or if there's cycle regularity.

And if things start to stretch beyond the due date, then you've got your treating team that will help guide you through that.

So don't stress about the due date.

Baby is not likely to come at that date.

I love these consults.

Like I'm a GP shared antenatal care provider.