How to calculate how many weeks?

[daisytumble]

My cycles are about 35/36 days which of course is 5 weeks

Despite this I think I’m ovulating around day 18.

TTC soon, when I do become pregnant how do you count the weeks with such a long cycle? As testing on the day of a missed period you’d already be 5 weeks with this cycle length.. surely not?

The will work it out from the first day of your last period. Doesn't take into account varying cycle lengths. Although if you know your ovulation date then there are calculators online that may work out your due date slightly more accurately. Not that babies come when they are due!!

www.nhs.uk/pregnancy/finding-out/due-date-calculator/

Adjust cycle length

To begin with they just use the first day of your last period. At your 12 week scan they calculate it from babies measurements. The 12 week scan can actually be any time from 10-14 weeks, so it doesn't need to be dated that accurately to book that in.

Midwives will always go by the date of your last period to start with and then that will be adjusted at your 12 week dating scan if needed.

Usually you ovulate around 2 weeks before your period so if you want it to be more accurate then just count yourself as 4 weeks from the day your period was due and then count on from there to work out an approximate due date, but that will just be for you