I really SHOULD know this but I still don't understand the 28 day cycle . Even after sodding googling

[sagacious]

I can't believe how stupid this sounds but I have a real mental block on this.

If I started my period on say the 1st January, when would my next period be due?

A) 28th January
B) 21st January

I never know when I'm due on (when pg and asked about my cycle I just muttered 28 days)

Please put me out of my misery

If you have a cycle that lasts 28 days it would be A

i think you count from the 1st day of your last period as to when your cycle starts

28 day cycle means 28 days from one period to the next - so the 29th.

Out of interest - where did you get the 21st from ?

I would say it would be around the 29th if you had a 28 day cycle. You would need to track the dates of your periods to work out what cycle you are on as it differs from woman to woman. From babycentre:

The normal menstrual cycle lasts between 21 and 35 days. So, for example, a woman with a 28-day cycle would start a period every four weeks while a woman with a 21-day cycle would start hers every three weeks. When doctors talk about the length of the cycle they include the days of the period.

Most women ovulate around 13-14 days before a period. If a woman has a 28-day cycle, this means ovulation will be right in the middle of a cycle. However, a woman who has a 21-day cycle will ovulate around day seven. This means seven days from the start of a period - she might still be on a period on the day she ovulates.

If your periods are very regular then it is fairly easy to work out when you are likely to be ovulating. If your periods are not regular then it is not so easy. Doctors suggest that you keep dates for a few months. If you sometimes have a period every three weeks and sometimes every five weeks then you could be ovulating any time from day seven to day 21.

If your periods are very irregular you may not be ovulating at all or infrequently. Again keep dates and if you are trying for a baby and have no success after six months, see your doctor.

Bleeding which occurs between periods should also be reported to your doctor. If bleeding happens after you have sex you should get an appointment with your doctor as soon as you can.

Throkenholt .. I think I might have confused the 21 day thing with ovulation, but then after reading Seona (thanks! btw) link thats after NOT before.

I get it now (sort of) WILL mark dates in my diary from now on!

(I told you I have a mental block !)

Thanks everyone!

worth keeping track for a few months - most women (me included) have never had a 28 day cycle - mine is nearer 31-33 days.

Ovulation is 14 days before the end of the cycle normally (I think). Can be less if you have a short luteal phase.