Does cycle length affect due date?

[PixieCake]

Something I saw on another thread made me wonder:

If your menstrual cycle was less than 28 days, is your baby more likely to come before 40 weeks? I'm wondering if the 40 week thing is based on a number of cycles rather than actual weeks.

Reason for asking is I need to schedule in a c section for either 2 weeks before or one week after due date, so trying to estimate my chances of being early or late.

Thanks

Most due date calculators take into account your cycle if you know your cycle is shorter or longer than 28 days this will slightly effect your due date (which IME is only an estimate)
Does that help?

Your GP/midwife should have calculated your due date based on your cycle length anyway so it doesn't matter.

So for example, someone with a 28-day cycle would be 4 weeks exactly 4 weeks after the first day of their last period. If you had a 35-day cycle then you would be in effect only 3 weeks pregnant at that stage because your due date would be moved forward a week to take into account a later ovulation and therefore conception.

Its not the length of your cycle - its when you ovulate. You could have a long or short cycle and still ovulate fourteen days before your period. If you are charting with TCOYF or similar, or using ovulation predictor kits you will know when you ovulate - if not, you won't, so you are best to pick a mid cycle date.

They do your estimated due date based on the rate of growth of your baby at the 12 week scan.

Agree with pinkgrapefruitjuice re scan measurements will be used by docs to estimate due date. they will disregard any previous estimate you have given them based on LMP/ovulaton etc.

Once you have conceived,it takes the same amount of time to grow a baby no matter how long your mentrual cycle is.

Are you asking "is the pregnancy length less than 40 weeks if you normally have a short cycle"? If so, I think the answer is "no" - the baby needs 38 weeks from fertilisation to birth (give or take!). You add on 2 weeks, to make 40 weeks gestation, in theory backdating to the date of your last period, but obviously this assumes a 28 day cycle with ovulation on day 14.

As the others have said, scans will fairly accurately date a pregnancy and predict "due" date

hth