How is number of weeks of a pregnancy calculated?

ideally the EDD is calculated, taking last date of menstrual cycle as day one of pregnancy, for simplicity.Hence, they say she is 5 w 6 d pregnant.Also generically, the menstrual cycle period is taken to be 28 days.
check this out
Pregnancy Due Date Calculator | Tools | BabyCenter

 

you can take an average of 30, but the most accurate is when she has her scan, they will let her know the weeks. depending on the size of the fetus and other factors.
please ask her to speak to her doc for a more accurate calculation.

usually the cycle is counted as 28 days for simplicity , and although my cycle has been 30-31 days since last 6 months, she never asked me about it, and gave me a generic answer about my pregnancy when i first visited her, ofcourse my first scan is still due.

 

Hi babychinnu,
If she has 4-5 cycles of 32 days that means she needs to calculate her day as 32 days...because you average cycle is counted by last 4 cycles.

so if she had her periods on 16th jan and 32 days length suppose.
then 32-14 (14th is lutheal phase ie days after ovulation till next period) so she probably ovulated on her cd 18 ie 2 nd feb...and from then then counts days till 26th feb =24 days
divide this by 7 = 24/7= 3weeks 3 days
now add 2 weeks to get you weeks of pregnancy
then she should be 5 week 3 days...

But if she is 5week6 days pg that means she ovulated 3 days early that cycle ie on cd15 and her would have been 29days that month.

This is what technique my doctor use for PCOS and irregular menses..

Note :-
ALso Ultrasound are never accurate till you are 8 weeks pregnant as baby is really very small to count ..so dont worry till you are above 8 weeks

ENjoy your pregnancy !!

 

you can also ask your friend to visit prenology.com to get correct weeks of her pregnancy

 

No dear...It should be calculated from ovulation day and add 2 weeks...or from day of your AF due date +4 weeks...unless you have very regular cycle of 28 days...if more or less than 28 then this is the way...

If you want you can tell me LMP, how long is the cycle from last 4 months and your AF due date...than i can tell you exact weeks pregnancy

 

Hi,

My gynaec told me since my menstrual cycle is 32 days, you should consider 2 weeks delay from the first day of your menstrual period. For 28 days cycle the EDD can be calculated from the first day of your menstrual period.

i.e. Suppose my first day of menstrual period is August 8, 2009
August 22, 2009 will be the first day for the 32 days cycle considering addition of 2 weeks.

Regards,
Lynette