how to calculate POA by EDD. :)

assalamualaikum. since i got really excited of discovering this tonight, i decided to blog this. i hope at the very least, this will help some of us including myself. they said, if you're able to teach others on something, it means you really understand it.

so basically, for the concept.
POA=period of amenorrhea.
EDD=estimated delivery date
DOV=date of visit

let's say:

1) LMP=26/12/12
    DOV=27/8/13
    EDD=2/10/13 (just insert the formula from naegle's rule-LMP+(+7(d)-3(m) +1(y) ). seriously i don't think you guys will hv problem with this. simple maths calculation. :)
    POA= ? 

basically, they're two ways to calculate the POA.

a) LMP BASED
POA
= DOV-LMP
=  27/08/13 [DOV]
   -26/12/12 [LMP]
     1d 8m
convert to weeks:
=(8x4)w + 2w +5d + 1d
=34w+6d

 if you're not sure why i added up the 2w it's because for every 3 months you hv to add up 1 week (REFER TO PIC ABOVE). thus, because it is 8 months, means you have 2 times of 3 months in 8 months, you hv to add up a total of 2 weeks into the calculation.for the addition of 5d.

and the final answer u'll get is POA=34w + 6d

b)EDD BASED
POA
-first, manually count the days from DOV to EDD; in which:
DOV[27/8/13] to EDD[2/10/13]=4d+30d+2d
                                                  =36d
                                                  convert to weeks/36d divide by 7
                                                   =5w 1d
                                                   =40w -(5w 1d)
                                                   =34w + 6d
 -basically u'll hv 5w 1d from DOV to the estimated date of delivery(EDD). since usually EDD will be exactly 280 days or 40 weeks, thus, u can simply substract 5w 1d from 40w to get POA! this is so much simpler and highly recommended to use if the DOV is nearer to EDD, but of course, u can use either way, the one you found easier with better understanding.
-well, you might be asking why is the answer 34w+6d instead of 35w+1d. by right, you should get 35w+1d if you simply substract it using usual ordinary addition substraction methods. it's really hard to explain in words, but let me just give you another short example.
 let say if your EDD (23/8/13) & ur DOV (20/8/13). By right, u'll get 3days from DOV to EDD. so, if you wanted to count the POA using the EDD BASED method with usual maths substraction step, you'll end up like this.
POA=40w-(0w +3d)
        =40w+3d
-this is definitely wrong since the total EDD is only 40 weeks. the correct way is actually:
POA=40w-(0w+3d)
        =39w+4d
-by logic, i'm sure you hv no problem figuring out how on earth i ended up putting 39w+4d as the answer,. OR BETTER, I always substract it like this.
using the example from above:

DOV[27/8/13] to EDD[2/10/13]=4d+30d+2d
                                                  =36d
                                                  convert to weeks/36d divide by 7
                                                   =5w 1d
                                                   =39w 7d - (5w 1d) ; instead of using 40 weeks, convert it to 39 w 7d
                                                   =34w + 6d



well then, i shall get my sleep now. remember, practice makes perfect. so just came up with any dates and try to calculate the EDD & POA and compare it with ur friends. trust me, this helps!

hope this helps. anything just comment below k:)