How to compute age of gestation

  1. Good day!
    It's been 4 years since I graduated from nursing school and I have forgotten how to manually compute the age of gestation (no to calculators/ob wheels please).

    I can't find a simple formula on how to compute it, google is just giving me results on how to do it via calculators.

    I can't find my college notes too.

    Can someone please help? Thanks
  2. Visit Lorodz profile page

    About Lorodz

    Joined: Sep '03; Posts: 283; Likes: 70


  3. by   tmartin83
    is it Nagele's rule???
  4. by   miss81
    Hope this helps...

    Do you mean Naegele's rule for calculating EDC/EDD?

    EDD = LMP - 3 months + 7 days (obviously adjust year accordingly)


    Are you referring to calculating gestational age from LMP?

    "If the mother has a regular period and knows the first day of her last menstrual period, gestational age can be calculated from this date. Gestational age is calculated from the first day of the mother's last menstrual period and not from the date of conception. For women who have irregular menstrual periods or women who cannot remember the first day of their last menstrual period, it can be difficult to determine gestational age using this method. In these cases, an ultrasound exam is often required to determine gestational age. American Pregnancy Association


    We also us fundal height OR McDonald's Rule starting at 20 weeks gestation: Measure from
    symphysis pubis to top of fundus.
  5. by   Lorodz
    Thanks for the replies. Not naegele's rule. I meant the age of gestation. Assume that the patient's LMP IS feb. 1 2010,the aog is 25 weeks and 2 days (thank u iPhone app) Back in nursing college, our professor gave us a simple formula to compute patients aog. I just forgot it now

    Thanks for the ultrasound suggestion, but im in the ER and some patients just comein and doesnt have any aog based on ultrasound... So we have to resort to the unreliable AOG counting.

  6. by   JenTheRN
    The wheels really do come in handy...I know we shouldn't rely on them, but they do work. Also, if you have a smart phone you can download an app that will calculate the gest age based on lmp or u/s.
  7. by   IamsarahLee
    If an infant was born on 5/14 at 41 weeks and 4 days, would the EDC be 5/4? I'm not sure why I'm having a hard time with this. I do not know LMP?
  8. by   klone
    5/3. 41 and 4 would be 11 days. 5/14 minus 11 would be 5/3.
  9. by   lovelyjoan
    For the computation of Age of Gestation, first determine the LMP for example you have given February 1, 2010. Then take note of the LAST CLINIC VISIT let's say the pregnant client visited the clinic for a prenatal check-up on July 30, 2010. Take note also that year 2010 is not a Leap year so there are 28 days for February.Add up the number of days for all succeeding months until the day of Last Clinic Visit.From LMP the computation is :

    February 28
    - 1 (LMP is February 1 subtract this from complete number of days for February, or whatever is applicable month) February 27
    March 31
    April 30
    May 31
    June 30
    July 30 (Last Clinic Visit)Sum total 179 days

    To get number of weeks, divide the sum total with 7 using the long computation method. The remainder serves as the days.
    So, 179 divided by 7 would give us 25 weeks and 4 days, approximately.
  10. by   lovelyjoan
    this is in reply to Lorodz' question about AOG computation.
  11. by   klone
    Really not necessary to bump up a 2 year old thread to answer a question that has long since been answered.
  12. by   cayenne06
    well now I want a handy formula to help me calculate gestational age! I'd be lost without my wheel.