calculating date of conception

[waelk38411626]

hello every one.

I need help pleas, 

I neede to calculate a date (date of conception)

I have a field which I call Terme LCC = 9 SA 6 Js whiche meens 9 weeks and 6 days 

I need the date befor 9 weeks 6 days 

thanks

[try67]

Date before what? The current time? If so, should it update each time the file is opened? If not, then when?

[waelk38411626]

it's the length that changes, each time I have a new length, I automatically get an age for the embryon.
I want to know the date of conception based on this age.
example: length: 20 mm => embryo age 8 weeks and 4 days
conception date: (the date before 8 weeks and 4 days).
thank you

[waelk38411626]

and if I have a lenth 25 mm this give me 9 weeks and one day

[try67]

But again, compared to what it should be calculated, and when should it be updated?

[waelk38411626]

COMPARED DE THE DATE PF THE DAY 

[try67]

OK. Should it be updated when the value of the "length" field is entered, then?

[waelk38411626]

if the day change and the lenthe change => date of conception changes

Date : 22/02/2022 

lenthe embryo : 16.9 mm that gives pregnancy  8 weeks + 1 days

date of conception : the date befor 8 weeks and 1 day "10/01/2022"

[waelk38411626]

if the day change and the lenthe change => date of conception changes

Date : 22/02/2022 

lenthe embryo : 16.9 mm that gives pregnancy  8 weeks + 1 days

date of conception : tghe date befor 8 weeks and 1 day

[waelk38411626]

yes the date befor the current time 

and it should be update each time the lenthe changes withe the date