topic Re: Date calculation at 3 months interval or trimester dates in SAS Enterprise Guide

Date calculation at 3 months interval or trimester dates

Sharan — Sun, 28 Aug 2022 18:55:47 GMT

Hi fellow SAS users,

I seek your help. I have a date variable which is pregnancy start date as preg_start. I would like to create 3 date vars: End of trimester 1, end of trimester 2 and end of trimester 3

I.e. I would like to calculate date at the end of each trimester.

Suppose my date is 1st jan 2005, I would like to have the output as follows:

Preg_start end_trimester_1 end_trimester_2 end_trimester3

1JAN2005 31Mar2005 30JUN2005 30SEP2005

Re: Date calculation at 3 months interval or trimester dates

PeterClemmensen — Sun, 28 Aug 2022 19:03:52 GMT

How do you define end of trimester dates? In terms of days after Preg_Start?

Re: Date calculation at 3 months interval or trimester dates

Kurt_Bremser — Sun, 28 Aug 2022 19:29:38 GMT

A pregnancy trimester is defined as 13 weeks or 91 days, so you simply add the number 91 three times (SAS dates are counts of days).

Re: Date calculation at 3 months interval or trimester dates

PGStats — Sun, 28 Aug 2022 19:44:21 GMT

If this is more than an exercise, I suggest that you refine your definition of "pregnancy start date" and "end of first/second/third trimester". A good place to start is the Wikipedia page on human Pregnancy.

Re: Date calculation at 3 months interval or trimester dates

Ksharp — Mon, 29 Aug 2022 12:05:48 GMT

data _null_;
x='01jan2005'd;
d1=intnx('qtr',x,1,'s')-1;
d2=intnx('qtr',x,2,'s')-1;
d3=intnx('qtr',x,3,'s')-1;

put (x d:) (= date9.);
run;