data anlysis

Hello. I am wondering if something is possible. Some example data is below. The rows are different patients. Columns B - K are the dates they came to visit the clinic. Columns L - U are the type of birth control they are using during that visit. (I am only interested in LARCs.) The last column is the date the patient gave birth. I want to know how much time has elapsed after the patient had a LARC to when she gave birth. For example, for patient 1, she had a LARC during visit 2 which was on 1/2/2011. Then she gave birth on 12/2/2011. So 11 months passed from the date she visited using LARC as a birth control to the time date she gave birth. Is there a way to calculate the minimum number of months that have passed from the time the patient was using a LARC to the time they gave birth for each patient?

In row 2, say column W, this formula array-entered (that's Shift+Ctrl+Enter, not just Enter):
=DATEDIF(INDEX($A2:$K2,MAX(($L2:$U2="LARC")*(COLUMN(L2:U2)))-10),V2,"M")
and copy down.
You can surround the formula in an iferror function to hide the errors.