If Andrew was born in February by the church book, and 2 mo. in this printed notice (mostly about his progeny), it would seem to indicate New Style dates for the rest of the document; therefore 10 mo. for example is October.
On the other hand he might have known his own birth date, not from Wicksell's church book, but from a family record kept by his own parents in Old Style -- in which case he would actually have been born in 1765, but in 12 mo. (February).And baptized the following month, in March 1766.
I only suggest this as a possibility; the record pasted into my hymn book clearly says 1765, but I agree with Peter that 1766 (New Style) must be the correct date as we now reckon dates.