import re

regex = r"\w+,\s*f\s*\.\s*\d\d-\s*\d\d-\s*\d\d\d\d"

test_str = ("Smith, John,\n\n"
	"f. 25-12-1990\n\n"
	"or only first part of below:\n\n"
	"Smith, John, f. 25-12-\n\n"
	"1990\n\n"
	"Smith, John, f. 25-\n\n"
	"12-1990")

matches = re.findall(regex, test_str)

print(matches)