This query will figure out how many children will turn 2 years of age if the future birth date is known, it rolls forward in 2 month periods.

select_children_turning_an_age.sql

SELECT
CASE
-- -- Child turning 2 within 2 month periods
WHEN ue.baby_due_date BETWEEN DATE_SUB(NOW(), INTERVAL 16 MONTH) AND DATE_SUB(NOW(), INTERVAL 14 MONTH) THEN CONCAT(DATE_ADD(CURDATE(), INTERVAL 8 MONTH ), ' to ', DATE_ADD(CURDATE(), INTERVAL 10 MONTH ))
WHEN ue.baby_due_date BETWEEN DATE_SUB(NOW(), INTERVAL 18 MONTH) AND DATE_SUB(NOW(), INTERVAL 16 MONTH) THEN CONCAT(DATE_ADD(CURDATE(), INTERVAL 6 MONTH ), ' to ', DATE_ADD(CURDATE(), INTERVAL 8 MONTH ))
WHEN ue.baby_due_date BETWEEN DATE_SUB(NOW(), INTERVAL 20 MONTH) AND DATE_SUB(NOW(), INTERVAL 18 MONTH) THEN CONCAT(DATE_ADD(CURDATE(), INTERVAL 4 MONTH ), ' to ', DATE_ADD(CURDATE(), INTERVAL 6 MONTH ))
WHEN ue.baby_due_date BETWEEN DATE_SUB(NOW(), INTERVAL 22 MONTH) AND DATE_SUB(NOW(), INTERVAL 20 MONTH) THEN CONCAT(DATE_ADD(CURDATE(), INTERVAL 2 MONTH ), ' to ', DATE_ADD(CURDATE(), INTERVAL 4 MONTH ))
WHEN ue.baby_due_date BETWEEN DATE_SUB(NOW(), INTERVAL 24 MONTH) AND DATE_SUB(NOW(), INTERVAL 22 MONTH) THEN CONCAT(CURDATE(), ' to ', DATE_ADD(CURDATE(), INTERVAL 2 MONTH ))
ELSE 'Out of ranges'
END 
AS my_ranges,
COUNT(*) AS baby_count
FROM table AS ue
GROUP BY my_ranges
ORDER BY my_ranges

/*

Will produce something like this

my_ranges	           baby_count
---------------------------------------
2014-04-04 to 2014-06-04  |  4
---------------------------------------
2014-06-04 to 2014-08-04  |  16
---------------------------------------
2014-08-04 to 2014-10-04  |  13
---------------------------------------
2014-10-04 to 2014-12-04  |  8
---------------------------------------
2014-12-04 to 2015-02-04  |  23
---------------------------------------
Out of range	          |  43
---------------------------------------

*/