Write SQL query to solve given problem: How many unmarried women were checked for normal pregnancy?. Keep the solution inside sql tag ```sql [SQL-Query] ```
SELECT COUNT(DISTINCT T2.patient) FROM conditions AS T1 INNER JOIN patients AS T2 ON T1.PATIENT = T2.patient WHERE T1.DESCRIPTION = 'Normal pregnancy' AND T2.gender = 'F' AND T2.marital = 'S'