How many unmarried women were checked for normal pregnancy?
unmarried refers to marital = 'S'; women refers to gender = 'F'; normal pregnancy refers to conditions.DESCRIPTION = 'normal pregnancy';
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'