The description below the image of the index says "Entries give names of parents, date of birth, and birth certificate number. The name of the child is not indexed because sometimes this information does not appear on the birth certificates." So E-97344 is the birth certificate number. The Maryland Motherload page says "birth records in Maryland are restricted for a hundred years, hence the 1922 cut-off on publishing copies of actual certificates". It sounds like a 1939 certificate would probably be at the Maryland State Archives but can't be published online until about 2039.