Um, it specifies exactly when she ceased being unmarried.
Just like the sentence "they had no relations until she had given birth" must mean they had relations immediately after the birth. If you want to read this as an affirmation of their having relations, as opposed to a statement of her virginity before the birth.
The verse is meant to convey that she was virginal prior to Jesus' birth. That is all.
SD
Just like the sentence "they had no relations until she had given birth" must mean they had relations immediately after the birth.
No ... they likely had relations within the same period of time after the birth ... that husbands and wives do after the birth of their children today.
The fact that we waited, having achieved a certain point in our pregnancies, until the actual births of our children, to resume relations ... does not mean that we had relations in the hospital.