The period of time over which the whole play takes place is shown by Stella's pregnancy. Blanche moves in with her and Stanley when Stella is about four months pregnant. We can see her growing pregnancy by the costumes she wears. Then Blanche is still liviing in their apartment when Stella has to go to the hospital to give birth. So Blanche has been staying in that cramped apartment for about five months--and somewhere in the text Stanley tells one of his friends that Blanche has been with them for five months and that he is getting ready to kick her out. It is when Stella is in the maternity ward and Stanley is all alone with Blanche that he rapes her. Stella is at home with a brand-new baby when Blanche is taken off to an asylum. So the period covered is approximately five months. This is a clever way for Tennessee Williams to show the passage of time and simulteously to dramatize how Blanche's presence is becoming more and more of a burden and an intrusion on Stanley and Stella's privacy. By the time the baby comes, there is really no place for her in that tiny apartment.