The number of people allowed in the delivery room will vary by hospital. Some hospitals have strict rules allowing only two or three people in the room at one time. Typically, that means the partner or coach and one other guest.
Other hospitals allow an unlimited number of guests as long as those guests don't interfere with care of the pregnant woman or take up too much space in the room.
The rules set forth by the hospital may change based on time of delivery. If the birth is taking place in the middle of the night and “business” is relatively slow, more guests may be allowed.
If you know how many people you want in the delivery room, contact the hospital early for a tour. During the tour, ask about delivery room attendance. If there are strict rules in place that don't allow for flexible guests you may have to revise your labor and delivery plan.