Many doctors and midwives will tell you when you need to call or will be available for you by phone during the earlier parts of labor. Have the phone numbers handy and some general information available prior to calling. Generally they will want to know the length of the contractions, how far apart they are and if the water bag has broken or not.
If you're having a home birth your practitioner may come over earlier to check on you and make calls back and forth until you're ready for them to come for the birth.
Getting to the Hospital in Labor
If you are not planning a home birth, you will probably go to the hospital or birth center towards the end of this stage or early into the next stage. Prior planning on the route, special considerations for the time of day or road closings will make this an easier trip. Many women will also feel better with a few pillows in the car. Some people may be concerned about the water breaking during the trip or leaking if it has already broken. A towel can be placed on the seat to catch any fluid or mom can wear a maxi-pad.
Know where to park, where to enter and if you need to alert anyone that you're coming or if you should just show up. Also knowing the routines like whether you'll go straight into a room for birth or if you will be required to stay in a triage area to assess your labor first will help make a more smooth transition to the place of birth.
A word to the wise about driving: go slowly and safely. If you're concerned that she's having the baby pull over, do not try to speed and endanger yourself. She will probably be very uncomfortable in the car and every bump will increase her discomfort. Do what you can to make it a safe and comfortable car trip.