Active labor lasts an average of four to six hours. This is quite possibly the time when your care provider will want you to go to the hospital or birth center. When to begin traveling to the hospital depends on if this is your first baby, road conditions, time of day and how far apart the contractions are and how long they have been consistently this long and far apart. Contractions during the active phase are generally three to four minutes apart and last about 40 to 60 seconds.

The cervix dilates from 4 to 7 centimeters and the contractions begin to increase in intensity as the baby puts more pressure on your cervix. You may experience more bloody show as the baby presses downward farther. Dealing with the increasing intense and longer contractions can produce anxiety and exhaustion. You will really appreciate the support, both physical and emotional, that you receive from your partner now.

During the active phase, you may also notice increased back discomfort. It is usually during this time that you have true back labor. The pelvis is shaped so that the ideal way for the baby to pass through is that the face of the baby faces your back and the top of the head or crown slides under the pubic bone. This is called being "anterior" in position. Occasionally, babies begin their descent through the pelvic bones "face up" or posterior in position. Being posterior, and having the crown of the baby's head pressing on the tailbone produces a great deal of pressure type pain.

Your childbirth educator probably taught you how to do the pelvic rock. Pulling the baby into the sling that the tummy muscles make (by being on all fours) and rotating your pelvis, may cause the baby to turn from posterior to anterior. Your labor nurse will be able to tell you if the baby is anterior or posterior after a vaginal exam - depending on which soft spot is on top at the time of the exam.

References:

1. Bobak, I., Jensen, M. Maternity & Gynecologic Care: The Nurse and the Family. (1989) St. Louis: Mosby Publishers.
2. Nichols, F., Humenick, S. Childbirth Education: Practice, Research & Theory (2000) Saunders & Co.
3. Whitely, N. A Manual of Clinical Obstetrics (1985) Philadelphia: J.B. Lippincott Company.
4. Reeder, S., Martin, L., and Koniak-Griffin, D. Maternity Nursing: Family, Newborn, and Women's Health Care. (1997) Philadelphia: J.B. Lippincott Company.