Labor contractions are the periodic tightening and relaxing of the uterine muscle, the largest muscle in a woman's body. Something triggers the pituitary gland to release a hormone called oxytocin that stimulates the uterine tightening. It is difficult to predict when true labor contractions will begin. 

Contractions are often described as a cramping or tightening sensation that starts in the back and moves around to the front in a wave-like manner. Others say the contraction feels like pressure in the back. During a contraction, the abdomen becomes hard to the touch. In the childbirth process, the work of labor is done through a series of contractions. These contractions cause the upper part of the uterus (fundus) to tighten and thicken while the cervix and lower portion of the uterus stretch and relax, helping the baby pass from inside the uterus and into the birth canal for delivery.

How Contractions are Timed

Contractions are intermittent, with a valuable rest period for you, your baby, and your uterus following each one. When timing contractions, start counting from the beginning of one contraction to the beginning of the next. 

The easiest way to time contractions is to write down on paper the time each contraction starts and its duration, or count the seconds the actual contraction lasts, as shown in the example below. Writing down the time and length of the contraction is extremely helpful for describing your contraction pattern to your physician, midwife or hospital labor and delivery personnel.

What Contractions Feel Like

Many mothers describe contractions that occur in early labor as similar to menstrual cramps, or as severe gas pains, which may be confused with flu symptoms or intestinal disorders. Imagine your contractions as looking like a wave. Each contraction will gradually gain in intensity until the contraction peaks, then slowly subside and go away. As your body does the work of labor, it is likely that the time in between contractions will become shorter.

As the strength of each contraction increases, the peaks will come sooner and last longer. There should be some regularity or pattern when timed. Persistent contractions that have no rhythm but are five-to-seven minutes apart or less should be reported to your physician or midwife.

Try to Visualize Contractions as Positive

Think of each contraction as something positive—it is bringing you that much closer to the birth of your baby. Visualize what the contractions are accomplishing, the thinning and opening of the cervix and the pushing of the baby downward. Try to work with your body rather than against it by staying as relaxed as possible during the contractions. 

Typical Length or Duration

A typical labor for a first time mother is eight-to-fourteen hours, and is usually shorter for a second or subsequent birth. For many women, rocking in a chair or swaying during a contraction assists them with this relaxation.