Labor contractions are the periodic tightening and relaxing of the uterine muscle, the largest muscle in a woman's body. Contractions decrease in duration and increase in frequency as labor draws closer.

Start timing when you feel a few contractions in a row that seem to be following a regular pattern so you can determine whether you're going into labor.

This application will show you the length and the frequency of your contractions. The length will be measured from the beginning of one contraction to the end of the same contraction. The frequency (how far the contractions are apart) will be calculated from the beginning of one contraction to the beginning of the next one.

Contact your physician when your contractions are regular and strong. For example, some consider a 5-1-1 mnemonic, when contractions regularly come five minutes apart, each one lasts one minute, with this pattern continuing for an hour. For measuring contraction strength, some describe it as having the following characteristics: they can walk and talk through the contraction, can hardly walk and talk, have to stop and wait for the contraction to be over, can hardly bear the contraction.