How to time contractions

Measure duration and frequency the way care teams ask for it: frequency from the start of one contraction to the start of the next.

Two numbers describe contractions: how long each one lasts (duration) and how often they come (frequency). Frequency is measured from the start of one contraction to the start of the next, not from the end of one to the start of the next. Mixing the two is the most common timing mistake.

Step by step

1. Start the timer when the tightening begins.
2. Stop it when the contraction eases. That is the duration.
3. Start again with the next one. The time between the two starts is the interval.
4. Time several in a row. One interval does not show a pattern; an hour of timings does.
5. Write down anything else your care team may ask about: your waters, bleeding, and how your baby is moving.

What a pattern looks like

Labor contractions usually come in a regular pattern and get closer together over time. Practice contractions can be strong too, but they are often irregular and may ease with rest or a change of position (ACOG). A timer shows the pattern; it cannot tell you whether labor has started.

When to call

Your midwife or doctor tells you when to call. The NHS advises calling your midwife or maternity unit if you think labor has started or you have regular contractions every 5 minutes or more often, and calling urgently if your waters break, you have vaginal bleeding, your baby is moving less than usual, you are less than 37 weeks pregnant, a contraction lasts longer than 2 minutes, or you have 6 or more contractions in 10 minutes (NHS). Call whenever you are worried.

Timing with Birthtide

Birthtide has one large Start/Stop button you can use without looking, measures frequency start to start and shows duration separately. Every tap is saved on your iPhone at once, so records survive the app closing or the phone restarting. A Live Activity keeps the timer on the Lock Screen. You choose a rule (5-1-1, 4-1-1, 3-1-1 or your own) and Birthtide shows when your timings match it; it never tells you whether labor has started.

General information, not medical advice. Written by the developer of Birthtide; follow the advice of your midwife or doctor. Checked 29 October 2026.

Sources

• ACOG — How to tell when labor begins
• NHS — Signs that labour has begun

Other guides

• The 5-1-1 rule for contractionsWhat 5-1-1, 4-1-1 and 3-1-1 mean, how to check them with a timer, and why your care team’s advice comes first.
• Baby movements and kick countingGet to know your baby’s usual pattern, how a kick count works if your care team asks for one, and when to call straight away.
• How to choose a contraction timer appNine things to check before labor: start-to-start timing, one-handed use, saving offline, no pop-ups, privacy, a rule you choose, reports for your midwife and the price.