Timing Contractions

The two numbers you are recording

Length (duration) is the time from the moment a contraction starts tightening to the moment it fully releases. Frequency is the time from the start of one contraction to the start of the next — not the gap between them. That distinction is the single most common error, and it matters because every threshold published by the NHS, the HSE and ACOG is expressed start-to-start.

Get it wrong in the other direction and you will underestimate how close together they are: if each contraction lasts 60 seconds and you record a four-minute rest, you will report five minutes apart when timing correctly, and four when timing the gaps. The difference is exactly the size of the threshold everyone is watching for.

When to start timing

Not immediately, and not all night. The HSE gives the trigger: "start timing your contractions when they get stronger or closer together." Before that, timing produces noise rather than information, and it costs you the rest the NHS wants you to take in early labour.

The HSE also caps the effort: "it is helpful to time 3 contractions in a row. Use a watch with a second hand or a mobile phone app." Three in a row gives you an average length and an average frequency, which is what the person on the phone will ask for. It does not require a spreadsheet of the whole night.

What the pattern tells you

A single contraction tells you almost nothing. The pattern across several tells you a great deal.

The NHS describes the direction of travel: "your contractions tend to become longer, stronger and more frequent as your labour progresses." The HSE says the same — "as labour gets going, your contractions usually become longer, stronger and more frequent." Three variables, all moving the same way, is the signature.

ACOG adds two tests you can run without a clock. First, movement: "true labor contractions continue even when you rest or move around", while contractions that stop when you walk, rest or change position are not labour. It suggests explicitly that you "time your contractions and note whether they continue when you are resting and drinking water." Second, location: pain from true contractions "usually starts in the back and moves to the front."

ACOG also gives a typical length for established labour contractions — "each lasts about 60 or 90 seconds" — and notes that they "come at regular intervals. They have a pattern. As time goes on, they get closer together." Practice tightenings, by contrast, have no pattern and do not get closer together.

What it does not tell you

Dilatation. There is no contraction pattern that corresponds reliably to a number of centimetres, which is why NICE's definition of established labour requires both regular contractions and progressive cervical dilatation from 4 cm — the contractions alone are not sufficient to make the call. ACOG says it directly: "sometimes the only way to tell the difference is by having a vaginal exam to find changes in your cervix that signal the start of labor."

The thresholds that trigger a call

The two national health services set these slightly differently, and both are worth knowing.

NHS: call your midwife or maternity unit for guidance if "you're having regular contractions coming every 5 minutes or more often", or simply if you think you are in labour.

HSE: call your midwife when your contractions are regular and "last at least 60 seconds" and "come every 5 minutes." Its non-urgent guidance on going in is "your contractions are 5 minutes apart and are getting stronger."

The HSE adds a practical qualifier that overrides both: "you may need to go to hospital sooner if you live a long distance away." Distance and traffic are a legitimate reason to move earlier, and ACOG suggests rehearsing the journey in advance for exactly this reason.

The patterns that mean call urgently

Timing is not only about knowing when to go in. Two specific patterns are on the NHS urgent list and should prompt an immediate call, day or night:

• Any contraction lasting longer than 2 minutes.
• Six or more contractions every 10 minutes.

These are not arbitrary. In its induction guideline NICE defines uterine hyperstimulation using almost the same numbers — tachysystole as "5 or more contractions per 10 minutes for at least 20 minutes" and hypertonicity as "a contraction lasting at least 2 minutes" — because a uterus contracting too often or for too long can reduce the baby's oxygen supply between contractions.

The rest of the NHS urgent list applies whatever the timings show: waters breaking, vaginal bleeding, the baby moving less than usual, or being under 37 weeks and thinking you might be in labour. The NHS instruction is unambiguous — "do not wait until the next day, call immediately, even if it's the middle of the night."

Call your local emergency number — 999 in the UK and Ireland, 911 in the US and Canada, 000 in Australia, 111 in New Zealand — if you think your baby is coming now and you have a strong urge to push.

When to stop timing

When it stops helping. Once you are in established labour and being cared for, timing is the midwife's job, and NICE expects your contractions to be recorded as part of routine observations in the first stage. Handing the clock over is not giving something up; watching a timer through a contraction actively works against the breathing and relaxation NICE recommends for coping with the pain.

If you have been induced or are on an oxytocin drip, timing is also taken over by continuous monitoring, precisely because the frequency of contractions has to be watched closely.