At what cervical dilation do your waters break?

Cervical dilation describes how open the cervix is. Waters breaking means the fluid-filled amniotic sac around the baby has ruptured. These are related parts of labour, but one does not happen at a fixed point in the other.

Fluid may come as a sudden gush or a continuing trickle that you cannot control. Amniotic fluid is often clear or pale, although it can be hard to tell apart from urine or increased vaginal discharge. Contractions may already be happening, may begin later, or may not start straight away.

A clinician can assess whether the membranes have ruptured and check your baby's wellbeing. Cervical dilation can only be established by an appropriate clinical examination; the amount of leaking does not reveal how dilated you are.

Call your maternity unit for advice when you suspect your waters have broken, even if contractions have not started. Note when the leaking began and the fluid's colour and smell. Use a clean sanitary pad, not a tampon, so the fluid can be observed, and follow your team's instructions about attending for assessment.

Avoid putting anything into the vagina while awaiting advice. Continue noticing your baby's usual movements and report any reduction or change immediately.

Contact your maternity unit urgently if the fluid is green, brown, smelly or accompanied by vaginal bleeding; if your baby is moving less than usual; if you have fever, severe pain or feel unwell; or if leaking occurs before thirty-seven weeks of pregnancy. These features need assessment regardless of your contraction pattern or presumed dilation.

Seek emergency help for heavy bleeding, collapse, severe breathing difficulty, an urge to push with birth appearing imminent, or another life-threatening concern.

Ask how your team will confirm whether the membranes have ruptured, when they want you to attend, and what symptoms should prompt another call. If labour does not begin, ask how you and your baby will be monitored and which options may be discussed next.