Why does premature rupture of membranes cause waters breaking?

The membranes form a fluid-filled sac around the baby. When the sac weakens or develops a tear, amniotic fluid can trickle or gush through the cervix and vagina. The flow may continue after you change position, unlike ordinary vaginal discharge. Fluid can be clear or pale and may not have a strong smell, but it can be difficult to identify at home. Rupture before labour begins needs prompt assessment because the open sac can change infection risk and the timing of birth decisions.

Use a clean maternity pad to observe the fluid; do not use a tampon or put anything in the vagina. Note when the leakage started, its colour, and whether contractions or reduced movement are present. Contact your maternity unit promptly, even if the leak is small or stops. A clinician may check the fluid and your temperature, assess the baby, and discuss monitoring or treatment based on your stage of pregnancy.

Seek urgent maternity advice for fever, feeling unwell, worsening abdominal pain, regular contractions, vaginal bleeding, green or foul-smelling fluid, or reduced baby movement. Do not wait for a large gush: a persistent damp feeling can also need assessment. Call emergency services if you have heavy bleeding, severe pain, or feel faint.

Ask whether the fluid is amniotic fluid, how your baby will be monitored, which symptoms suggest infection, and what restrictions apply while the membranes are open. You can also ask how to track movements and when to return if leakage changes.