Polyhydramnios in the third trimester: what to know

Amniotic fluid cushions the baby and allows movement. A higher fluid level may be mild, moderate or marked, and an ultrasound finding does not by itself identify the cause. Your maternity team may review your pregnancy history, check the baby’s growth and look for conditions that can influence fluid levels. Sometimes no clear reason is found. Extra fluid can stretch the uterus and make breathlessness, reflux or abdominal tightness more noticeable. It can also affect how the baby is positioned, so late-pregnancy planning may need extra attention.

Keep the follow-up appointments arranged by your obstetric team. Monitoring may include repeat ultrasound, checks of growth and assessment of the baby’s wellbeing. Tell the team about worsening breathlessness, rapid abdominal enlargement, contractions or reduced movement. Do not change prescribed medicines or restrict fluids on your own. A growth scan can help your clinician assess fetal size and fluid alongside the wider pregnancy picture.

Contact your maternity unit promptly if your waters break, you have regular painful contractions, vaginal bleeding, severe abdominal pain or noticeably reduced fetal movement. Seek urgent help for breathing difficulty at rest, faintness or sudden severe swelling. These symptoms need assessment because they can signal an obstetric problem, whether or not polyhydramnios is the cause.

Ask what the fluid finding means in your case, whether the baby’s growth and position are reassuring, how often monitoring is needed, and what symptoms should prompt a same-day call. You can also ask how the finding may influence the timing and place of birth.