What should you know about polyhydramnios and birth defects?

A fetus normally swallows amniotic fluid and later passes urine. If swallowing is reduced, fluid can build up; other fetal, placental or maternal factors can also affect the level. Ultrasound may therefore review the brain, spine, heart, stomach, kidneys, limbs, growth and movement. The scan may be reassuring, may identify a feature needing specialist review, or may not show a clear explanation.

Ultrasound cannot answer every question, and visibility can be affected by fetal position, pregnancy stage and the amount of fluid. An uncertain finding is not the same as a diagnosis.

Attend the recommended detailed ultrasound or repeat assessment. Your team may monitor fluid, growth and fetal movement, review diabetes testing and arrange specialist imaging when a particular concern needs closer examination. A growth scan can support ongoing assessment.

Write down what the scan showed and which findings are confirmed, uncertain or still being checked. Ask what result would change the follow-up plan and when you will receive an explanation.

Contact maternity care urgently for reduced fetal movement, vaginal bleeding, leaking fluid, regular contractions, severe abdominal pain or severe breathlessness. These symptoms require assessment independently of whether an ultrasound found a possible anomaly.

Ask which anatomical areas were clearly seen, whether any finding needs specialist review, whether genetic counselling or another test is being offered, and when the next scan is due. Ask what the fluid level means for your individual pregnancy.