Amniotic Fluid: What’s in It, What Affects It, and Why It Matters

ByHemali Ramchandani
Updated: 23 Jun 2025, 9:34 am

Amniotic fluid isn’t just a cushion. It’s a dynamic, life-sustaining substance that protects your baby, supports organ development, and reflects your pregnancy health. Its quantity and quality can indicate everything from gestational age to potential complications like oligohydramnios or infections. Understanding what amniotic fluid does, what can go wrong, and how it’s monitored empowers you to spot concerns early and take action when needed.

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You might only notice the term “amniotic fluid” during an ultrasound report or a conversation about your baby’s movements. But this clear, slightly yellow liquid does far more than just surround your baby; it’s crucial to every stage of development. It regulates temperature, cushions the fetus, supports lung and digestive development, and even allows for safe movement inside the womb.

In this article:


When the levels are too low or too high, or when the fluid becomes infected or leaks prematurely, it may signal a problem that requires closer monitoring or medical intervention. This article walks you through what’s normal, what’s not, and what steps you can take to protect your health and your baby’s development.


What Is Amniotic Fluid?

Amniotic fluid is the protective liquid held within the amniotic sac, surrounding the fetus throughout pregnancy. It begins forming around 12 days after conception and is initially made up of water from the mother’s body. By the second trimester, most of the fluid is made up of fetal urine and lung secretions.

Healthy amniotic fluid:

  • It is clear to pale yellow
  • Has a slightly earthy smell
  • Contains proteins, electrolytes, fetal cells, hormones, and nutrients
Over time, your baby swallows the fluid and urinates it out, maintaining a constant cycle that supports lung development, gastrointestinal maturation, and muscle tone.


Why Amniotic Fluid Matters

While it might seem passive, amniotic fluid actively supports your baby’s growth and protects both of you from complications.

  • Cushions the fetus: Protects against external pressure or trauma by acting as a shock absorber.
  • Enables movement: Helps develop muscles and bones by allowing the baby to move freely.
  • Promotes lung and digestive development: Inhalation and swallowing of fluid are essential for organ maturation.
  • Prevents umbilical cord compression: Maintains space so that the cord doesn’t get squeezed, protecting oxygen flow.
  • Maintains temperature: Acts as a thermal buffer, keeping the baby warm and regulating body temperature.
  • Protects from infection: It contains antimicrobial peptides and acts as a barrier from external pathogens.
Changes in fluid volume or composition often reflect how well the pregnancy is progressing.



Causes of Abnormal Amniotic Fluid Levels

Changes in the amniotic fluid levels tell us a lot about the health of the foetus as well as the mother:

Too little fluid (Oligohydramnios):

  • Rupture of membranes (slow leaks or sudden gush)
  • Placental insufficiency
  • Post-term pregnancy (beyond 41 weeks)
  • Fetal kidney or urinary tract problems
  • Certain medications (NSAIDs, ACE inhibitors)
Too much fluid (Polyhydramnios):

  • Uncontrolled gestational diabetes
  • Fetal swallowing difficulties (e.g., anencephaly, oesophageal atresia)
  • Twin-to-twin transfusion syndrome (in monochorionic twins)
  • Maternal infections or fetal anomalies
Abnormal colour or odour:

  • Greenish fluid suggests meconium (baby’s first stool), and is a sign of fetal distress.
  • Cloudy or foul-smelling fluid may indicate infection, such as chorioamnionitis.


How Amniotic Fluid Is Measured

Obstetricians use ultrasounds to estimate amniotic fluid levels through two main methods:

  • Amniotic Fluid Index (AFI): Measures fluid in four quadrants of the uterus. A normal AFI ranges from 8 to 18 cm. Less than 5 cm suggests oligohydramnios, while more than 24 cm suggests polyhydramnios.
  • Single Deepest Pocket (SDP): Looks for the deepest visible pocket of fluid without fetal parts or cord. The ideal range is 2–8 cm.
These tests may be part of a ‘Biophysical Profile’ (BPP) if fetal distress is suspected. Regular monitoring is recommended for high-risk pregnancies, especially those with diabetes, hypertension, or previous complications.


Managing Amniotic Fluid Concerns

Depending on whether fluid levels are too high or too low, your doctor may suggest:

  • Hydration: Drinking more water can sometimes improve fluid levels.
  • Treating underlying causes: Managing gestational diabetes or infections can restore balance.
  • Bed rest or positioning: May help in cases of cord compression or low fluid.
  • Amnioinfusion: In labour, saline or lactated Ringer’s solution is introduced into the uterus to dilute meconium-stained fluid or relieve cord compression.
  • Early delivery: In severe cases of fluid imbalance, induction or caesarean may be considered if the baby is mature enough.
Always follow your obstetrician’s guidance, especially if you notice a sudden change in fetal movement or symptoms like leaking fluid.


Emotional and Practical Support

Discovering abnormal fluid levels can feel frightening, especially when test results change week to week. During this time:

  • Seek clarity from your care team: Don’t hesitate to ask what the numbers mean and what your options are.
  • Practice gentle hydration habits: Carry a water bottle, set hourly reminders, and opt for hydrating foods like fruits and soups.
  • Prepare for medical interventions: If you’re told you may need early delivery or close monitoring, take time to mentally and practically plan for that shift.
  • Connect with support groups: Online communities or local antenatal classes often include others navigating similar concerns.
  • Allow space for your feelings: It’s normal to worry. You’re not failing your baby. You’re learning how to respond with awareness and care.
Amniotic fluid is more than just “water around the baby.” It’s a diagnostic tool, a developmental support, and a key indicator of maternal and fetal health. By understanding what influences its levels and what symptoms to watch for, you’re taking a proactive step toward safer, more informed pregnancy care. Trust your instincts, ask questions, and know that support is always within reach.

FAQs on Amniotic Fluid: What’s in It, What Affects It, and Why It Matters

  1. Can I increase amniotic fluid by drinking more water?
    In some cases, yes. Staying hydrated can help raise low fluid levels, especially in the third trimester.
  2. Is it dangerous if my water breaks early?
    Premature rupture of membranes can increase infection risk. Seek immediate medical attention if you suspect it.
  3. What does meconium-stained fluid mean?
    It may suggest that the baby is under stress. Your doctor will monitor you closely or may recommend delivery if needed.
  4. Can polyhydramnios harm the baby?
    Mild cases often resolve on their own, but severe cases can increase the risk of preterm labour or umbilical cord issues.
Disclaimer: Medically approved by Dr Sahana K P, Consultant - Obstetrics and Gynaecology, Apollo Hospitals

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