What causes oligohydramnios (low amniotic fluid)?

Mar 21, 2025 Source: Cainiu Health

Dr. Zhang Lu

Introduction

In general, oligohydramnios (low amniotic fluid) may be caused by individual variations, insufficient maternal hydration, post-term pregnancy, gestational hypertension, premature rupture of membranes, and other factors. Symptomatic management may involve general treatment, pharmacological treatment, or surgical intervention. In daily life, pregnant women are advised to rest adequately, avoid excessive fatigue, and undergo regular prenatal examinations to monitor fetal and placental conditions.

Generally, oligohydramnios (low amniotic fluid) may be caused by individual differences, insufficient maternal water intake, post-term pregnancy, gestational hypertension, premature rupture of membranes, and other factors. Symptomatic management may involve general treatment, medication, or surgical interventions. If physical discomfort occurs, prompt medical evaluation and treatment at a hospital are recommended. Detailed explanations are as follows:

1. Individual Differences

There may be individual variations in the volume of amniotic fluid among pregnant women. Some women may naturally have lower levels of amniotic fluid, typically without significant associated symptoms. Changes in amniotic fluid volume may only be detected during routine prenatal examinations. Close monitoring and regular ultrasound scans are recommended to ensure normal fetal growth and development.

2. Insufficient Maternal Water Intake

Inadequate daily water intake in pregnant women can lead to increased plasma osmotic pressure, which similarly affects the fetus. This results in increased absorption of amniotic fluid by the placenta and greater water absorption in the fetal renal tubules, ultimately reducing urine production and leading to oligohydramnios. Pregnant women should increase their water intake to maintain adequate hydration, which may help improve amniotic fluid levels.

3. Post-Term Pregnancy

Pregnancy extending beyond 42 weeks is termed post-term pregnancy. At this stage, placental function may gradually decline, leading to decreased amniotic fluid production. This condition typically does not present with other symptoms but may increase the risk of fetal hypoxia or distress. Doctors may recommend termination of pregnancy through labor induction or cesarean section to ensure fetal safety.

4. Gestational Hypertension

Pregnant women with a family history of hypertension or abnormal placental implantation may develop gestational hypertension. This condition can impair placental function, affecting fetal blood volume and urine production, ultimately resulting in oligohydramnios. Symptoms may include hypertension, proteinuria, and edema. Pregnant women are advised to take medications such as labetalol hydrochloride tablets, nifedipine tablets, or methyldopa tablets under medical guidance.

5. Premature Rupture of Membranes

Premature rupture of membranes leads to leakage of amniotic fluid from the amniotic cavity. The rate of amniotic fluid production may not keep up with the loss, resulting in oligohydramnios. Pregnant women may suddenly feel fluid leaking from the vagina, sometimes accompanied by abdominal pain or vaginal bleeding. Depending on the specific situation, doctors may recommend either termination of pregnancy or conservative management if oligohydramnios occurs alongside premature rupture of membranes.

In daily life, pregnant women should ensure adequate rest, avoid excessive fatigue, and undergo regular prenatal check-ups to monitor fetal and placental conditions.

References

[1] Zhang Yijin. What to Do When Amniotic Fluid Is Low [J]. Family Medicine. Happy Health, 2020, (09): 63.

[2] Chang Xiangfen. Understanding Amniotic Fluid During Pregnancy [J]. Chinese Journal of Family Planning, 2019, 27(09): 1264.

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