Oligohydramnios, causes and symptoms

Oligohydramnios: what is it

Oligohydramnios is when there is too little amniotic fluid.

A deficient volume of amniotic fluid, a condition that can occur in


Oligohydramnios is a very serious problem, but it is also a relatively rare problem. According to some estimates made in America, it is present in only 4-12% of pregnancies and post-term pregnancies are more at risk of developing it.


This condition manifests itself during pregnancy when,

  • the Amniotic Fluid Index (AFI) measured by ultrasonography, is less than 5 cm (normally measuring between 5 and 25 cm),
  • and when the maximum pocket size is less than 2 cm (normally it measures between 2 and 8 cm).
  • An experienced sonographer is able to detect this condition by eye, without having to resort to the above measurements.


The volume of fluid that surrounds the baby during the nine months is determined by the amount of fluid flowing into and from the amniotic sac. It is a dynamic equilibrium.

Rupture of membranes is the most common cause of oligohydramnios. Other possible causes are placental infarction or thrombosis, utero-placental insufficiency and twin to twin transfusion syndrome (TTTS).

Instead, they are related to the fetus, the absence of urine production, a blockage in the urinary tract, chromosomal abnormalities (eg Down syndrome), abnormalities that cause swallowing problems, congenital anomalies that involve a reduction in urine production, problems related to the growth of the fetus or death of the same.

Among the causes related to the mother we find the following conditions:

  • previous pregnancies with limited growth,
  • chronic hypertension,
  • preeclampsia,
  • diabetes
  • systemic lupus erythematosus (SLE),
  • multiple pregnancies,
  • birth defects, such as kidney abnormalities,
  • post-term pregnancy,
  • idiopathic diseases,


Oligohydramnios is a problem that can occur during any trimester of pregnancy, but during the first 6 months it is more worrisome. In that period it involves greater risks of: birth defects, termination of pregnancy, preterm birth, loss of neonatal life.

When liquid levels are low in the last quarter, the related risks include:

  • slow fetal growth,
  • complications of labor,
  • the need for a cesarean delivery.

The evolution of a pregnancy in the presence of oligohydramnios is carefully monitored in order to ensure the normal development of the fetus. In some cases, to protect the mother or baby, doctors may assess the need to induce labor. It may also be necessary: an amnioinfusion (infusion of saline in the uterus), increased maternal fluids, bed rest.

In case of oligohydramnios, Adue to the risk of umbilical cord compression, there is an increased chance of complications of labor, during which an amnioinfusion may be necessary by inserting a physiological solution into the amniotic sac. In some cases, may be necessary.

Katherine Johnson, M.D., is a board-certified obstetrician-gynecologist with clinical expertise in general obstetrics and gynecology, family planning, women’s health, and gynecology.

She is affiliated with the Obstetrics and Gynecology division at an undisclosed healthcare institution and the online platform, Maternicity.com.

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