Why is polyhydramnios common in twin pregnancies?
Apr 18, 2023
Source: Cainiu Health
Dr. Lv Aiming
Introduction
Twin pregnancies are prone to twin-to-twin transfusion syndrome, in which the recipient twin experiences increased circulating blood volume, leading to elevated fetal urine output and consequently polyhydramnios. Maternal hyperglycemia causes fetal hyperglycemia, resulting in osmotic diuresis that increases exudation from the placenta and fetal membranes. Additionally, when the fetus has neural tube defects, excessive production of amniotic fluid combined with significantly reduced fetal swallowing can also contribute to polyhydramnios.
Twins refer to a twin pregnancy. Polyhydramnios in twin pregnancies is mostly caused by physiological and pathological factors, with pathological causes often associated with gestational diabetes and fetal malformations. When polyhydramnios occurs, it is important to promptly visit the obstetrics department of a hospital to identify the underlying cause and receive timely treatment if abnormalities are found. Specific analyses are as follows:
I. Physiological Causes
Twin pregnancies are prone to twin-to-twin transfusion syndrome (TTTS). In the recipient twin, increased blood volume leads to elevated fetal urine production, which in turn causes polyhydramnios. This condition usually does not require special intervention.
II. Pathological Causes
1. Gestational Diabetes
When a pregnant woman has gestational diabetes, the fetus experiences elevated blood glucose levels due to maternal hyperglycemia, resulting in osmotic diuresis. This increases fluid exudation from the placenta and fetal membranes, leading to polyhydramnios. Treatment typically involves medications such as metformin hydrochloride tablets, acarbose tablets, or insulin aspart injection under medical supervision. Once blood glucose levels normalize, amniotic fluid volume usually returns to normal.
2. Fetal Malformations
Fetal neural tube defects or other developmental abnormalities of the brain and nervous system may lead to insufficient secretion of antidiuretic hormone, causing excessive production of amniotic fluid. Additionally, significantly reduced fetal swallowing contributes to the accumulation of amniotic fluid. If severe fetal malformations are diagnosed, termination of pregnancy may be necessary.
In addition, conditions such as fetal hydrops may also cause polyhydramnios. A low-salt diet is recommended, and prompt evaluation and treatment at the obstetrics department of a hospital are essential to determine the specific cause of excess amniotic fluid.
