When is too much amniotic fluid harmful during pregnancy?
Polyhydramnios is a medical condition in pregnant women where an excess of amniotic fluid occurs in the amniotic sac. This extra amniotic fluid is not uncommon in pregnancies and can occur for unknown, often harmless, reasons. However, in some pregnancies, the excess amniotic fluid can signal gestational diabetes, chromosomal anomalies or other medical conditions in the fetus.
When the excess fluid occurs, it is because the fetus is unable to swallow it, therefore the mother retains this fluid. The fetus' inability to swallow could be for several reasons such as an esophagus or neurological cause. It could also indicate a craniofacial condition, where the fetus has a very small jaw and normal swallowing cannot be achieved. The medical term for this small jaw is called micrognathia. Pierre Robin Sequence (PRS), Goldenhar syndrome (GS), Bilateral Hemifacial (B-HFM), Nager/Miller syndromes and Treacher Collins syndrome (TCS) are just some of the craniofacial conditions known to cause micrognathia.
In observing Treacher Collins syndrome for example, many mothers who delivered babies with moderate to severe TCS reported high levels of amniotic fluid throughout pregnancy. Often these mothers complained to their obstetricians (OBGYN) that something didn't feel right; that the extra fluid and immense swelling made them miserable. Some even had the fluid drained to alleviate the misery. Unfortunately, much of the time their obstetricians did not refer them to a specialist experienced in finding causes for the polyhydramnios through ultrasound and other testing.
Maternal Fetal Medicine (MFM) specialists, as they are called, are trained to look for certain criteria to find answers. If they suspect a craniofacial occurrence, or want to rule it out, they will attempt to look at the fetus's profile in ultrasound to determine if micrognathia could be indicated. They will also attempt to look at the ears as well as try to determine if a cleft lip and/or cleft palate is present. Since a cleft palate cannot always be detected in ultrasound, an abnormal uvula, which usually can be seen could indicate a cleft palate. Specialists look at all the factors in attempting to determine a cause for the excess amniotic fluid. Even if a condition is present, sometimes it cannot be determined in testing and the baby may not be diagnosed until after birth. It is important to note that statistics show only three percent of polyhydramnios cases result in craniofacial births; however, many positive cases go unreported, therefore the number could be higher.
Even with the low probability of an issue, it is recommended that any pregnant mother who begins to retain excess amniotic fluid during her pregnancy should be seen by a MFM specialist to determine any causes and prepare families for possible medical complications, if any, before the birth occurs. This creates awareness and enables the family, doctor and the delivering facility to take precautions if needed.
Judy Mosher | Craniofacial Program Specialist
