Potter syndrome is a fatal condition in which a baby develops physical abnormalities in the womb because of severely low amniotic fluid, a condition called oligohydramnios. The central problem is almost always related to the kidneys: when a fetus’s kidneys are missing or not working, they cannot produce urine, and urine is the primary source of amniotic fluid during pregnancy. Without enough fluid surrounding the baby, the walls of the uterus compress the fetus, restricting movement and distorting how the face, limbs, and lungs develop.
The terms “Potter syndrome” and “Potter sequence” are often used interchangeably. Technically, Potter sequence is the broader term, describing the chain of events that follows low amniotic fluid regardless of the cause. Potter syndrome refers more narrowly to cases caused by the kidneys failing to form (bilateral renal agenesis). In practice, the distinction rarely matters outside of medical literature.
How Low Amniotic Fluid Causes the Problem
During a normal pregnancy, the fetus constantly swallows amniotic fluid and replaces it by urinating. This cycle keeps fluid levels stable. When the kidneys are absent, severely underdeveloped, or blocked, the fetus cannot produce urine, so the fluid level drops steadily as the pregnancy progresses. By the second trimester, amniotic fluid volume can become critically low.
Amniotic fluid does more than cushion the baby. It gives the fetus room to move, which is essential for normal bone and joint development. It also plays a direct role in lung growth. The fetus “breathes” amniotic fluid in and out of its developing lungs, and the fluid supplies a building-block amino acid (proline) that lung tissue needs. Without it, the lungs remain small and underdeveloped, a condition called pulmonary hypoplasia. At the same time, the uterine wall presses against the baby’s chest and abdomen, preventing the rib cage from expanding enough for the lungs to grow. This combination of missing fluid and physical compression is what makes the lung problems so severe and, ultimately, what makes the condition fatal in most cases.
What Causes It
The most common cause is bilateral renal agenesis, meaning both kidneys simply never form. Other kidney-related causes include severely underdeveloped kidneys (renal hypoplasia), polycystic kidney disease present from birth, and physical blockages in the urinary tract that prevent urine from reaching the amniotic sac.
Not every case originates with the kidneys. Premature rupture of membranes, where the fluid-filled sac surrounding the baby breaks too early, can also drain enough amniotic fluid to trigger the same sequence of compression and underdeveloped lungs. In these cases, the kidneys themselves may be perfectly normal, but the outcome for the baby can be similar depending on how early the rupture occurs and how much fluid is lost.
Physical Features at Birth
Babies born with Potter syndrome have a recognizable set of physical characteristics, sometimes called “Potter facies.” These include a flattened nose, a recessed chin, prominent skin folds at the inner corners of the eyes, and low-set ears with unusually wide outer ear cartilage. These features result directly from the baby being compressed in the uterus without the normal cushion of fluid.
Beyond the face, skeletal and limb abnormalities are common. Clubfoot, shortened limbs, displaced toes, and spinal malformations such as fused or misshapen vertebrae can all occur. Some affected babies also have underdeveloped genitalia or an absent anal opening. The severity varies depending on how early in pregnancy the amniotic fluid dropped and how low it went.
How It Is Detected
Potter syndrome is typically identified during a routine prenatal ultrasound. The two key findings are very low or absent amniotic fluid and kidneys that are missing, abnormally small, or visibly cystic. Ultrasound can also show an empty fetal bladder, which strongly suggests the baby is not producing urine. When these signs appear together in the second trimester, the diagnosis is usually straightforward. In cases where the kidneys appear normal on imaging, further investigation into possible urinary obstruction or membrane rupture follows.
Prognosis and Survival
Potter syndrome caused by bilateral renal agenesis has historically been considered universally fatal. The immediate cause of death is the severe lung underdevelopment: even with intensive care at birth, the lungs are too small to support breathing. Most affected babies are stillborn or die within hours of delivery.
A recent experimental approach has offered a narrow window of hope. A clinical trial published in JAMA tested serial amnioinfusions, a procedure where saline is injected into the uterus multiple times during pregnancy to temporarily replace the missing amniotic fluid and give the lungs a chance to grow. Among 18 pregnancies treated, 17 resulted in live births (94%), and 14 of those 17 babies (82%) survived long enough to breathe on their own in the first weeks of life. However, the picture grew more difficult after that: only 6 of the 17 live-born infants (35%) survived to leave the hospital. Those survivors required dialysis starting around six months of age, and the trial was stopped early due to concerns about the burden of complications beyond lung function.
These results show that the lung problem can potentially be addressed, but the absence of kidneys creates a second, independent survival challenge. Even when the lungs develop enough to function, the baby still has no kidney function and needs dialysis as a bridge to an eventual transplant, a path that carries significant risk for a newborn.
The Role of Genetics
Whether Potter syndrome has a genetic component depends on the underlying cause. Bilateral renal agenesis can occur sporadically with no family history, but it can also run in families. When it does, the inheritance pattern varies and may involve mutations in several different genes that guide kidney development.
Some of the kidney diseases that lead to Potter syndrome are clearly inherited. Autosomal recessive polycystic kidney disease, for example, requires both parents to carry a copy of the affected gene, giving each pregnancy a 1-in-4 chance of producing an affected child. For families who have had one pregnancy affected by Potter syndrome, genetic counseling can help clarify the specific cause and estimate the risk of recurrence in future pregnancies.