Polyhydramnios Statistics
Polyhydramnios is a rare condition that complicates about 1% of all pregnancies. This page breaks down many of the known statistics surrounding it.
Table of Contents
Statistics
Severity of Polyhydramnios
- 65-70% – mild (SDP 8-11 cm or AFI 24-30 cm)
- 20% – moderate (SDP 12-15 cm or AFI 30.1-35 cm)
- 10-15% – severe (SDP 16 cm + or AFI 35.1 cm +)
Frequency of Polyhydramnios
According to a 2018 OB-GYN Workforce Study in the United States, “nationally, there are – on average – 100 births per OB-GYN annually.”
That means, that the average OB-GYN in the United States sees
- 1 mild case of Polyhydramnios every year
- 1 moderate case of Polyhydramnios every 4 years
- 1 severe case of Polyhydramnios every 6 years
- 2 mild cases of Polyhydramnios every year
- 1 moderate case of Polyhydramnios every other year
- 1 severe case of Polyhydramnios every 3 years
How Common is Idiopathic Polyhydramnios?
Idiopathic refers to “any disease that is of uncertain or unknown origin.”
- Of mild cases, 83% have an unknown origin
- Of moderate/severe cases 9% have an unknown origin
- 57-60% of all cases of Polyhydramnios are considered idiopathic at the time of delivery
- Mild cases are much more likely to be idiopathic and result in uncomplicated deliveries of healthy babies
- The more severe the Polyhydramnios is the more likely a woman is to experience complications during delivery and with her baby.
What Causes Polyhydramnios?
Only 40-43% of cases of polyhydramnios have an identifiable cause before delivery. Out of those cases, these are the statistics for the origin:
- 45% – genetic anomaly (~18% of all Polyhydramnios cases)
- 25.5% – other conditions, such as infection or blood incompatibility (~10% of all Polyhydramnios cases)
- 11% – fetal anemia (~4% of all Polyhydramnios cases)
- 10% – complications of multiple pregnancies (~4% of all Polyhydramnios cases)
- 8.5% – maternal diabetes (~3% of all Polyhydramnios cases)
Rates of Adverse Outcomes in Labor and Delivery with Polyhydramnios
- Rate of induction is 7.9% (vs. normal pregnancies: 4.8%)
- Rate of c-section is 12.1% (vs. normal pregnancies: 5.1%)
- Rate of placental abruption is 0.9% (vs. normal pregnancies: 0.2%)
- Rate of abnormal fetal heart rate is 7% (vs. normal pregnancies: 3.2%)
- Rate of prolonged first stage of delivery is 6% (vs. normal pregnancies: 1.4%)
- Rate of shoulder dystocia is 1.9% (vs. normal pregnancies: 0.3%)
- Rate of Respiratory Distress Syndrome is 0.5% (vs. normal pregnancies: 0.03%)
- 35-55% of c-section deliveries in Polyhydramnios are due to failure to progress
Umbilical Cord Prolapse (UCP) with Polyhydramnios
- 3.57 times more likely to be pregnant with multiples
- 4.67 times more likely to have a non-vertex presentation
- 2.28 times more likely to have preterm labor
- 3.84 times more likely to have PROM
- 12.31 times more likely to have a prolapsed amniotic bag
- 2.89 times more likely to have Polyhydramnios
- 2.26 times more likely to have a birth weight <2500 grams
- 9% of all pregnancies have SROM, 1.9% of these experience UCP
- 4.3% of all deliveries are breech, 2.5-7.5% of these experience UCP
- 4.4% of all deliveries are transverse, 3.8-4.6% of these experience UCP
- 15.3% of all deliveries have a birthweight <2500 grams; 0.9-2.4% of these experience UCP
- 3% when UCP occurs in the hospital
- 44% when UCP occurs outside of the hospital
Other Statistics to Know about Polyhydramnios
- Polyhydramnios increases the risk of late fetal demise
- Polyhydramnios babies have a higher rate of NICU admittance than the normal population
- 9% of cases end up identifying a cause during the immediate neonatal period
- 28% of cases end up identifying the cause within the first year of the baby’s life
FAQs
FAQs
Currently, there are no published studies that link autism to Polyhydramnios. However, autism is linked to some syndromes that are known to cause Polyhydramnios. The best people to ask this question to are the ones who have lived it, so why not check out a Polyhydramnios support group and ask about their experience with this? Check out our list of Polyhydramnios support groups here.
Polyhydramnios has been associated with several anomalies both in women and infants. At the time of delivery, 61% of Polyhydramnios cases are idiopathic, 18% are attributed to a genetic anomaly, 10% to infection or blood incompatibility, 4% to fetal anemia, 4% to Twin to Twin Transfusion, and 3% to gestational diabetes. Additionally, as many as 1/3 of the babies born from an idiopathic Polyhydramnios pregnancy will be diagnosed with a genetic anomaly before their first birthday. Read more about the causes of Polyhydramnios here.
Read Next
Questions for Your Doctor – If you’ve been diagnosed with Polyhydramnios, you probably have a lot of questions. Use our guide to help you get the right ones answered.