Polyhydramnios is a rare condition, affecting less than 2% of pregnancies. It occurs when an excess of amniotic fluid is produced during pregnancy. Amniotic fluid is the substance that surrounds the baby in the womb, providing protection and nourishment.
Causes of polyhydramnios
Usually the cause of polyhydramnios is unknown. However, sometimes it can be due to a developmental problem with the baby, indicating a gastrointestinal, respiratory or nervous system disorder. Fortunately, however, these cases are rare. Sometimes the issue is due to an incompatibility between the blood of the mother and the baby, although this is usually avoided by injection with the relevant antibodies early on in pregnancy. Other known causes include multiple pregnancies (twins or triplets) and poorly controlled maternal diabetes.
Symptoms of polyhydramnios
The first symptom of polyhydramnios is more weight gain than would normally be expected during a pregnancy. If your abdomen measurements start falling above the normal range you will likely be referred for additional ultrasound scans, during which, the volume of amniotic fluid will be calculated. An amniotic fluid index (AFI) of greater than 25cm is indicative of polyhydramnios. If this occurs late on in pregnancy, then the effects are likely to be negligible and you will probably just be monitored more closely for the remainder of your pregnancy. If, however, it occurs from an early stage and is more severe, further medical action may be required.
Treatment and consequences of polyhydramnios
The two main treatment approaches are fluid drainage, via amniocentesis, and medication. The drug most commonly used is indomethacin, which reduces the baby’s urine production.
Polyhydramnios frequently leads to early labour and/or a caesarean delivery. It also increases the likelihood of delivering a large baby; babies born to women with polyhydramnios will usually fall into the 90th centile or above.
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- Morris, R K, et al. “Association and Prediction of Amniotic Fluid Measurements for Adverse Pregnancy Outcome: Systematic Review and Meta-Analysis.” BJOG, vol. 121, no. 6, May 2014, pp. 686–699., doi:10.1111/1471-0528.12589.
- Burd, I. “Polyhydramnios.” MedlinePlus, 13 June 2017, medlineplus.gov/ency/article/003267.htm.
- “Polyhydramnios.” Mayo Clinic, 18 Nov. 2017, www.mayoclinic.org/diseases-conditions/polyhydramnios/symptoms-causes/syc-20368493.