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What Causes Maternal Hydronephrosis?

About Hydronephrosis In Pregnancy

Hydronephrosis during pregnancy is quite a common condition in many pregnant females. The development of Hydronephrosis during pregnancy is termed as Maternal Hydronephrosis. It is basically caused by the dilation of the renal pelvis and some part of the upper portion of the uterus while the female is pregnant. Urinary tract infection which is quite common in pregnant females is believed to increase the risk of a pregnant female developing Maternal Hydronephrosis.

Thus, Maternal Hydronephrosis affects almost all pregnant females during their gestation period especially in the second and third trimester when the weight of the fetus causes dilation of the uterus. It is estimated that about 90% of dilations of uterus happens on the left side and very rarely the right side gets affected.

Hydronephrosis caused due to any other condition like an obstruction in the ureters tends to worsen the condition of Maternal Hydronephrosis. In some cases Maternal Hydronephrosis may be completely asymptomatic; however, in most cases a female with Maternal Hydronephrosis will exhibit flank pain around the abdominal region, persistent nausea and vomiting, pain with urination, hematuria in some cases where the female has a case of severe urinary tract infection.

Edema of the lower extremities is also seen in females along with increased urinary frequency and urgency in females with Maternal Hydronephrosis. Some of the probable causes of Maternal Hydronephrosis have been discussed above but delineated below are the exact causes of Maternal Hydronephrosis.

What Causes Maternal Hydronephrosis?

What Causes Maternal Hydronephrosis?

During pregnancy, a female undergoes significant hormonal changes to include estrogen, progesterone, and prostaglandin. These hormonal changes tend to cause Maternal Hydronephrosis. Additionally, during pregnancy, the smooth muscles of the body are relaxed as a result of changes in hormone progesterone. This also tends to cause Maternal Hydronephrosis.

As mentioned above, as the female enters the second and third trimester of pregnancy the increasing weight of the fetus causes the uterus to dilate and cause Maternal Hydronephrosis. The renal blood flow is almost doubled in pregnant females and so is the glomerular filtration rate. This also increases the chances of a female having Hydronephrosis in pregnancy.

In addition to the above causes, kidney stones, urinary tract infections, blood clots in the ureters, urethral strictures and in some rare cases bladder cancer may also increase the incidences of a female having Maternal Hydronephrosis or Hydronephrosis during pregnancy.

Obese and diabetic females are also at risk for Maternal Hydronephrosis if they do not keep their weight in check and blood sugar in control which are of paramount importance in order to prevent a condition like hydronephrosis during pregnancy.


  1. Canadian Urological Association Journal. (2016). Hydronephrosis in pregnancy: Impact on maternal and fetal outcomes. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4873785/
  2. National Institute of Diabetes and Digestive and Kidney Diseases. (2021). Urinary Tract Infections in Adults. https://www.niddk.nih.gov/health-information/urologic-diseases/urinary-tract-infections-adults
  3. The American College of Obstetricians and Gynecologists. (2020). Prenatal Development: How Your Baby Grows During Pregnancy. https://www.acog.org/womens-health/faqs/prenatal-development-how-your-baby-grows-during-pregnancy

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Team PainAssist
Team PainAssist
Written, Edited or Reviewed By: Team PainAssist, Pain Assist Inc. This article does not provide medical advice. See disclaimer
Last Modified On:August 3, 2023

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