Reduced urine output in newborns

Reduced urine output in newborns: An important sign of dehydration

The number of wet diapers per day is one of the most important and objective indicators of a newborn's hydration status. A reduction in urination frequency (oliguria) is the first and most reliable signal that the baby's body has begun to experience fluid deficit and has switched to an "economy mode".

What is happening in the body?

The kidneys are the main organ that regulates water balance. When the body starts losing more fluid than it takes in, special receptors in the brain and blood vessels detect this. In response, antidiuretic hormone (ADH) begins to be produced. This hormone acts on the kidneys, causing them to maximally reabsorb (draw back into the blood) water from the primary urine. As a result, the volume of final urine excreted is significantly reduced, and it becomes more concentrated.

What to watch for?

Normally, after the first few days of life, a newborn should wet at least 6-8 diapers per day. Concerning signs include:

• Dry diaper for 6-8 hours.
• Fewer than 6 wet diapers in 24 hours.
• Very small amount of urine, diaper barely damp.
• Dark, deep yellow urine color with a strong odor.
• Appearance of "brick dust" (uric acid crystals) on the diaper, indicating highly concentrated urine.

Reduced urination is a key symptom of dehydration. If this symptom is combined with dry mucous membranes and lethargy, it requires an immediate increase in feeding frequency and a consultation with a doctor.