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Physiologic newborn weight loss — USMLE Step 3 MCQ

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EasyPediatrics (well-child, chronic management)Physiologic newborn weight lossUSMLE Step 3

A 3-day-old breastfed newborn has lost 6% of birth weight. He has 4 wet diapers daily, normal vital signs, and no jaundice below the chest. Latch is adequate, and examination is normal. His parents are worried that breast milk is insufficient. Which of the following is the most likely explanation for this patient's findings?

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Correct answer: E — Expected early neonatal diuresis and limited initial intake

Weight loss up to about 7% to 10% in the first days of life can be physiologic when hydration and feeding are otherwise reassuring.

Reference: AAP breastfeeding and newborn care guidance