Is your baby's weight loss normal?

All newborns lose weight in the first days. Let's check if yours is within the safe range.

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weight change
Weight Loss Severity
0%5%7%10%
Birth Weight
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Current Weight
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Age
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What you need to know right now

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Medical Disclaimer: This tool provides general educational estimates. Always consult your prescribing physician or healthcare provider before making medication changes or interpreting results from population-based models.

Frequently Asked Questions

Most newborns lose 5-7% of birth weight in the first 3 days. Breastfed babies may lose up to 10%. This is normal and caused by fluid shifts and limited initial feeding. Birth weight is typically regained by days 10-14.

Contact your pediatrician if: weight loss exceeds 10% of birth weight, baby hasn't started gaining by day 5, or birth weight isn't regained by day 14. Also watch for fewer than 6 wet diapers per day after day 4.

Most newborns regain birth weight by 10-14 days of age. Weight loss typically stops and reversal begins by day 3-5. Formula-fed babies tend to regain slightly faster than exclusively breastfed babies.

Normal causes include: fluid shifts (babies are born with extra fluid), limited colostrum volume before mature milk comes in (day 2-5), and meconium passage. C-section babies may lose more due to extra IV fluids during delivery.

Yes. Breastfed babies typically lose slightly more weight (7-10%) because mature milk takes 2-5 days to come in. Formula-fed babies usually lose 5-7%. Both patterns are normal. The NEWT tool provides feeding-specific reference curves.

Sources

Methodology

This calculator computes weight loss as a percentage of birth weight: (birth - current) / birth * 100. Results are compared against AAP thresholds: up to 7% is normal for vaginal delivery, up to 10% for breastfed/C-section babies.

Newborn weight loss of 5-7% is normal in the first 3-4 days of life. Breastfed babies may lose up to 10%. Most babies regain birth weight by days 10-14. Weight loss exceeding 10% requires medical evaluation.

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