Researchers found that 50% of newborns reached or exceeded their birth weight at 9 days and 10 days after vaginal and cesarean section births, respectively, but 14% of those born vaginally and 24% of those born by C-section had not reached their birth weight at 14 days. The findings in Pediatrics, based on 2009 to 2013 data involving nearly 144,000 infants born at or near full term with healthy birth weight, also showed that 5% of those born vaginally and 8% of those born by C-section hadn't regained their birth weights by 21 days of life.
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