Newborns often take weeks to return to birth weight


Even though doctors often tell parents that newborns will regain weight lost after birth within a week or two, many infants take much longer to achieve this milestone, a U.S. study suggests.

Nearly all newborns lose weight during the first days after birth, regardless of whether they are breastfed or formula fed. Many doctors expect babies to regain those lost ounces and surpass their birth weight within 10 to 14 days.

But by 14 days, 14 percent of babies born vaginally and 24 percent of infants delivered via cesarean section surgeries didn’t return to their birth weight, the study of almost 144,000 newborns found.

“It is normal for newborns to lose a significant amount of weight in the first 1 to 3 days after delivery due to both urinating excess fluid and limited intake,” said lead study author Dr. Ian Paul, a researcher at Penn State College of Medicine in Hershey, Pennsylvania.

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Weight Change Nomograms for the First Month After Birth

Clinicians expect newborns to surpass birth weight by age 10 to 14 days, yet few studies have examined the natural history of weight change in the weeks after birth. We sought to determine the distribution of weight loss and subsequent regain during the first month, the proportion not surpassing birth weight by 14 and 21 days, and whether findings differed by delivery mode.

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External Validation of Early Weight Loss Nomograms for Exclusively Breastfed Newborns

Nomograms that show hour-by-hour percentiles of weight loss during the birth hospitalization were recently developed to aid clinical care of breastfeeding newborns. The nomograms for breastfed neonates were based on a sample of 108,907 newborns delivered at 14 Kaiser Permanente medical centers in Northern California (United States). The objective of this study was to externally validate the published nomograms for newborn weight loss using data from a geographically distinct population.

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Early Weight Loss Nomograms for Exclusively Breastfed Newborns

The majority of newborns are exclusively breastfed during the birth hospitalization, and weight loss is nearly universal for these neonates. The amount of weight lost varies substantially among newborns with higher amounts of weight loss increasing risk for morbidity. No hour-by-hour newborn weight loss nomogram exists to assist in early identification of those on a trajectory for adverse outcomes.

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Early Weight Loss Nomograms for Formula Fed Newborns

Data regarding delivery mode, race/ethnicity, feeding type, and weights were extracted from electronic medical records of the birth hospitalization at 14 Kaiser Permanente Northern California hospitals between 2009 and 2013. Newborns whose first feeding was formula from a cohort of 161471 healthy, term, singleton neonates born at ≥36 weeks’ gestation between 2009 and 2013 were identified. Quantile regression was used to create nomograms stratified according to delivery mode; percentiles of weight loss were estimated as a function of time among formula-fed neonates. Weights measured subsequent to any breast milk feeding were excluded. Percentiles were determined through 48 and 72 hours of age for those born vaginally and via cesarean delivery, respectively.

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Study shows some newborns lose weight much faster than previously recognized

Online tool is first to help parents and pediatricians assess newborn weight loss

Using weights obtained from over 100,000 Northern California babies, a new study is the first to detail the weight loss patterns of exclusively breastfed newborns. The results show that some breastfed babies lose weight faster and for a longer period than was previously recognized. Continue reading…