Newborns whose mothers were given IV fluids during labor may be losing weight in an attempt to regulate their hydration rather than not getting enough breast milk, Canadian researchers revealed in the International Breastfeeding Journal. As newborn weight loss is commonly used to gauge how well a baby is breastfeeding and whether to introduce formula milk – this new finding should be taken into account, the authors suggest.

Senior researcher, Prof Joy Noel-Weiss from the School of Nursing at the University of Ottawa’s Faculty of Health Sciences, and team set out to find out what the relationship is between IV fluids received by the mother during labor (before C-section delivery), neonatal output (measured by diaper weight), and weight-loss of newborns.

There was a positive link between IV fluids given to the mother during labor, neonatal output, and the loss of weight of the newborn, the authors wrote. At sixty hours after birth, when newborn weight loss is at its highest, there was a positive link between newborn weight loss and maternal IV fluids.

Prof Joy Noel-Weiss said:

“Nurses, midwives, lactation consultants, and doctors have long wondered why some babies lose substantially more weight than others even though all babies get small amounts to eat in the beginning. It appears neonates exposed to increased fluids before birth might be born overhydrated, requiring the baby to regulate his or her fluid levels during the first 24 hours after birth.

We should reconsider the practice of using birth weight as the baseline when calculating newborn weight loss in the first few days following birth. For mothers and their breastfed babies, accurate assessment of weight loss is important. Although more research is needed, based on our findings, we would recommend using weight measured at 24 hours post birth as a baseline. “

The authors have included, alongside the article, a standardized method health care professionals can use to gather and analyze data regarding newborn weight loss in their maternity unit so that they can make better informed decisions when assessing newborn weight changes.

Written by Christian Nordqvist