Dr Jack – % weight loss

I posted this on % weight loss back in early December on my personal Facebook page, but I believe it bears repeating as there are so many new people on this community page.

So maybe now it’s time to talk about % weight loss. In many, if not most postpartum areas in North America, someone has come up with the notion that 10% weight loss (7% in some places) means the baby is dehydrated and needs to be supplemented. This number (or these numbers) come out of nowhere with no evidence to back them up. And % weight loss actually means nothing at all. Why?

1. Most mothers in North America receive intravenous fluids during the labour and birth and often receive quite large volumes. Some of that fluid goes over to the baby and so babies are born “overhydrated” and “extra heavy”. They start to pee out that fluid in the hours after birth and so “lose weight” which is not true weight loss. This is not taken into consideration when one talks about % weight loss. Two recent studies show this to be true.

2. Scales are not the word of God. First of all, when one weighs a baby on one scale and then on another, one cannot compare the two weights. Scales often differ considerably one from the other. I have personally seen one scale (the accurate one) weigh 400 grams (about 12 ounces) more than the other scale which was off. This is dramatic and probably does not happen often, but 80 grams (almost 3 ounces) is not rare and I have seen two scales, made by the same company, same model, sitting one beside the other weigh the same baby but with an 85 grams difference. Let’s make the math easy: 90 grams for a baby born at 3000 grams (about 6lb 10oz) is 3%. So if a baby is weighed on the first scale and then on the second scale which weighs lighter, he automatically has lost 3% of his birth weight. Babies are often weighed on one scale in delivery and another in postpartum.

3. Furthermore, weights are often read wrong and written down incorrectly especially in busy maternity wards.

However, there is a concern. Women in labour who receive large amounts of fluids will often be quite swollen, not only their ankles and fingers, but also their nipples and areolas which makes it difficult for the baby to latch on and therefore the baby may not be getting milk well.

Unfortunately, the approach in most postpartum areas is to give formula, usually by bottle. This is completely the wrong approach. The mother and baby should be helped with breastfeeding. Again, the mother and baby should be helped with breastfeeding!

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