Is my baby gaining enough weight?

The daily number became an obsession

Two weigh-ins a few days apart suggested she was gaining around 30 grams a day. We immediately did the arithmetic and asked whether that was good.

It was. But the maths was less reliable than it looked. Papa became obsessed with the scales. One day Ari had just done a poo and weighed about 75 grams less, and he immediately thought she was losing weight. That was when we understood why daily weighing can create more panic than useful information. The trend matters, not one day's number.

Why daily gain is noisy

Three days is a short window and a lot of things move within it. Different scales, different clothes, a full or empty nappy, a feed that just went in — any of those can be forty or fifty grams on their own.

So a daily figure from two weighings a few days apart is mostly scale noise, with a little growth mixed in.

Weekly is the unit that means something. Same scales, roughly the same time of day, roughly the same amount of clothing.

We assumed a bigger baby should gain more each day. It sounds sensible, but it is the other way round.

Gain per day is fastest early on and slows as she grows. A rate that would be excellent at one month would be unusual at six. So a slowing rate isn't a warning sign — it's the expected shape.

What matters is that she keeps following her own line rather than sliding downwards across the chart.

The premature version

Ari was born at 33 weeks and was due in September, so when we were doing this arithmetic she had only just reached the point when she should have been born.

We asked whether she was still on preterm expectations or had switched to term ones, and honestly that's a question for the people following her rather than a calculation. Her baby’s doctor had her own targets and they were the ones that counted.

If your baby is under any kind of follow-up, ask what they expect and what number would concern them. Then you're watching for something real instead of comparing her to a stranger.