Large weight loss then gain in newborn

[Imtootired]

My baby was 3.6 kg at birth then two days later was 3.05. They’re only supposed to lose 10% of birthweight. The midwife said that he seems very healthy and has dirty and wet nappies so she would come back the next two days to check he’s gaining weight. Usually that would be readmission to hospital. Baby is breastfed. She came back the next two days and he was putting on weight. The next week a child health nurse came and he had put on quite a bit. Around 56g per day. Now a week later he’s put on almost 500g in a week! Which is double the average. When he’d lost so much in two days after birth myself and the health care workers thought that maybe the birthweight was wrong because he seems so healthy, so many wet and dirty nappies etc and it was around 600g so would usually be a worry. I thought that the birthweight must have been wrong. Apparently they are usually back to their birthweight around two weeks after birth so I weighed him today at 2 weeks 3 days old and he’s 3.9 kg. Does this mean the birthweight might have been correct? I don’t know why he seems to be losing then gaining so much weight. Luckily I’m not too worried because he’s feeding well and very happy but I’m so confused and curious.

By the way he looks very healthy but he’s not a particularly chubby baby. I had a fluid drip in labour and apparently that can puff babies up a bit with fluid but it wouldn’t usually be that much. His weighloss after birth was around 18% of body weight I think

Was he a c section baby, an over due baby and had you been on a drip?

And the midwife who weighed him two days after birth said he doesn’t look like a 3.6kg baby, but I don’t know

He was born when I went into labour at 38 weeks exactly and I had a drip. I wasn’t huge during pregnancy either so was surprised when they said 3.6

All that sounds fine to me. They can gain a lot quite quickly in the early days once they get going. Where has that fallen on the centile chart? That means much more than the absolute values.

But all babies are different. My first lost 12% by day 3 and didn’t regain birthweight until day 26 (was breast and then a mix of breast and formula). My 2nd lost only 6% and was back to birthweight in a week. I wouldn’t assume any of those numbers were obviously wrong but it’s always possible for them to be a bit off, especially if the scale needs recalibrating, etc.

Could be that he’s now mastered the latch so is getting more milk when he feeds.

Thanks @mindutopia I’ll put his weights on a chart and see where he falls.
Yes @puds11 he’s definitely a good feeder, I’m very lucky.