700g weight gain a month seems healthy for a 1 month old baby. Most babies should decrease around 10% weight during their first week, the subsequently increase approx 125g-200g a week.
Here's a schedule of roughly how much weight a baby should gain.
2 weeks to 4 months - 125-200g (5-8oz)per week
4 to 6 months - 50-150g (2-6oz)per week
6 to 12 months - 25-75g (1-3oz)per week
Remember, what's important on top of weight gain is also to ensure your LO is peeing, pooing and not dehydrated.
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