The thick yellow line represents a standard growth rate of an average baby in the womb. You and I and most of everyone else had to climb that yellow line in pretty much the same way before we did much else. It was three months of ‘nothing’ followed by a slow start, steady increase and steep finish. Much like climbing Everest I hear - which probably takes 9 months too.
The thin blue line is Wallace. You may be surprised to hear that between 10 and 20 percent of all babies are born pre-term or before 37 weeks gestation. (You can also call it ‘pre-mature’ but apparently that offends some people who believe pre-maturity should refer to ‘organ development’ and ‘pre-term-ness’ to womb-time. Wallace and I couldn’t care less :)
It turns out that babies double their weight in just two months between 7 and 9 months of 'womb time'. They put on a lot of fat right at the end before taking on the 'real world'. Therefore, Wallace, being born two months early, came out roughly half the weight of the average fully grown baby, and missing a lot of fat.
Wallace has taught me many interesting facts. For example: all babies lose a good chunk of their birth weight (~15%) in the first week after birth and have to gain it back in the second week. This happens because so much of their initial weight is ‘womb fluid’ or ‘juice’ or something like that. It's not 'real' weight so it just 'goes away' somehow.