Growth chart misunderstanding
Dr Byrne says there is also a fundamental misunderstanding among many parents around growth charts and that a ‘chubby baby is a happy baby’.
Baby weigh-ins are a rite of passage for parents, but some parents are left with a feeling of failure when their child is sitting below the 50th percentile.
Many parents think a baby tracking above the 50th percentile is good, and below is bad, but by definition, half the population has to be above the 50th, and half below. It is the trajectory which is important.
“Some really neat research from the United States presented several growth charts to parents. Each chart had a (theoretical) child’s growth mapped on it and parents were asked to rate which growth patterns they preferred, or considered most ‘healthy’,” Dr Byrne says.
“The majority of parents preferred infants to track at higher percentiles compared with normal growth trajectories on lower percentiles. This suggested that people think a baby tracking above the 50th percentile is good, and below is bad, while they are unaware that tracking roughly along the same percentile (any percentile) depicts ‘normal’ growth.
“The ‘chubby baby is a happy baby’ association is one of the few beliefs consistent across cultures, countries, and socioeconomic status.
“Universally parents tend to underestimate their child’s weight i.e. labelling babies or children in the healthy weight range as underweight, and for those children that have been objectively classified as overweight, parents tend to perceive them as a healthy weight.
“This makes a lot of sense, given most of human history has been a time of food scarcity. Extra weight, especially in infancy, conferred a survival advantage.
“Now, our children are born in to an 'obesogenic environment'. Unhealthy food is cheap and readily available, and our surroundings encourage us to move less and sit more.
This means it is vitally important that we feed children in a way that lets them stop eating when they are full, rather than teaching them to ignore their body's signals, or eat for reasons other than hunger.
“This doesn’t mean that having a chubby baby is bad. If we think about the growth charts again for a moment - percentiles by definition, mean that half the population has to be above the 50th, and half below.
“So there are always going to be people of different sizes. If your dad is a rugby forward, you will most likely be a bigger baby than one whose dad is a jockey.
“Measuring weight, length and head circumference over time, with the support of a trusted health professional is the best way for a parent to be reassured their child is growing well.”