Good kidney health begins before birth

Researchers have found that conditions in the womb can affect kidney development and have serious health implications for the child not only immediately after birth, but decades later. 

In a paper published today in The Lancet an international team, including Monash University's Professor John Bertram and the University of Queensland's Professor Wendy Hoy, reviewed existing, peer-reviewed research on kidney health and developmental programming - the effects of the in utero environment on adult health.

Wendy Hoy

The accumulated evidence linked low birth weight and prematurity - risk factors for high blood pressure and chronic kidney disease later in life - with low numbers of the kidney's filtration units or nephrons.

In Australia, around 30 per cent of the adult population has high blood pressure and one in nine has at least one clinical symptom of chronic kidney disease.

The incidence of both diseases is significantly higher in Indigenous populations. Professor Bertram, Head of the Department of Anatomy and Developmental Biology, has been researching nephrons for two decades.

"The kidney is particularly sensitive to life before birth because we stop making nephrons at 36 weeks gestation. So, for a baby born at term, the process of nephron formation is finished and it cannot be restarted," Professor Bertram said.

John Bertram

Humans are born with an average of one million nephrons and lose up to 6000 each year. However, Professor Bertram's research has shown there is a huge variance in nephron number - from just over 200,000 to around two million.

Further, nephron number is positively related to birth weight - a low birth weight equates to low nephron number and larger babies have a higher nephron number.

Given that low birth weight occurs in 15 per cent of live births worldwide, the study has implications for maternal health and clinical screening processes.

"In terms of maternal health during pregnancy, things like a high fat diet, alcohol consumption, various antibiotics and stress hormones have been shown to have a negative impact on foetal kidney development, although more research needs to be done," Professor Bertram said.

"Further, given the strong associations between birth weight, nephron number and disease later in life, and the fact that a baby's weight is routinely recorded in many countries, we suggest that birth weight should be a parameter that clinicians use to determine how often a patient is screened for kidney function or given a blood pressure test.

"Although a newborn may appear perfect, if their birth weight is low, there may be consequences 40 years down the line. We could be proactive about detecting these diseases in the early stages."

Greek Physician Told Everyone Not to Carry Around Their Baby Boys

The ancient Greek physician Soranus thought that babies, especially boys, should not be carried until four months of age.

Carrying posed the risk of severe testicular injury, Soranus thought.

Today we worry about raising children who aren’t well-adjusted; the Greeks worried about raising children who weren’t eunuchs.

This bias against carrying continued through medieval times.

Meanwhile, at the same time Soranus pronounced this, the many hunter-and-gatherer societies south of him in Africa were regularly carrying their infants. They had always carried their infants. Given their lifestyle, it was essential.

John Whiting

There is some logic here; the anthropologist John Whiting established that infants in cold climates are more likely to be swaddled and put down in a cradle, while those in hot climates are more likely to be carried in a sling.

But once we could control the temperature indoors, we had an infinite amount of choices and a variety of information from well-meaning pseudo-experts.

In the US, for the first half of the 20th century, the medical consensus was something like, “Carry your child? Why are you even touching your child?”

This was an era when experts were telling parents not to kiss their babies. Thankfully most people ignored this dubious advice.

The sudden popularity of slings, beginning in the 1970s, was a radical reversal. It swept away decades of child-rearing wisdom.

If you take the long view all this indecision dates back to a pivot point in human development.

Our hominid ancestors carried their infants without trying, that was the advantage of having a hairy body they could cling to and an opposable toe to assist the infant in gripping.

When they lost both, they squandered an extremely efficient method of child care. Suddenly, parents had to think about what to do with this helpless creature.

Some invented slings, mainly for convenience, to allow them to work and function in a hand-to-mouth environment.

In a sense, the search for infant daycare began with the moment, millions of years ago, that those hominid infants no longer stuck to their parents. In those societies the extended family (sisters, granny, aunts, etc) was readily available to perform this service.

It’s always tempting to see the present as the final point in a journey. It is convenient to believe that we have corrected the mistakes of the past.

We now understand that babies have basic socio-emotional needs; we let ourselves pick up our babies; we carry them when they want to be carried.

The real answer is that we have more time and energy to spend on a small number of children and are charged with guilt that they will become 'psychologically damaged' if we do not attend to their demands for attention.

Questions and Answers to child-rearing will see-saw wildly as our society changes. So watch this space for emerging theories and possible solutions to questions that have yet to be asked.