Would the risk of childhood leukaemia make you reconsider your birth choice? By Salomé Delport
There is nothing quite as heart wrenching as watching a fragile little four-year-old body go through leukaemia treatments. In South Africa, more than 200 childhood leukaemia cases are diagnosed each year – more boys than girls. “Today, around 70% of the 200 children who are diagnosed per year in our country will go on to live full, happy lives with a normal life expectancy,” says Dr Ané Büchner, specialist in child oncology at Steve Biko Academic Hospital and the University of Pretoria.
Even then, though, treatment comes at a price. Low fertility levels and heart problems are possible side effects. These facts beg the question – if a vaginal birth could protect your child against leukaemia, would you opt out of an elective C-section?
Dr Mel Greaves, renowned for his work on childhood leukaemia at the Institute of Cancer Research, University of London, believes the most common form of childhood leukaemia, childhood acute lymphoblastic leukaemia (ALL), can be prevented. It requires only four measures – of which natural birth is the first and crucial step.
The four-piece puzzle
Childhood leukaemia has fascinated researchers for many years. Why would it affect healthy children as young as two or three years old?
The first piece of the puzzle was laid down when it was discovered that one in every 100 babies is born with preleukaemia cells (these have the potential to turn into full-blown leukaemia). Babies without these cells will never develop childhood leukaemia and only those with preleukaemia cells are at risk.
What makes this all the more puzzling is most of these children escape leukaemia. As an example, in a group of 2 000 children, 20 will be born with preleukaemia cells and a strong leukaemia risk. However, only one of this group of 20 will go on to develop leukaemia. So, what protects the other 19 children?
Researchers investigated a variety of explanations, including genes, viruses, environmental carcinogens, and even exposure to radioactivity. No virus was ever isolated and no genes could be tied to it. Investigation into exposures to potential carcinogens didn’t point to a common chemical or even a likely one. Exposure to radioactivity explained a few cases but these were rare exceptions. The risk for leukaemia was too small to justify testing for preleukaemia cells at birth, so parents were left to monitor their children’s health for signs of leukaemia, as with any other disease.
Another inexplicable phenomenon that goes hand-in-hand with childhood leukaemia is a serious infection. Moms would often report their child had experienced one or more episodes of extremely high fever during the six months before the diagnosis.
Like moms, doctors also observed a link between the incidence of infectious fevers and the incidence of childhood leukaemia, which warranted further investigation.
Several studies found a small, but clear, spike in the number of children diagnosed after each flu epidemic. However, children didn’t develop leukaemia only after flu epidemics, a variety of infections were linked to it, too, so the flu virus was not the link.
This is when the second piece of the puzzle fell into place. Investigators found the event of becoming infected was the trigger, rather than any specific microbe behind the infection.
Researchers now had potential in the form of preleukaemic cells and a trigger in the form of a serious infection, but there were still huge gaps in understanding this cancer in a useful way that could lead to a cure or prevention.
Childhood leukaemia and the C-section connection
The third piece turned up from research into C-sections that compared the health of children born by C-section to those born vaginally.
One study by a Greek team compared 1 099 children with leukaemia and without leukaemia, all born between 1996 and 2013. To their surprise, children born by C-section had a significant risk, while no risk was found among children born vaginally.
This led to a spate of studies from the opposite starting point: if you look at a large number of C-sections would you also get more children with leukaemia? The first to confirm this relationship was a 2017 study involving 5018 children.
The present view is that the incidence of ALL is 60% higher in children born by C-section than in children born vaginally.
Role of the microbiome
The C-section studies revealed the fourth piece of the puzzle, too. While there is an indisputable increase in leukaemia among children born by elective (planned) C-section, the same did not apply to children born by emergency C-section. Their risk is as low as that of children born vaginally.
The difference lies in the first microbiome the newborn is exposed to. Your microbiome consists of all those organisms living with you − on your skin, in your gut and in your vagina. Officially, they’re called commensal organisms, which means they benefit us as we do them.
Babies born vaginally and by emergency C-section are exposed to their mom’s vaginal microbes. These organisms are the first to populate the newborn and tweak the baby’s immune system in just the right way.
Ordinarily, the immune system sees all strange cells in the body as the enemy, and attacks them. This first exposure tells our immune system which cells are safe, priming it to be neither overly eager nor lax in protecting us.
C-section babies are born into a very different microbiome. Their “first nations” are the microbes found in theatres and hospitals. These organisms can’t enable gentle priming, resulting in an overly active immune system.
How they all fit together
Ordinarily, the immune system produces white blood cells that effectively kill off all strange germs trying to infiltrate the body. Once the infection is under control, the bone marrow, where white blood cells are made, switches off further production. In poorly primed children, the bone marrow keeps making white blood cells in huge numbers. These cells are dysfunctional and unable to rid the body of infection – which you see as a high fever and recurrent infections.
These cells eventually take over the bone marrow, preventing it from executing its other functions, like producing red blood cells tasked with carrying oxygen to all body cells, and blood platelets, which help blood clot. This explains the symptoms of extreme tiredness and easy bruising and bleeding − the typical signs of leukaemia.
The conclusion is that leukaemia is most likely after a serious infection in a susceptible child who was primed incorrectly.
Are you choosing a higher risk for leukaemia when you choose a planned C-section? This might be the case. According to Cancer Association of South Africa (Cansa), the incidence of leukaemia increases by 1% year on year. At the same time, C-sections are increasing in popularity – though only in the private sector. At South African state hospitals, where only emergency and medically indicated C-sections are allowed, a mere 10% of moms have C-sections, compared to 75% of Discovery’s pregnant moms, according to Dr Noluthando Nematswerani of Discovery Health. The World Health Organization suggests a 15% C-section rate at hospitals and gynaecological practices.
So, do we in fact see more leukaemias among children born in private hospitals? A Cape gynaecologist, who prefers to remain anonymous, says no such stats are available. But, that even if leukaemia could be linked to elective C-sections, he would still recommend planned C-sections to his patients, because there is also another side to the story. “Vaginal birth is far more risky for both mother and baby. Besides, the statistics need careful interpretation. Childhood leukaemia is scarce and affects only around one in 2 000 children. If I’m really honest – I wouldn’t be able to run a full-time practice if I had to deliver babies a couple of nights per week. If I’m tired, I’m a risk to mothers and babies. If it’s really only about microbes, I believe moms can overcome the issue by simply focusing on breastfeeding, skin contact and normal exposure to the environment.”
4-step plan to protect against ALL
- Opt for a vaginal birth – if your health and your baby allow it.
- Breastfeed. If you bottle feed, hold your baby from the very first feed next to your bare skin or breast, to expose her to your own commensal organisms.
- Socialise your baby. The more human contact she has, the more opportunities she gets to pick up all the good tribes of organisms.
- Don’t be excessively hygienic. A good dose of germs from playing on the floor and lawn is actually beneficial.
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