Michel Odent has spent his life challenging the conventions of medical orthodoxy. Now in his 80s, the doctor who encouraged women to experience pain-free labour in warm pools of water and was the first to write about the importance of placing newborn babies to the breast has turned Cassandra. His new book is a warning to humanity that we face a grim future by our heedless embrace of medical technology; that the very techniques used to save lives are also changing the human race on an evolutionary level.

The Birth of Homo, The Marine Chimpanzee theorises that the way babies are delivered could be one cause of increased numbers of developmental disorders, psychological problems and addictive behaviours. He has interpreted epidemiological studies that show that a high number of children born by caesarean section or induction go on to be diagnosed with an autism spectrum disorder in support of his theories.

It’s not surprising that the man who trained as a surgeon in France in the 50s and became a guru to the natural birth movement when he pioneered birthing pools and skin-to-skin contact should have a passionate interest in neonatal health. Since retiring in 1985 from Pithiviers hospital south of Paris where he revolutionised the labour ward, he’s spent his time writing and lecturing around the world to midwives and doctors. Now based in London, he likes to describe himself as “an interdisciplinary student of human nature”. Odent maintains an English-language database cataloguing scientific papers on pregnancy, birth and epidemiology. He is tireless in his output, producing five books in the last 10 years alone. The inspiration for his latest book came to him a year ago while he was lecturing to an audience of midwives and swimming instructors who work with babies. It draws on his interpretation of recent discoveries in palaeontology, microbiology and genetics and he is eager to see how his arguments are received.

He explores the highly contentious aquatic ape theory at length – the theory that human ancestors descended from the trees via an aquatic evolutionary phase – particularly as it echoes his belief that some women in labour are innately drawn to immersion in water. He is also fascinated by current research into epigenetics – the study of biological mechanisms that switch genes on and off – and studies that investigate how the maternal microbiome – the microscopic organisms, such as bacteria, that inhabit the human body – might affect a baby’s development in pregnancy, delivery and infancy. He is most passionate about advancing his theory that altering the way women conceive and give birth is changing humanity at an evolutionary level. Odent believes that induction using artificial hormones, caesarean deliveries and advances in neonatal medicine have led to more babies being born to mothers who might otherwise have not survived.

It is one of the biggest problems for humanity today and people don’t realise that

“One effect of modern obstetrics is to neutralise the laws of natural selection – the laws that foiled us all [in the past]. We have neutralised those laws. It means that at the beginning of the 20th century, a woman who could not give birth naturally would die, whereas the one in the village who could give birth easily would have 12 children. Today, the number of children one has depends on other factors than the physical capacity to give birth.

“I mainly talk about obstetrics, but we can also talk about conception. If you cannot have a child, you can have medicalised conception. So we have neutralised the laws of natural selection. It is one of the biggest problems for humanity today and people don’t realise that. Any mathematician, any statistician interested in this topic will find ways to calculate what will happen – in my book I give several examples.”

Odent cites the discovery in the 70s that medication could treat rhesus incompatibility disease that has since saved hundreds of thousands of lives. It’s made it possible for parents who are rhesus incompatible to have several babies. He also cites research into breech births that has shown a genetic component: “In the past, breech births were more dangerous than head first, but suddenly with the advent of modern caesarean techniques, they are not more dangerous. So the people with the genes for breech birth (and it can come from the mother or the father) are able to have the same amount of babies. This is a mathematical fact.”

Where Odent moves on to far more controversial ground is in his selective interpretation of two large longitudinal studies into higher rates of caesareans and induction among children later diagnosed with autism spectrum conditions. These case-control studies used population-based data done in 2002 and 2004 and found an association with caesarean deliveries and autism. Odent claims that the increase in prevalence in cases of autistic spectrum disorders cannot be ascribed solely to increased awareness and changes in the definition of autism. His concerns focus on synthetic oxytocin used to induce labour, the increasing number of caesareans and the environmental conditions in the womb. He suggests that some or all of these factors may in some cases trigger a genetic predisposition to develop autism.

But correlation does not equal causation. A very different interpretation of the higher rates of autism among children born via intervention comes from the American paediatrician and autism specialist Paul Wang: “A foetus with developmental issues may have low muscle tone that can interfere with moving into proper position for natural delivery. In this and other ways, the foetus plays a crucial role in initiating and advancing natural labour.”

Facebook Twitter Pinterest ‘Today, the number of children one has depends on other factors than the physical capacity to give birth,’ says Michel Odent. Photograph: Virginia Star/Getty Images

Others have pointed out that the higher rates may not be an indication that birth interventions have triggered autism but that the difficulties associated with autism – motor planning, hypo or hyper sensory differences, communication impairments – may make it difficult for the already autistic baby in the womb to engage in the birth process in the standard way.

Dr Carole Buckley, the Royal College of General Practitioners’ clinical representative on autism, is disturbed by the hypothesis: “There is no evidence to support the claims in this book and it is extremely unhelpful of Dr Odent to make them. Suggesting that inducing labour or delivering a baby via caesarean may lead to autism is irresponsible. It will only increase anxiety and feelings of guilt or inadequacy that women often feel when they need intervention to give birth to their babies.”

Worrying anxious parents is the last thing that Odent believes is helpful. “I put a caveat in my books – they are not for pregnant women. I tell them not to read them. They are books for people who are interested in the future of human beings – preferably ones with a scientific background, people interested in thinking in terms of the future and the future of the species. That’s the public I want to reach.”

This may seem a little disingenuous when the book’s small publisher specialises in birth and parenting guides. Trying to tease out of Odent whether he’s arguing that would-be parents who have problems with fertility or delivery should not embrace medical technology in case it increases the risk of autism, results in a defensive answer:

“I’m not thinking that way – not in terms of opinion and judging, I’m just observing. What I am saying is that people think in the short term, which is what we do in general – our objective is always what can we do now? So if we say that everyone can have a baby, from a short-term perspective, that is positive. But I am not talking about the short term, I am thinking of the future of mankind. There have been human beings on this planet for millions of years and how long can humanity survive now? It’s probably a negligible number of years in comparison with the past.”

Those who see autism and other developmental disabilities as differences to be accommodated and accepted rather than something to be prevented may well find the tone of his concluding chapter worrying:

“We suggest that the neutralisation of the laws of natural selection by obstetrics and other branches of reproductive medicine should be given a prominent place as an apparently irreversible factor: it tends to set forward the ‘Doomsday clock’. It is urgent to realise the probable and unprecedented evolutionary effects of easy, fast and safe techniques of caesarean section.”

It’s a considerable shift in Odent’s image from the benign natural-birth pioneer to the doomsayer; it will be interesting to see how his arguments are evaluated.

• The Birth of Homo, The Marine Chimpanzee by Michel Odent (Pinter & Martin Ltd, £11.99). To order a copy for £10.19, go to guardianbookshop.com or call 0330 333 6846. Free UK p&p over £10, online orders only. Phone orders min. p&p of £1.99.