Babies born by caesarean section are more likely to have autism or develop ADHD, according to a study of more than 20 million children.
Research has shown that babies with a C-section have a 33 percent higher chance of autism and 17 percent more likely to get an attention deficit hyperactivity disorder.
But scientists disagree about whether birth is actually related to the disorders, or whether both are the consequences of deeper issues.
In their article, the researchers suggested that non-exposure to bacteria in the vaginal tract or experiencing the natural stress response during normal birth can affect brain development.
Experts who were not involved in the study, however, said that caesarean sections are more likely to be necessary due to underlying factors that can themselves be linked to autism.
They said there was & # 39; good evidence & # 39; is that C-sections do not directly cause autism and that parents should not be afraid of the procedure.
About a quarter of UK mothers give birth per C-section. The procedure is usually used for medical reasons, but women can also choose one (stock image)
Caesarean sections have tripled around the world in 30 years, with more than one in five children now born through operations, compared to six percent in 1990.
The researchers suggested that the ideal share of caesarean sections was between 10 and 15 percent – the percentage is around 25 percent in the UK.
The procedure involves cutting over the abdomen and surgically removing the baby, rather than pushing the baby through the vagina.
C-sections are usually done to protect the health of mother and baby, but women can also choose to have them for cultural reasons or if they are afraid of giving birth naturally.
Studies have already shown that babies born in this way are more likely to become obese, suffer from allergies or develop asthma, type 1 diabetes or leukemia.
However, evidence of links between C-sections and psychiatric disorders is & # 39; incomplete & # 39 ;, according to the Swedish Karolinska Institutet team.
Led by PhD student Tianyang Zhang, they analyzed the results of 61 previous studies that recorded details of 20,607,935 births in 19 countries.
They found that children born through the C-section were one third more likely to get autism and 17 percent more likely to be diagnosed with ADHD, compared to children born in a vaginal birth.
WHAT ARE THE MEDICAL REASONS FOR A CAESAREAN?
There are several reasons why a doctor may recommend having a caesarean section instead of giving birth vaginally.
If you had complications in a previous pregnancy or birth, or in your current pregnancy, you may be advised to have a planned or elective caesarean section or a planned repeated caesarean section.
If you were planning to give birth vaginally, but complications during delivery or birth mean that you are advised to give birth by caesarean section, then you have a so-called unplanned or emergency caesarean section.
Here are some reasons why doctors can opt for a planned caesarean section rather than a vaginal delivery:
- You have already had at least a caesarean section.
- Your baby is in a bottom-down or breech position.
- Your baby is in a lateral (transverse) position or continues to change position (unstable lie).
- You have a low-lying placenta (placenta praevia).
- You have a medical condition such as heart disease or diabetes.
- You have lost a baby in the past, before or during delivery.
- You expect twins or more.
- Your baby is not growing as well as it should be in your womb.
- You have severe pre-eclampsia or eclampsia, which makes it dangerous to postpone birth.
Source: Baby Center
These results remained the same whether the C-section was done for medical reasons or was chosen by the mother, they said.
The causes of autism are not well understood and it is believed that there are several genetic factors that contribute to the condition.
Previous studies, Ms. Zhang's team wrote in their article, suggested that non-exposure to bacteria in the vaginal tract could stop the baby's immune system from developing properly, potentially leading to brain problems.
And sensory development can be affected by the lack of natural stress response during birth, she added.
But experts who were not involved in the newspaper said that this was unlikely and that the results should not deter mothers or doctors from opting for caesarean sections.
Professor Andrew Shannan of Kings College London said: “The need for caesarean section is often caused by problems that can affect brain function, such as a malfunctioning placenta.
& # 39; Caesarean section itself is highly unlikely in these mental health states, from our current understanding of brain physiology and the effects of caesarean section.
& # 39; Women should not be alarmed by the need for a caesarean section that is often performed to reduce the risk to their baby. & # 39;
And Richard Kennedy, medical director at Birmingham and Solihull Local Maternity System, added: “Women need reassurance that a caesarean section in the UK is a very safe operation.
& # 39; Performed for proper clinical reasons, it can be life-saving for mother and baby.
& # 39; Any association with pediatric outcomes is more related to underlying maternal disorders than to Caesarean section itself. & # 39;
Mrs Zhang's team suggested that a link between the C-section and brain damage could lead to a reduction in the number of unnecessary caesarean sections.
They said: “Public health concerns have arisen because … unnecessary Caesarean sections can be delivered to (high-income countries).
& # 39; Despite the fact that it is a life-saving procedure in the presence of complications, there is no evidence to our knowledge that caesarean section, if not (done for medical reasons) is beneficial to the offspring. & # 39;
The team admitted that children most likely to be born by C-section may also be those who are most likely to get autism or ADHD regardless.
WHAT ARE THE SIGNS OF AUTISM?
According to the US Centers for Disease Control and Prevention, people with autism have problems with social, emotional, and communication skills that usually develop before the age of three and last through the life of a person.
The causes of the disorder are not well understood and it is thought that there are several contributing genetic factors.
According to the National Autistic Society, the National Autistic Society believes that more than one percent of the population is autistic, about 700,000 people in the UK or 3.2 million in the US.
Specific signs of autism include:
- Responses to smelling, tasting, looking, feeling or sounding are unusual
- Difficulty in adapting to routine changes
- Unable to repeat or repeat what is being said to them
- Difficulties in expressing desires with words or movements
- Unable to discuss their own feelings or those of others
- Difficulties with acts of affection such as hugging
- Prefer to be alone and avoid eye contact
- Difficulties with regard to other people
- Cannot point at objects or look at objects when others point to them
They wrote: & # 39; Caesarean section choice can be requested by the mother due to cultural preferences, previous negative birth experience or fear of birth, which may indicate a genetic vulnerability to factors related to psychological changes such as stress and his with neurological or psychiatric disorders in the offspring.
& # 39; Emergency caesarean section, however, occurs in more traumatic situations (for example, severe fetal distress, pre-eclampsia) associated with multiple negative birth indications. & # 39;
Dr. James Findon, psychology teacher at King's College, said: & it's important to note that the results do not suggest that caesarean section causes neurological disorders.
& # 39; Indeed, there is good evidence from studies by siblings that there is no causal relationship between caesarean section and autism.
& # 39; The association may arise from a genetic or environmental factor that is common to both neurological disorders and the need for caesarean section.
& # 39; Parents should be assured that caesarean sections are a largely safe procedure if they are medically indicated. & # 39;
Ms. Zhang's team also investigated whether C-sections were related to learning disabilities, obsessive compulsive disorders or eating disorders, but found no connections.
The research was published in the journal JAMA Network Open.
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