Children conceived through IVF do not develop differently, study finds

Children conceived through IVF do NOT develop differently: Study finds difference in their height, weight and body frame disappear by late teens

  • IVF children tend to be smaller, skinner and less heavy in early age groups 
  • Study of 158,000 children found these differences are gone by age 17 
  • University of Bristol researchers say parents should be ‘reassured’

IVF babies don’t end up being smaller than children conceived naturally, research claimed today.

Fertility experts found differences in height, weight or body size normally even out once they hit their late teenage years. 

Parents should be ‘reassured’ by the ‘important work’, the University of Bristol team claimed.

IVF babies end up no different in height, weight or body frame than those born from natural conception, a study led by the University of Bristol claimed today


In-vitro fertilisation, known as IVF, is a medical procedure in which a woman has an already-fertilised egg inserted into her womb to become pregnant.

It is used when couples are unable to conceive naturally, and a sperm and egg are removed from their bodies and combined in a laboratory before the embryo is inserted into the woman.

Once the embryo is in the womb, the pregnancy should continue as normal.

The procedure can be done using eggs and sperm from a couple or those from donors. 

Guidelines from the National Institute for Health and Care Excellence (NICE) recommends that IVF should be offered on the NHS to women under 43 who have been trying to conceive through regular unprotected sex for two years.

People can also pay for IVF privately, which costs an average of £3,348 for a single cycle, according to figures published in January 2018, and there is no guarantee of success.

The NHS says success rates for women under 35 are about 29 per cent, with the chance of a successful cycle reducing as they age.

Around eight million babies are thought to have been born due to IVF since the first ever case, British woman Louise Brown, was born in 1978.

Chances of success

The success rate of IVF depends on the age of the woman undergoing treatment, as well as the cause of the infertility (if it’s known).

Younger women are more likely to have a successful pregnancy. 

IVF isn’t usually recommended for women over the age of 42 because the chances of a successful pregnancy are thought to be too low.

Between 2014 and 2016 the percentage of IVF treatments that resulted in a live birth was:

29 per cent for women under 35

23 per cent for women aged 35 to 37

15 per cent for women aged 38 to 39

9 per cent for women aged 40 to 42

3 per cent for women aged 43 to 44

2 per cent for women aged over 44

Lead author Dr Ahmed Elhakeem, an epidemiologist, said: ‘In the UK just over one in 30 children have been conceived by assisted reproduction.

‘So we would expect on average one child in each primary school class to have been conceived this way. 

‘Since the first birth of a child by IVF, concerns have been raised about the risks to the children conceived.

‘Parents and their children can be reassured that this might mean they are a little bit smaller and lighter from infancy to adolescence, but these differences are unlikely to have any health implications.’

The study, published in JAMA Network Open, tracked more than 158,000 children into adulthood. 

It included roughly 2.5 per cent who were conceived through assisted reproductive technology, such as IVF.  

They looked at height, weight and BMI data in children born via natural conception or ‘assisted reproductive technology’ at different ages.

Their bodyfat percentage and waist circumference were also compared. 

Children came from countries in Europe — including the UK — as well as Australia, New Zealand, Canada, China and Singapore.  

Statistical analysis showed children aged less than three months old were around 0.27cm shorter, on average, than those born via natural conception.

But as they got older, the difference got smaller, with naturally-conceived children only 0.06cm taller by the time they were 17, on average.

A similar trend was spotted for weight, with babies born 0.27kg lighter if they were conceived through artificial methods, on average. 

In adulthood they were actually 0.07kg heavier, however. 

Children born through fertility treatment had a BMI that was 0.09 marks higher by the time they turned 17, despite being 0.18 lower as an infant.

Peter Thompson, chief executive of the Human Fertilisation and Embryology Authority (HFEA), said: ‘Around one in seven couples have difficulty conceiving in the UK which leads to around 53,000 patients a year having fertility treatment (IVF or donor insemination).

‘The findings from this study will come as a welcome relief to these patients who begin treatment in the hope of one day having healthy children of their own.

‘Health outcomes in children conceived using assisted reproductive technology is a high priority for the HFEA and we monitor the latest research and provide information for patients and professionals.

‘Anyone considering fertility treatment can access this and other high-quality impartial information on fertility treatments and UK licensed clinics at’

Women under 42 who are struggling to conceive should be given three cycles of IVF under NHS guidelines.

But local health chiefs decide who can access funded treatment, leading to a ‘postcode lottery’ across Britain. 

Some trusts offer the recommended cycles, others don’t.

The Government’s long-awaited Women’s Health Strategy published last week aims to reduce this imbalance, while broadening who is able to get it for free.