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Health: Boys born to overweight women are 40 per cent more likely to grow up infertile, study finds 

The sons of women who were overweight prior to giving birth are around 40 per cent more likely to grow up to be infertile, a study has warned.

Researchers from Denmark studied 9,232 adults — of whom around nine per cent were found to suffer from infertility.

The team found an association between mothers who had a body mass index, or ‘BMI’, of 25 or more in pregnancy and a higher risk of infertility in male children.

The same did not seem to apply, however, to the daughters of overweight women. 

Obesity causes a number of changes in the body which can have impacts on a growing foetus — and, in particular, lead to inflammation.

It is believed that hormone disruptions or mineral deficiencies resulting from obesity can also slow an unborn child’s development.

In the UK, more than half of all pregnant women are overweight or obese — an issue which increases the risk of miscarriages and stillbirths.

Research has shown that youngsters born to overweight parents are much more likely to become fat themselves — leading to type 2 diabetes and heart disease.

The sons of women who were overweight prior to giving birth are around 40 per cent more likely to grow up to be infertile, a study has warned (stock image)

‘Infertility is a global public health issue and it is important that research focus on addressing risk factors,’ said paper author and epidemiologist Linn Arendt of Denmark’s Aarhus University.

‘We know that children born to mothers in the overweight or obesity weight range face higher risks of several adverse outcomes, both in the short and long term.’

Rates of infertility have soared in the past three decades — with an eighth of all couples now finding themselves unable to conceive after a year or longer of trying. 

According to experts, a third of cases of inferltity are the result of a man’s reproductive issues — and a similar percentage the result of a woman’s issues.

The final third of cases are thought to be caused by a combination of both — or are a result of other, unknown, factors.

According to Dr Arendt and her colleagues, the obesity epidemic could be helping to fuel this problem.

‘These findings add to evidence that weight during pregnancy may also affect male future reproductive health,’ said Dr Arendt.

‘Prevention of overweight during pregnancy may be an important tool to preserve fecundity in future generations.’ 

In the researchers’ study, just over nine per cent of participants were infertile — a rate lower than global figures given the age of the subjects, who were in their 30s.

After accounting for potential confounding factors like the mother’s age, smoking history and alcohol habits, the team found that sons of women whose BMI had exceeded 25 kg/m2 before pregnancy were 40 per cent more likely to be infertile.

'These findings add to evidence that weight during pregnancy may also affect male future reproductive health,' said Dr Arendt. 'Prevention of overweight during pregnancy may be an important tool to preserve fecundity in future generations' (stock image)

‘These findings add to evidence that weight during pregnancy may also affect male future reproductive health,’ said Dr Arendt. ‘Prevention of overweight during pregnancy may be an important tool to preserve fecundity in future generations’ (stock image)

‘Maternal overweight could affect the offspring’s reproductive health through several potential mechanisms,’ explained Dr Arendt.

‘Fatty tissue is hormonally active, and foetal exposure to, for example, leptin, androgens and oestrogens has been suggested to interfere with development of the reproductive system.’

This, she said, ‘can induce changes which might not manifest until sexual maturity.’

‘Some endocrine-disrupting chemicals accumulate in adipose tissue and may become bioavailable and enter the maternal and the foetal bloodstream during remodelling of maternal fat stores during pregnancy.’

‘Obesity is also associated with low-grade metabolic inflammation, a proposed factor in programming of reproductive fitness early in life.’

Rates of infertility have soared in the past three decades — with an eighth of all couples now finding themselves unable to conceive after a year or longer of trying. According to experts, a third of cases of inferltity are the result of a man's reproductive issues — and a similar percentage the result of a woman's issues. The final third of cases are thought to be caused by a combination of both — or are a result of other, unknown, factors

Rates of infertility have soared in the past three decades — with an eighth of all couples now finding themselves unable to conceive after a year or longer of trying. According to experts, a third of cases of inferltity are the result of a man’s reproductive issues — and a similar percentage the result of a woman’s issues. The final third of cases are thought to be caused by a combination of both — or are a result of other, unknown, factors

Past studies on boys and girls have suggested that there may be a link between maternal overweight and the earlier onset of puberty — as well as other hormonal markers of reproductive health.

In boys, maternal overweight has been found to increase the risk of genital deformities and reduced semen quality.

‘To the best of our knowledge, no previous studies have investigated the association between maternal overweight during pregnancy and infertility in their sons or daughters,’ said Dr Arendt said.

‘This study supports the hypothesis that maternal overweight affects reproductive health in male offspring, but further studies are needed.’

A previous study from the US found that boys — but not girls — born to obese mothers had worse motor skills at the age of three and lower IQ scores at seven.

Obese women are advised to lose weight before becoming pregnant, in the interests of both their own and their baby’s health.

However, pregnant women who are obese are not recommended to try to lose weight as this may not be safe, the NHS have warned — and, furthermore, there is no evidence that losing weight while pregnant reduces the chance of complications.

The full findings of the study were published in the journal Acta Obstetricia et Gynecologica Scandinavica.

THE CAUSES OF MALE INFERTILITY

The most common cause of infertility in men is poor-quality semen, the fluid containing sperm that’s ejaculated during sex.

Possible reasons for abnormal semen include:

  • a lack of sperm – you may have a very low sperm count or no sperm at all
  • sperm that aren’t moving properly – this will make it harder for sperm to swim to the egg
  • abnormal sperm – sperm can sometimes be an abnormal shape, making it harder for them to move and fertilise an egg

Many cases of abnormal semen are unexplained.

There’s a link between increased temperature of the scrotum and reduced semen quality, but it’s uncertain whether wearing loose-fitting underwear improves fertility.

Testicles

The testicles produce and store sperm. If they’re damaged, it can seriously affect the quality of your semen.

This can happen as a result of:

  • an infection of your testicles
  • testicular cancer
  • testicular surgery
  • a problem with your testicles you were born with (a congenital defect)
  • when one or both testicles hasn’t descended into the scrotum, the loose sac of skin that contains your testicles (undescended testicles)
  • injury to your testicles

Sterilisation

Some men choose to have a vasectomy if they don’t want children or any more children.

It involves cutting and sealing off the tubes that carry sperm out of your testicles (the vas deferens) so your semen will no longer contain any sperm.

A vasectomy can be reversed, but reversals aren’t usually successful. 

Hypogonadism

Hypogonadism is an abnormally low level of testosterone, the male sex hormone involved in making sperm.

It could be caused by a tumour, taking illegal drugs, or Klinefelter syndrome, a rare syndrome where a man is born with an extra female chromosome.

Medicines and drugs

Certain types of medicines can sometimes cause infertility problems.

These medicines are listed below:

  • sulfasalazine – an anti-inflammatory medicine used to treat conditions such as Crohn’s disease and rheumatoid arthritis; sulfasalazine can decrease the number of sperm, but its effects are temporary and your sperm count should return to normal when you stop taking it
  • anabolic steroids – are often used illegally to build muscle and improve athletic performance; long-term abuse of anabolic steroids can reduce sperm count and sperm mobility
  • chemotherapy – medicines used in chemotherapy can sometimes severely reduce sperm production
  • herbal remedies – some herbal remedies, such as root extracts of the Chinese herb Tripterygium wilfordii, can affect the production of sperm or reduce the size of your testicles
  • illegal drugs, such as marijuana and cocaine, can also affect semen quality.

Source: NHS 


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