We hear a lot about women’s biological clock and how age affects the chance of pregnancy.

New research shows men’s fertility is also affected by age. When dads are over 50, the risk of pregnancy complications increases.

Data from more than 46 million births in the United States between 2011 and 2022 compared fathers in their 30s with fathers in their 50s.

While taking into account the age of the mother and other factors known to affect pregnancy outcomes, the researchers found every ten-year increase in paternal age was linked to more complications.

The researchers found that compared to couples where the father was aged 30–39, for couples where the dad was in his 50s, there was a:

• 16% increased risk of preterm birth
• 14% increased risk of low birth weight
• 13% increase in gestational diabetes.

The older fathers were also twice as likely to have used assisted reproductive technology, including IVF, to conceive than their younger counterparts.

Dads are getting older

In this US study, the mean age of all fathers increased from 30.8 years in 2011 to 32.1 years in 2022.

In that same period, the proportion of men aged 50 years or older fathering a child increased from 1.1% to 1.3%.

We don’t know the proportion of men over 50 years who father children in Australia, but data shows the average age of fathers has increased.

In 1975 the median age of Australian dads was 28.6 years. This jumped to 33.7 years in 2022.

How male age affects getting pregnant

As we know from media reports of celebrity dads, men produce sperm from puberty throughout life and can father children well into old age.

However, there is a noticeable decline in sperm quality from about age 40.

Female partners of older men take longer to achieve pregnancy than those with younger partners.

A study of the effect of male age on time to pregnancy showed women with male partners aged 45 or older were almost five times more likely to take more than a year to conceive compared to those with partners aged 25 or under. More than three quarters (76.8%) of men under the age of 25 years impregnated their female partners within six months, compared with just over half (52.9%) of men over the age of 45.

Pooled data from ten studies showed that partners of older men are also more likely to experience miscarriage. Compared to couples where the male was aged 25 to 29 years, paternal age over 45 years increased the risk of miscarriage by 43%.

Older men are more likely to need IVF

Outcomes of assisted reproductive technology, such as IVF, are also influenced by the age of the male partner.

A review of studies in couples using assisted reproductive technologies found paternal age under 40 years reduced the risk of miscarriage by about 25% compared to couples with men aged over 40.

Having a male under 40 years also almost doubled the chance of a live birth per treatment cycle. With a man over 40, 17.6% of treatment rounds resulted in a live birth, compared to 28.4% when the male was under 40.

How does male age affect the health outcomes of children?

As a result of age-related changes in sperm DNA, the children of older fathers have increased risk of a number of conditions. Autism, schizophrenia, bipolar disorders and leukaemia have been linked to the father’s advanced years.

A review of studies assessing the impact of advanced paternal age reported that children of older fathers have increased rates of psychiatric disease and behavioural impairments.

But while the increased risk of adverse health outcomes linked to older paternal age is real, the magnitude of the effect is modest. It’s important to remember that an increase in a very small risk is still a small risk and most children of older fathers are born healthy and develop well.

Improving your health can improve your fertility

In addition to the effects of older age, some chronic conditions that affect fertility and reproductive outcomes become more common as men get older. They include obesity and diabetes which affect sperm quality by lowering testosterone levels.

While we can’t change our age, some lifestyle factors that increase the risk of pregnancy complications and reduce fertility, can be tackled. They include:

• smoking
• recreational drug taking
• anabolic steroid use
• heavy alcohol consumption.

Get the facts about the male biological clock

Research shows men want children as much as women do. And most men want at least two children.

Yet most men lack knowledge about the limitations of female and male fertility and overestimate the chance of getting pregnant, with and without assisted reproductive technologies.

We need better public education, starting at school, to improve awareness of the impact of male and female age on reproductive outcomes and help people have healthy babies.

For men wanting to improve their chance of conceiving, the government-funded sites Healthy Male and Your Fertility are a good place to start. These offer evidence-based and accessible information about reproductive health, and tips to improve your reproductive health and give your children the best start in life.

Karin Hammarberg, Senior Research Fellow, Global and Women’s Health, School of Public Health & Preventive Medicine, Monash University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Maybe you feel worn out. Perhaps you’re also having trouble losing weight. Generally, you just don’t feel 100%.

Could it be Hashimoto’s disease? This common autoimmune thyroid disorder is when your immune system (which fights off viruses and bacteria), mistakenly attacks a part of your body. In this case, it’s your thyroid – a gland located at the base of your neck – and can cause low thyroid hormones levels (hypothyroidism).

Hypothyroidism affects one in 33 Australians and Hashimoto’s is one of the most common thyroid conditions in first-world countries.

While symptoms can be subtle, untreated Hashimoto’s can cause long-term problems with your heart, memory and fertility. Here is what you need to know.

What happens when you have Hashimoto’s?

Your thyroid gland is a butterfly-shaped gland in the neck. It is essential in regulating things like muscle function, digestion, metabolism, the heart and lungs. In children, thyroid hormones are also needed for normal growth and development.

Hashimoto’s thyroid disease, named after the Japanese doctor who discovered it in 1912, is also known as Hashimoto’s thyroiditis or chronic lymphocytic thyroiditis. The disease can cause the immune system to mistakenly produce proteins called antibodies (thyroid peroxidase and thyroglobulin). These can cause inflammation and long-term damage to the thyroid gland. Over time, as thyroid tissue is inflamed and/or destroyed, there can be a decrease in the production of thyroid hormones (hypothyroidism).

Hashimoto’s can present subtly at first. If you only have antibodies with no change in thyroid levels, it is likely you won’t have any symptoms.

However, as the disease progresses, you may experience fatigue, weight gain (or difficulty losing weight), increased sensitivity to the cold, constipation, dry skin, muscle aches, irregular or heavy menstrual cycles, enlarged thyroid (goitre) and occasionally hair loss, including at the ends of your eyebrows.

What causes Hashimoto’s thyroid disease?

Several risk factors can contribute to the development of Hashimoto’s including:

• genetic risk – your risk is higher if you have family members with Hashimoto’s

• gender – women are up to ten times more likely than men to develop the disease

• age – you are more likely to develop the disease from 30 to 50 years of age

• autoimmune condition – having another autoimmune condition like systemic lupus, Type 1 diabetes and celiac disease increases your risk

• excessive iodine intake and radiation exposure may also increase risk in people who are already genetically at greater risk.

What are the long-term risks?

Long-term, untreated Hashimoto’s thyroiditis can cause heart issues, higher cholesterol levels, nerve damage (peripheral neuropathy), reduced cognition and infertility.

In pregnancy, Hashimoto’s has a higher risk of pre-eclampsia (high blood pressure affecting several organs), premature birth, placental abruption (when the placenta separates from the inner wall of the uterus before birth) and, in severe cases, pregnancy loss.

The disease has also been linked with an increased risk (but low incidence) of the lymphocytes of the thyroid turning into cancer cells to cause thyroid lymphoma.

How is Hashimoto’s diagnosed?

Diagnosis can be confirmed with a blood test to check thyroid levels and antibodies.

Thyroid peroxidase antibodies are commonly present but about 5% of patients test antibody-negative. In those people, diagnosis depends on the thyroid levels, clinical presentation and ultrasound appearance of general inflammation. An ultrasound may not be required though, especially if the diagnosis is obvious.

Three hormone levels are tested to determine if you have Hashimoto’s.

Thyroid stimulating hormone (TSH) is produced by the brain to speak to the thyroid, telling it to produce two types of thyroid hormones – T3 and T4.

If you have either relative or absolute thyroid hormone deficiency, a test will show the stimulating hormones as high because the brain is trying to get the thyroid to work harder.

Can it be treated?

The management of Hashimoto’s depends on the severity of the thyroid levels. Up to 20% of the population can have antibodies but normal thyroid levels. This is still Hashimoto’s thyroid disease, but it is very mild and does not require treatment. There is no current treatment to reduce antibody levels alone.

Because thyroid peroxidase antibodies increase the risk of abnormal thyroid levels in the future, regular thyroid testing is recommended.

When the thyroid stimulating hormone is high with normal thyroid hormone levels it is termed “subclinical hypothyroidism”. When it is paired with low hormone levels it is called “overt hypothyroidism”. The first is a mild form of the disease and treatment depends on the degree of stimulating hormone elevation.

Overt hypothyroidism warrants treatment. The main form of this is thyroid hormone replacement therapy (levothyroxine) with the dose of the drug adjusted until thyroid levels are within the normal range. This is usually a lifelong treatment but, once the dose is optimised, hormone levels usually remain relatively stable.

In some people with very enlarged thyroid glands causing compressive symptoms (such as difficulty swallowing or breathing), thyroidectomy (surgical removal of the thyroid) is considered.

Hashimoto’s thyroiditis is a common condition caused by your body’s immune system incorrectly damaging to your thyroid and can go undetected. Long-term, untreated, it can cause issues with your heart, cognition, and fertility. It can be diagnosed with a simple blood test. Speak to your doctor if you have any concerns as early diagnosis and treatment can help prevent complications.

Aakansha Zala, The University of Queensland

This article is republished from The Conversation under a Creative Commons license. Read the original article.