If someone’s heart suddenly stops beating, they may only have minutes to live. Doing CPR (cardiopulmonary resusciation) can increase their chances of survival. CPR makes sure blood keeps pumping, providing oxygen to the brain and vital organs until specialist treatment arrives.

But research shows bystanders are less likely to intervene to perform CPR when that person is a woman. A recent Australian study analysed 4,491 cardiac arrests between 2017–19 and found bystanders were more likely to give CPR to men (74%) than women (65%).

Could this partly be because CPR training dummies (known as manikins) don’t have breasts? Our new research looked at manikins available worldwide to train people in performing CPR and found 95% are flat-chested.

Anatomically, breasts don’t change CPR technique. But they may influence whether people attempt it – and hesitation in these crucial moments could mean the difference between life and death.

Heart health disparities

Cardiovascular diseases – including heart disease, stroke and cardiac arrest – are the leading cause of death for women across the world.

But if a woman has a cardiac arrest outside hospital (meaning her heart stops pumping properly), she is 10% less likely to receive CPR than a man. Women are also less likely to survive CPR and more likely to have brain damage following cardiac arrests.

These are just some of many unequal health outcomes women experience, along with transgender and non-binary people. Compared to men, their symptoms are more likely to be dismissed or misdiagnosed, or it may take longer for them to receive a diagnosis.

Bystander reluctance

There is also increasing evidence women are less likely to receive CPR compared to men.

This may be partly due to bystander concerns they’ll be accused of sexual harassment, worry they might cause damage (in some cases based on a perception women are more “frail”) and discomfort about touching a woman’s breast.

Bystanders may also have trouble recognising a woman is experiencing a cardiac arrest.

Even in simulations of scenarios, researchers have found those who intervened were less likely to remove a woman’s clothing to prepare for resuscitation, compared to men. And women were less likely to receive CPR or defibrillation (an electric charge to restart the heart) – even when the training was an online game that didn’t involve touching anyone.

There is evidence that how people act in resuscitation training scenarios mirrors what they do in real emergencies. This means it’s vital to train people to recognise a cardiac arrest and be prepared to intervene, across genders and body types.

Skewed to male bodies

Most CPR training resources feature male bodies, or don’t specify a sex. If the bodies don’t have breasts, it implies a male default.

For example, a 2022 study looking at CPR training across North, Central and South America, found most manikins available were white (88%), male (94%) and lean (99%).

These studies reflect what we see in our own work, training other health practitioners to do CPR. We have noticed all the manikins available to for training are flat-chested. One of us (Rebecca) found it difficult to find any training manikins with breasts.

A single manikin with breasts

Our new research investigated what CPR manikins are available and how diverse they are. We identified 20 CPR manikins on the global market in 2023. Manikins are usually a torso with a head and no arms.

Of the 20 available, five (25%) were sold as “female” – but only one of these had breasts. That means 95% of available CPR training manikins were flat-chested.

We also looked at other features of diversity, including skin tone and larger bodies. We found 65% had more than one skin tone available, but just one was a larger size body. More research is needed on how these aspects affect bystanders in giving CPR.

Breasts don’t change CPR technique

CPR technique doesn’t change when someone has breasts. The barriers are cultural. And while you might feel uncomfortable, starting CPR as soon as possible could save a life.

Signs someone might need CPR include not breathing properly or at all, or not responding to you.

To perform effective CPR, you should:

• put the heel of your hand on the middle of their chest
• put your other hand on the top of the first hand, and interlock fingers (keep your arms straight)
• press down hard, to a depth of about 5cm before releasing
• push the chest at a rate of 100-120 beats per minute (you can sing a song) in your head to help keep time!)

https://www.youtube.com/embed/Plse2FOkV4Q?wmode=transparent&start=94 An example of how to do CPR – with a flat-chested manikin.

What about a defibrillator?

You don’t need to remove someone’s bra to perform CPR. But you may need to if a defibrillator is required.

A defibrillator is a device that applies an electric charge to restore the heartbeat. A bra with an underwire could cause a slight burn to the skin when the debrillator’s pads apply the electric charge. But if you can’t remove the bra, don’t let it delay care.

What should change?

Our research highlights the need for a range of CPR training manikins with breasts, as well as different body sizes.

Training resources need to better prepare people to intervene and perform CPR on people with breasts. We also need greater education about women’s risk of getting and dying from heart-related diseases.

Jessica Stokes-Parish, Assistant Professor in Medicine, Bond University and Rebecca A. Szabo, Honorary Senior Lecturer in Critical Care and Obstetrics, Gynaecology and Newborn Health, The University of Melbourne

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

Head hair comes in many colours, shapes and sizes, and hairstyles are often an expression of personal style or cultural identity.

Many different genes determine our hair texture, thickness and colour. But some people’s hair changes around the time of puberty, pregnancy or after chemotherapy.

So, what can cause hair to become curlier, thicker, thinner or grey?

Curly or straight? How hair follicle shape plays a role

Hair is made of keratin, a strong and insoluble protein. Each hair strand grows from its own hair follicle that extends deep into the skin.

Curly hair forms due to asymmetry of both the hair follicle and the keratin in the hair.

Follicles that produce curly hair are asymmetrical and curved and lie at an angle to the surface of the skin. This kinks the hair as it first grows.

The asymmetry of the hair follicle also causes the keratin to bunch up on one side of the hair strand. This pulls parts of the hair strand closer together into a curl, which maintains the curl as the hair continues to grow.

Follicles that are symmetrical, round and perpendicular to the skin surface produce straight hair.

Life changes, hair changes

Our hair undergoes repeated cycles throughout life, with different stages of growth and loss.

Each hair follicle contains stem cells, which multiply and grow into a hair strand.

Head hairs spend most of their time in the growth phase, which can last for several years. This is why head hair can grow so long.

Let’s look at the life of a single hair strand. After the growth phase is a transitional phase of about two weeks, where the hair strand stops growing. This is followed by a resting phase where the hair remains in the follicle for a few months before it naturally falls out.

The hair follicle remains in the skin and the stems cells grow a new hair to repeat the cycle.

Each hair on the scalp is replaced every three to five years.

Hormone changes during and after pregnancy alter the usual hair cycle

Many women notice their hair is thicker during pregnancy.

During pregnancy, high levels of oestrogen, progesterone and prolactin prolong the resting phase of the hair cycle. This means the hair stays in the hair follicle for longer, with less hair loss.

A drop in hormones a few months after delivery causes increased hair loss. This is due to all the hairs that remained in the resting phase during pregnancy falling out in a fairly synchronised way.

Hair can change around puberty, pregnancy or after chemotherapy

This is related to the genetics of hair shape, which is an example of incomplete dominance.

Incomplete dominance is when there is a middle version of a trait. For hair, we have curly hair and straight hair genes. But when someone has one curly hair gene and one straight hair gene, they can have wavy hair.

Hormonal changes that occur around puberty and pregnancy can affect the function of genes. This can cause the curly hair gene of someone with wavy hair to become more active. This can change their hair from wavy to curly.

Researchers have identified that activating specific genes can change hair in pigs from straight to curly.

Chemotherapy has very visible effects on hair. Chemotherapy kills rapidly dividing cells, including hair follicles, which causes hair loss. Chemotherapy can also have genetic effects that influence hair follicle shape. This can cause hair to regrow with a different shape for the first few cycles of hair regrowth.

Hormonal changes as we age also affect our hair

Throughout life, thyroid hormones are essential for production of keratin. Low levels of thyroid hormones can cause dry and brittle hair.

Oestrogen and androgens also regulate hair growth and loss, particularly as we age.

Balding in males is due to higher levels of androgens. In particular, high dihydrotestosterone (sometimes shortened to DHT), which is produced in the body from testosterone, has a role in male pattern baldness.

Some women experience female pattern hair loss. This is caused by a combination of genetic factors plus lower levels of oestrogen and higher androgens after menopause. The hair follicles become smaller and smaller until they no longer produce hairs.

Reduced function of the cells that produce melanin (the pigment that gives our hair colour) is what causes greying.

Theresa Larkin, Associate professor of Medical Sciences, University of Wollongong

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