Every organ in a mother's body changes during pregnancy

Pregnancy causes a woman's blood volume to increase by up to 50%

This change, to support the developing fetus, puts stress on the heart and blood vessels. A pregnant woman's heart rate also increases as she pumps more blood each minute to support fetal growth.

Explore how the placenta acts as lungs, kidneys, and more in the womb

This temporary organ, formed from maternal and embryonic tissue, ultimately attaches to a fetus via the umbilical cord. It transports nutrients, oxygen, antibodies, and more from the mother to the developing fetus. It also carries carbon dioxide and waste away from the fetus. The placenta—which forms only during pregnancy—is expelled during childbirth, or it needs to be removed to prevent toxic maternal infections and extreme blood loss.

How women grow tiny humans inside of them

Pregnancy is a complex biological journey, lasting about 40 weeks. When a sperm fertilizes an egg, that event triggers intricate cellular and hormonal processes, driven by hardwired cellular instructions, which lead to cell division, differentiation, and development—ultimately culminating in the birth of a baby.

Your feet can expand—permanently—due to pregnancy

A hormone called relaxin loosens tissues in the body to allow them to expand during pregnancy, affecting muscles and body parts—including the feet. The structural changes that occur in the foot as it expands are sometimes permanent. This article states that researchers have found as many as 61% of new moms did not have their foot sizes return to their prepregnant state. (Some users may encounter a paywall.)

A pregnant woman's brain sheds gray matter, perhaps explaining 'baby brain'

The brain areas involved in processing information and emotions decrease by an average of almost 5% during pregnancy. Researchers discovered in a 2025 study that this mostly temporary change—the brain hadn't fully returned to its normal size six months after pregnancy—seems to be associated with self-reported improved bonding and less hostility toward the child postpartum.

Heightened sense of smell during pregnancy is not yet well understood

Boosted smell powers and strong reactions to them are often reported beginning around the six-week mark of pregnancy. Researchers say hormonal changes likely play a role, but the change remains poorly understood.

Nasal congestion is a common side effect of pregnancy, called pregnancy rhinitis

In one recent study, almost 100% of pregnant women experienced this condition in their third trimester. The congestion is likely due to hormonal changes and neurophysiological factors, and it may also worsen at night due to circadian factors and gravitational redistribution when lying down. Treatments include saline nasal irrigation and the use of nasal strips to widen the nasal valve area.

Modern pregnancy tests detect a specific hormone in a woman's urine or blood

They pick up human chorionic gonadotropin, in either blood or urine. The hormone is produced by a woman's reproductive tissues during pregnancy.

Gestational diabetes occurs when the body can't produce insulin during pregnancy

Globally, pregnant people are increasingly at risk to develop gestational diabetes due to rising maternal ages and obesity rates. The condition is associated with heavier fetal weight, congenital abnormalities, and perinatal mortality, which includes stillbirths and deaths of babies younger than 7 days old.

'Menobelly' is real, with more fat stored around the abdomen as estrogen levels drop

The way fat is carried in the body shifts with menopause, with those pounds increasingly settling around the abdomen instead of the hips and thighs. Exacerbating this phenomenon, muscle mass also begins to decline, so calories stick around longer than usual. Resistance training, including push-ups and planks, alongside a heavier protein diet can help.

The syncytiotrophoblast is the outer layer of the placenta and the largest human cell, spanning an area about twice that of a king-sized bedsheet.

Eating competitions can ruin a stomach's elasticity

Competitive eaters make room for all that food by toying with the stomach's ability to expand and contract. Still, doctors warn that repeated stress can destroy that ability, leading to further issues.

How water pressure affects the body

The extreme conditions of the deep sea include increasing amounts of pressure as explorers and organisms descend into its depths. The major danger for both fish and humans is the way pressure changes how body tissues absorb chemical molecules...

Which organs can you live without?

While there are some organs (such as the heart) that people simply can’t live without, there are other organs that can be removed without a huge impact. Patients who have their appendix removed, for example, experience no changes to their daily...

How stress affects every organ in the body

If you are a visual learner, this resource is for you. Not only does this article from the World Economic Forum outline the causes of modern stress along with helpful strategies, but they have created an approachable infographic to show exactly how stress manifests throughout our different bodily systems. Pair this visual guide with our other resources to gain a deep knowledge of stress and the human body.

How the microbiome affects your health

The gut microbiome is so influential to overall human health that some researchers consider it a separate organ. Its conditions, influenced by environmental and lifestyle factors such as medication and exercise, contribute to immunity, metabolism, inflammation, medical treatment efficacy, brain development and function, and the development of disorders and diseases, including asthma, depression, inflammatory bowel disease, and Alzheimer's.

Why pregnant teachers were banned from classrooms

Until the 1970s, many schools required pregnant teachers to leave the classroom by mid-term. In 1974, the Supreme Court ruled these policies unconstitutional, establishing that women could choose to keep working while pregnant.

How does food move through the body?

Food passes through the digestive system via muscle movement known as peristalsis, during which a rippling contraction slowly pushes content through tubular organs, such as the esophagus and intestines. This is similar to what happens when one squeezes a tube of toothpaste, contracting the tube behind the content and forcing the tube in front of the content to expand, allowing the content to move forward.

The human body in 3D

Zygote Body is a free human anatomy tool that allows users to explore the intricacies of the human body in stunning detail. With the click of a mouse, users can isolate by body system or view anatomical structures from any angle. Check out this...

Why breathing helium, sulfur hexafluoride, and other gases changes your voice

The speed of sound varies depending on the properties of the material it travels through, including its density. Because helium is less dense than air, sound travels faster, altering the timbre of one's voice to be squeakier by enhancing its higher frequencies. In molecules that are heavier than air, low-frequency sounds are enhanced, producing a deeper voice.

The human body relaxes upon death, including the bowel and bladder, expelling urine and feces

Watch a hospice nurse walk through how death affects the human body and what to expect in the hours and days following the death of a loved one as the body breaks down.

Inhalers dilate airways and reduce inflammation

People with asthma suffer from constricted airways in their lungs, whether from muscle pressure, mucus buildup, or inflammation. Inhalers help people breathe medicine directly into their lungs to immediately relieve these symptoms.

Calculate the salary of a mother's work

While traditional parenting roles are changing, mothers do a ton of work at home, from cleaning and cooking to managing household finances. This quick calculator estimates the salary a mother (or caregiver) should receive based on number of...

Drugs in space: the pharmacy orbiting the Earth

Researchers are developing pharmaceutical solutions for astronauts, whose bodies may not respond the same way in space as they would on Earth. Similar to how microgravity causes changes to astronaut physiology, the environmental shift enables new...

Danish moms have a built-in support group through the healthcare system

Local Danish health departments put these groups together, assigning mothers into small support groups comprised of mothers in roughly the same area who gave birth around the same time. The purpose of the groups is to create a supportive network of new parents who can benefit from one another's experiences. The group's mothers decide how often to meet and what to discuss.

Circadian rhythms shift as we age—making older adults want to go to bed earlier

Throughout our lives our internal biological clocks shift. Early-to-rise toddlers become hard-to-wake teens and eventually early-to-sleep seniors. Circadian rhythm fluctuations throughout our life cycle explain some of these changes.

Alzheimer's can lead to brain shrinkage, with an average of around 2% of volume reduction per year

Learn how your body is, scientifically, like a firework with its own slow, controlled burn.

The hormonal disorder PCOS was renamed PMOS in 2026, a move designed to improve care and research by shifting the focus to the hormonal causes of this condition that affects 1 in 8 women.

Poison ivy will likely become both larger and more resilient due to climate change.

Larger animals like giraffes, elephants, and blue whales have developed a unique defense against cancer, a phenomenon known as Peto's Paradox

While the sun's gravity keeps the planets in orbit, their gravity also pulls on the sun, causing it and everything else in the solar system to orbit around a mutual balance point called the barycenter—the true center of the solar system.

Watch what the Ebola virus does inside our cells and organs in order to spread and survive.

Bone marrow (soft tissue found inside certain bones) generates roughly 500 billion new blood cells each day

After 25 people used virtual reality headsets to practice flying with virtual wings—flapping their arms—their visual cortex responded to the wings almost as if they were real arms, treating them as body parts.

In recent years a child anxiety expert has created and tested a novel phobia and anxiety treatment approach for children, focused on changing how parents respond to the fears.

Studies suggest when you sleep is as important as how much you get, and syncing with your circadian rhythms may lead to less fatigue and improved long-term health outcomes

The boiling temperature of water decreases with increasing elevation because the molecules need less energy to overcome the lower atmospheric pressure associated with thinner air.

The power and influence of the American presidency have expanded significantly over time—far beyond what the founders envisioned.

Hookworm infection, though risky, may help fight certain autoimmune conditions by tamping down the immune system's inflammatory response.

About 2,000 US babies are born annually without some portion of their limbs, potentially leading to a lifetime of pricey prosthetics.

Take a 3D tour of the Hajj, Islam's annual pilgrimage to Mecca, undertaken by over 1.5 million Muslims.

US housing costs have risen by roughly 175% between 1991 and 2026—but a growing number of Gen Zers are becoming homeowners anyway. In 2025, 4% of homebuyers were Gen Z, up from 3% the year before.

To reduce wrinkles in clothing, research recommends gentle wash cycles with more water and tumble drying with smaller loads and longer times.

Explore the archaeological treasures of Pompeii, the city buried under volcanic ash when Mount Vesuvius erupted in 79 CE.

While El Niño moves warm Pacific Ocean waters east along the equator, La Niña moves them west, shifting where rainfall will become more common for months.

An initial public offering or 'IPO' is the process of a private company becoming public by putting shares of the company on the stock market for purchase.

Fish populations in the Great Barrier Reef have increased after installing waterproof speakers on the ocean floor that played recordings of sounds from healthy coral reefs.

American dance legend Martha Graham, sometimes called 'the Picasso of dance,' refused to perform at the 1936 Olympics in Berlin and conceived the piece 'Chronicle' in response to the experience.

Salvador Dalí believed he was his own dead brother, who had died nine months before he was born