Good morning. It's Wednesday, April 22. Welcome to this week's Health & Medicine newsletter. Was this forwarded to you? Sign up here or click here to share with friends. |
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This week, let's dive into how we make babies! We'll first explore pregnancy—including my favorite fact of the week (see below) about the surprisingly effective pregnancy tests used in ancient Egypt. We'll then move to in vitro fertilization, examining how and why this reproductive technology has led to more than 10 million babies worldwide. Finally, we'll cover the "3-parent-baby" reproductive assistance technique—formally called mitochondrial replacement therapy—that has snagged headlines in recent years. We'll explain the nitty-gritty details of this approach, its relationship to IVF, why scientists think it could help sidestep certain inherited diseases, and much more.
As always, I'm excited to hear from you. You can just click "reply" to this email and type me a message.
—Dina Fine Maron, 1440 Health & Medicine Section Editor |
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Pregnancy, explained
Pregnancy is the roughly 280-day journey from conception to birth that powers the continuation of the human species. After sperm meets egg, and the resulting blastocyst embeds in the uterine lining, the human body undergoes significant physiological changes to support the growth and development of this cluster of cells, enabling it to become an embryo and then a fetus.
Pregnancy triggers changes to every organ in a pregnant person's body. As the uterus expands, abdominal organs shift; the heart increases blood production; feet may grow larger; and brain areas heavily involved in processing information and emotions shrink by an average of 5%. Along the way, some women experience symptoms including nausea, mood swings, heightened sense of smell, congestion, and shortness of breath. In 2023, roughly 3.6 million babies were born in the United States.
In the US, miscarriage is the most common complication of pregnancy, occurring in as many as 20% of pregnancies—or roughly 1,000,000 cases annually. There are also around 21,000 stillbirths each year, and the same number of deaths during an infant's first year of life.
Explore everything else we've found on Pregnancy.
Also, check out ...
> Explore how the placenta acts as lungs, kidneys, and more in the womb. (Watch)
> Your feet can expand—permanently—due to pregnancy. (Read)
> Ancient Egyptians developed the first pregnancy test, and scientists found it was surprisingly accurate when they tested it in the 1960s. (Read)
> Only about 0.0001% of sperm successfully reach the uterine cavity, on average. (Watch) |
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In vitro fertilization 101
In vitro fertilization is a method of fertilizing a woman's egg cells outside the human body in a laboratory setting. Also called IVF, this approach can be used to treat infertility or provide options for individuals trying to avoid passing on genetic disorders to their children.
In 2022, roughly 250,000 US patients accessed assisted reproductive technologies—most commonly IVF—resulting in more than 98,000 infants. That count represents about 2.6% of all the babies born in the US that year. Globally, over 10 million children have been conceived using the technology since it became available.
Today, costs for a single cycle of IVF can range from $15K to $30K, with many families paying out of pocket. The average number of cycles to induce pregnancy is 2.5, leaving the procedure out of reach for low-income families. IVF isn't usually covered by insurance and is primarily used by white patients and those with higher education levels who are more likely to have higher income levels.
Explore everything else we've found on In Vitro Fertilization.
Also, check out ...
> Calculate your chance of success for IVF treatments. (Read)
> Scientists first observed a sperm and an egg uniting in 1876. (Read)
> Follow an IVF procedure from lab to transplant. (Watch)
> Explore this interactive visualization of the IVF journey, as a parent or child. (Read) |
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What's mitochondrial replacement therapy?
Mitochondrial replacement therapy—which first led to a healthy child's birth in 2016—aims to help parents avoid rare mitochondrial diseases passed from mother to child by eliminating a mother's faulty mitochondrial DNA. It swaps in the mitochondrial DNA of an unaffected female donor either before or after fertilization. This lab-based approach has also garnered interest for infertility, since dysfunctional mitochondria may be a factor in female infertility.
Sometimes referred to as "three-parent IVF" because it's a modified in vitro fertilization process, this reproductive technique creates an embryo by integrating genetic material from a mother, a father, and a mitochondrial DNA donor. The donor's egg is tapped for this process, but it will contain the nuclear DNA of the biological mother.
Although almost all our genes reside in the nucleus of our cells, a tiny portion—37 genes—reside in mitochondria, the powerhouse of cells, and mitochondrial DNA, or mtDNA, is almost always passed along the maternal line, from mother to offspring. There are several hundred mitochondrial diseases in which the mitochondria do not perform as expected, affecting between 1,000 and 4,000 kids in the US each year.
Healthy babies have already been born using this approach, including eight in the UK. But recent research suggests that faulty mitochondrial DNA may sometimes persist after this intervention, even if almost all the mother's mitochondrial DNA is removed. That faulty DNA, even in tiny amounts, can potentially result in babies or future generations at risk of developing severe mitochondrial diseases, including ones that are fatal or cause severe organ damage.
Explore everything else we've found on Mitochondrial Replacement Therapy.
Also, check out ...
> Rodent evidence is mounting that dysfunctional mitochondria may be a cause of Parkinson's. (Read)
> Australia legalized three-parent IVF in 2022, after the UK. (Watch)
> Mitochondrial DNA swapping can occur before or after fertilization. (Read)
> IVF was long considered controversial and ethically dubious. (Read)
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Medical Developments Spotlight |
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We love spending time learning about the latest medical breakthroughs and spotlighting research that piques our interest, may influence future research directions, or inform healthcare conversations. Here's what we found this week.
> All the nerves of the clitoris have now been mapped in 3D
Live Science | Lauren Schneider. New high-resolution mapping of the human clitoris, the structure responsible for female pleasure, offers an unprecedented look at the clitoral nerves, in 3D. The findings, published on a preprint server, haven't yet been peer-reviewed. Study authors hope the new work may help surgeons avoid damaging nerves in the genital area and also improve reconstructive procedures for patients with female genital mutilation. (Read)
> Two experimental lung cancer drugs showing promise in early data
WSJ | Xavier Martinez. Over the weekend, researchers at a San Diego-based cancer conference presented exciting early results from clinical trials of two experimental drugs that may treat lung cancer. The drugs each target the KRAS gene, a common driver of human cancers, and both slowed disease progression and shrank tumors that had proved resistant to chemotherapy and immunotherapy. (Read | More on Cancer)
> Severe malaria may cause long-term brain damage
Science | Gretchen Vogel. A study that tracked nearly 1000 children in Uganda for as long as 15 years post-malaria infection concluded that both cerebral malaria and a malaria complication—severe anemia—were linked to worse cognitive and math scores for many years after infection. (Read | More on Malaria) |
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"After years of uncertainty, this treatment gave us hope—and then it gave us a baby." |
—A mother of one of the 8 healthy UK babies born via mitochondrial replacement therapy |
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