Pregnant at 42. Now She's Solving the Mystery of the Embryo - OZY | A Modern Media Company

Pregnant at 42. Now She's Solving the Mystery of the Embryo

Pregnant at 42. Now She's Solving the Mystery of the Embryo

By Marissa Fessenden


Because she is growing human embryos in the lab for longer than ever before.

By Marissa Fessenden

Magdalena Zernicka-Goetz was 42 and pregnant when an early test returned some chilling results: More than a third of the cells in the developing embryo carried a serious abnormality that tripled one of the chromosomes. Her doctors urged her to wait and see, but for a biologist specializing in human development, staying idle was not an option. She headed to the lab and began researching similar abnormalities in mouse embryos.

Her work revealed that the early embryo has astonishing flexibility. Cellular programs can identify and weed out abnormal cells, allowing normal cells to take over and the embryo to remain viable. “This was, to my knowledge, the first discovery of what happens to those cells,” Zernicka-Goetz says.

The experience left Zernicka-Goetz intensely curious about how a handful of cells becomes a complete person — with a brain, limbs and emotions, pushing the University of Cambridge professor to culture human embryos in the lab for nearly two weeks longer than anyone had done before. The feat was hailed by the journal Science as the “Breakthrough of the Year” in 2016. Since then, the now 54-year-old hasn’t faltered in her quest to understand the earliest stages of human development, a period when many pregnancies fail.

“We thought that if we can culture human embryos at the time, we can see how they are changing their shape, architecture and pattern of gene expression to successfully generate a human,” says Zernicka-Goetz, who was once featured for her elegant style in a Vogue listicle about the wardrobes of successful women.

I wanted to understand how cells in our embryos make decisions about their fate.

Magdalena Zernicka-Goetz 

Zernicka-Goetz’s son Szymon was born in 2007 without any complications. The fortunate outcome was never certain, but her research had helped her understand what was happening inside her own body and the bodies of other expectant mothers. “I am sure she was scared,” says friend and colleague Marianne Bronner, a biology professor at the California Institute of Technology who studies stem cells in early developing vertebrates. “The fact that she has talked about it publicly … is just a sign of how dedicated she is to helping others.”

Science has always been personal for Zernicka-Goetz. Her father was a young medical doctor when she was born in Warsaw, Poland. Short on funds, the new family was given an unused laboratory to convert into an apartment at the institute where he worked. Growing up, she was surrounded by scientists in white lab coats. “As far as I was concerned, everybody was having this type of childhood,” she recalls. Conversations with her father, who became a neurobiologist, drew her to the sciences. In college at the University of Warsaw, she attended a lecture by Andrzej Tarkowski, a renowned Polish embryologist who was the first to create chimeric mouse embryos — where cells from two embryos are fused to make one. Such fusions help researchers trace embryonic cells that give rise to organs in adults.


Zernicka-Goetz had found her path. “I wanted to understand how cells in our embryos make decisions about their fate. Those cells do not have a brain, so there is nothing that can coordinate those decisions, and yet they are very well coordinated,” she says. “I was enchanted by that process.” She would work on both her master’s and Ph.D. in Tarkowski’s lab.

Today she teaches and leads a team of researchers at Cambridge, a group that is delving deep into the workings of the early embryo. Her lab coaxes stem cells to organize and form structures that resemble embryos — a process that allows the scientists to control and query the cascade of chemical cues that direct development. They also developed a system that allows them to keep human embryos alive by incubating them in a special cocktail of nutrients and chemicals past the stage where they would need to implant in the wall of the uterus. This work revealed key changes in cell populations and structure that keep the embryo viable at that milestone, findings that may point to where the process can go awry in early pregnancy.

Magdalena Zernicka-Goetz

At first, Zernicka-Goetz’s work stirred controversy because she found molecular differences between cells when the embryo contains just four cells total. Most researchers thought these cells were all the same and looked at Zernicka-Goetz as a newcomer challenging a tenet of the field. But she was undaunted. “She just kept on track and stuck with her mission,” Bronner says, proving to critics that her research was valid and potentially far-reaching. 

By staying focused on the work and pressing against boundaries, Zernicka-Goetz hopes that her team’s findings will lead to better IVF technologies and a clearer understanding of the issues and challenges around fertility. “Magdalena has contributed some of the most important findings about early mammalian development over the last two decades,” says Nicolas Plachta, a senior researcher who images cells within growing embryos at the Institute of Molecular and Cell Biology in Singapore.

Now, Zernicka-Goetz is investigating how embryos keep track of time: What internal clock alerts them to proceed to the next stage of development? What knocks that clock off track? Asked to project further into the future, she says the questions that engage her are still taking shape. She likens her scientific process to one of her favorite hobbies: After leaving work, she likes to reflect on the day by painting, oftentimes painting over older works and creating abstract designs filled with color, patiently waiting for something to emerge.

“When I paint or look at other people’s paintings or any beautiful piece of art … that gives me ideas,” Zernicka-Goetz says. “Research is also about the process of creation because you have to come up with the idea of the experiment and then perform it. And some of the results that we have from our work are beautiful. The embryos are beautiful.”

5 Questions for Magdalena Zernicka-Goetz

What’s your favorite book? 
When I had more time to read books rather than scientific papers, I had many favorite authors. Some of the books I particularly liked were Milan Kundera’s The Unbearable Lightness of Being and Dai Sijie’s Balzac and the Little Chinese Seamstress. I remember reading the last on a plane going to give a lecture in New York, having my tears coming down and a neighbor being very concerned.

What do you worry about? 
I worry about not having enough time for my family and friends. They are most important to me, and yet I spend most of my day, every day, away from them.

What’s one thing you can’t live without? 
I would say sleep and coffee. My new ideas come when I wake up or when I have time to sit down with my first cup of coffee, so I depend on them.

Who’s your hero? 
In science, it changes. But right now, John Gurdon and Janet Rossant. In film, there are many directors I love, but to name two: Krzysztof Kieslowski and Pawel Pawlikowski (his film Ida was amazing). In sculpture, over recent years: Igor Mitoraj.

What’s one item on your bucket list? 
I would like to be granted a second life in which I won’t be a scientist who loves art but an artist who loves science.

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