Mobile Menu

Genetics Unzipped podcast: Baby boom – the surprising genetic secrets hidden in the placenta

In the latest episode of Genetics Unzipped, presenter Dr Kat Arney explores the science behind one of the most remarkable but often overlooked organs in the mammalian body: the placenta.

Grown from scratch and then disposed of in a matter of months, the placenta is an essential part of growing a baby, forming the interface between mother and foetus for the exchange of oxygen and nutrients inside the womb. But beyond this functional role, we still know little about what else the placenta might be up to.

Helpful hormones

Professor Ros John’s research in the PREGLab at Cardiff University focuses on understanding maternal mental health, imprinted genes and the role of the placenta during pregnancy and even beyond, with big implications for the health of mother and child. In particular, she’s focusing on the role played by the hormones produced by the placenta.

Although these hormones are important for controlling foetal growth, Ros and her team have found that they have another important but less well-known role through their actions on the mother’s brain.

“Imagine if I rushed into your room at 3am in the morning screaming my head off covered in excrement, that’s what a new mother has to do that every single night for the first few months,” Ros says. “During pregnancy these hormones are helping the new mother adapt in order to take on this role of caring for her very vulnerable newborn infant.”

Building on this work, Ros’ research is now shedding light on the roots of the poorly recognised condition pre-natal depression, which can have a significant impact on maternal and child health.

A genetic dumpster fire

The placenta is a transient organ grown from cells that split off from the embryo early in development. And as Sam Behjati, a group leader at the Wellcome Sanger Institute, recently discovered with his collaborators Professors Steve Charnock-Jones and Gordon Smith, it’s an absolute genetic dumpster fire in there.

“The really exciting bit which we did not expect to find, which completely blew off our socks, is that when we looked at each of the mutations of each piece of placenta, they really looked like tumours,” Sam explains. “When we looked at the placental tissues, what we found is that the number of mutations was incredibly high. We ended up with mutational burdens that are very, very similar, in fact higher than most childhood cancers, which is quite extraordinary.”

Get the full story from the Genetics Unzipped podcast

Listen now wherever you find your podcasts or catch up on all our episodes, including show notes and full transcripts, at

Genetics Unzipped is the podcast from the UK Genetics Society, presented by award-winning science communicator Dr Kat Arney and produced by First Create the Media.  Follow Genetics Unzipped on Twitter @geneticsunzip, and the Genetics Society at @GenSocUK

Find Genetics Unzipped on Apple PodcastsGoogle Play, Spotify, or wherever you get your podcasts.

More on these topics

Genetics Unzipped / Placenta / Podcast