Understanding the Placenta and Pregnancy Complications

Plain English Summary

Pregnancy is an incredible journey, but for some families, it can come with serious complications that affect both mother and baby.

Pregnancy complications like pre-eclampsia (PE) and fetal growth restriction (FGR) can put mothers and babies at serious risk, yet they are often difficult to detect early. Current checks do not identify all women who will develop these problems. Earlier and more accurate tests could help the NHS provide better monitoring and reduce avoidable harm.

This project aims to develop a simple blood test that measures tiny fragments of genetic material called “cell-free RNAs” (cfRNAs). These come from the placenta and give a real-time picture of how the pregnancy is developing. My recent research found two cfRNAs—Leptin (LEP) and Pappalysin-2 (PAPPA2)—that are higher in pregnancies with PE and FGR. We now need to confirm these findings in a new group of women and test how well they can be measured using practical laboratory methods.

We will compare two technologies: digital PCR, which is extremely sensitive, and the NanoString nCounter, which can measure many markers at once and is already used in some clinical settings. Working with women who have experienced pregnancy complications, midwives, doctors, and NHS labs, we will explore whether this kind of test is accurate, useful, and acceptable.

Our long-term goal is to create an early warning test that helps identify pregnancies at higher risk, so that personalised care and closer monitoring can be offered. This research aims to support safer pregnancies and healthier outcomes for families.

What is the Placenta?

The placenta is a temporary organ that develops during pregnancy.
It connects the mother and baby, supplying oxygen and nutrients to the fetus and removing waste products.
Beyond being a nutrient bridge, the placenta also plays critical roles in:

Hormone production (e.g. hCG, progesterone, leptin)
Immune protection of the fetus
Regulation of fetal growth and development

When the placenta does not form or function properly, it can lead to a range of pregnancy complications.

Preeclampsia

Preeclampsia is a serious pregnancy condition characterized by high blood pressure and protein in the urine after 20 weeks of gestation.
It affects around 5–8% of pregnancies and can cause serious health problems for both mother and baby.

Key facts:

Often associated with abnormal placental development and blood flow.
May cause symptoms such as headaches, swelling, or visual changes.
In severe cases, it can lead to seizures, organ failure, or stillbirth.
The only definitive cure is delivery of the baby and placenta.

Early detection is therefore essential — and one goal of cfRNA biomarker research is to identify high-risk pregnancies before symptoms appear.

Fetal Growth Restriction (FGR)

Fetal Growth Restriction (FGR) occurs when a baby is smaller than expected for gestational age due to inadequate nutrient or oxygen supply from the placenta.

Why it matters:

FGR increases the risk of stillbirth and long-term developmental issues.
It often overlaps with preeclampsia and other placental dysfunctions.
Early identification allows closer monitoring and timely delivery when necessary.

Gestational Diabetes Mellitus (GDM)

Gestational diabetes is a type of diabetes that develops during pregnancy.
It happens when the body cannot produce enough insulin to meet the increased demands of pregnancy.

Key points:

Usually occurs in the second or third trimester.
Can cause babies to grow too large (macrosomia), leading to birth complications.
May increase the risk of preeclampsia and cesarean delivery.
Women with GDM are more likely to develop type 2 diabetes later in life.

Although GDM is primarily a metabolic disorder, it also affects placental function — highlighting how maternal metabolism and placenta health are closely linked.

Why Study Cell-free RNAs?

Cell-free RNAs (cfRNAs) are fragments of RNA released from cells into the blood.
During pregnancy, some cfRNAs originate from the placenta and can reflect how it is functioning.

By studying cfRNAs, we can:

Detect early signs of placental stress or dysfunction.
Predict complications before clinical symptoms appear.
Potentially guide personalized monitoring and interventions.

This line of research brings us closer to non-invasive prediction tools that could save lives and improve outcomes for mothers and babies.

Learn More

You can find more information and updates on the research through:

Cell-free RNAs published in Nature Communications in 2025
Placenta transcriptome paper published in Nature Communications in 2021
An interactive placenta transcriptome website

I have been involved with some previous public engagement activities such as:

--- title: "Understanding the Placenta and Pregnancy Complications" format: html: toc: true toc-depth: 2 --- ## Plain English Summary Pregnancy is an incredible journey, but for some families, it can come with serious complications that affect both mother and baby. Pregnancy complications like pre-eclampsia (PE) and fetal growth restriction (FGR) can put mothers and babies at serious risk, yet they are often difficult to detect early. Current checks do not identify all women who will develop these problems. Earlier and more accurate tests could help the NHS provide better monitoring and reduce avoidable harm. This project aims to develop a simple blood test that measures tiny fragments of genetic material called “cell-free RNAs” (cfRNAs). These come from the placenta and give a real-time picture of how the pregnancy is developing. My recent research found two cfRNAs—Leptin (***LEP***) and Pappalysin-2 (***PAPPA2***)—that are higher in pregnancies with PE and FGR. We now need to confirm these findings in a new group of women and test how well they can be measured using practical laboratory methods. We will compare two technologies: digital PCR, which is extremely sensitive, and the NanoString nCounter, which can measure many markers at once and is already used in some clinical settings. Working with women who have experienced pregnancy complications, midwives, doctors, and NHS labs, we will explore whether this kind of test is accurate, useful, and acceptable. Our long-term goal is to create an early warning test that helps identify pregnancies at higher risk, so that personalised care and closer monitoring can be offered. This research aims to support safer pregnancies and healthier outcomes for families. ## What is the Placenta? The **placenta** is a temporary organ that develops during pregnancy. It connects the mother and baby, supplying oxygen and nutrients to the fetus and removing waste products. Beyond being a nutrient bridge, the placenta also plays critical roles in: - Hormone production (e.g. hCG, progesterone, leptin) - Immune protection of the fetus - Regulation of fetal growth and development When the placenta does not form or function properly, it can lead to a range of **pregnancy complications**. ## Preeclampsia **Preeclampsia** is a serious pregnancy condition characterized by **high blood pressure** and **protein in the urine** after 20 weeks of gestation. It affects around 5–8% of pregnancies and can cause serious health problems for both mother and baby. **Key facts:** - Often associated with abnormal placental development and blood flow. - May cause symptoms such as headaches, swelling, or visual changes. - In severe cases, it can lead to **seizures**, **organ failure**, or **stillbirth**. - The only definitive cure is **delivery of the baby and placenta**. Early detection is therefore essential — and one goal of cfRNA biomarker research is to identify high-risk pregnancies **before symptoms appear**. ## Fetal Growth Restriction (FGR) **Fetal Growth Restriction (FGR)** occurs when a baby is smaller than expected for gestational age due to inadequate nutrient or oxygen supply from the placenta. **Why it matters:** - FGR increases the risk of stillbirth and long-term developmental issues. - It often overlaps with preeclampsia and other placental dysfunctions. - Early identification allows closer monitoring and timely delivery when necessary. ## Gestational Diabetes Mellitus (GDM) **Gestational diabetes** is a type of diabetes that develops during pregnancy. It happens when the body cannot produce enough insulin to meet the increased demands of pregnancy. **Key points:** - Usually occurs in the second or third trimester. - Can cause babies to grow too large (macrosomia), leading to birth complications. - May increase the risk of preeclampsia and cesarean delivery. - Women with GDM are more likely to develop type 2 diabetes later in life. Although GDM is primarily a metabolic disorder, it also affects placental function — highlighting how **maternal metabolism and placenta health are closely linked**. ## Why Study Cell-free RNAs? Cell-free RNAs (cfRNAs) are fragments of RNA released from cells into the blood. During pregnancy, some cfRNAs originate from the **placenta** and can reflect how it is functioning. By studying cfRNAs, we can: - Detect early signs of placental stress or dysfunction. - Predict complications before clinical symptoms appear. - Potentially guide personalized monitoring and interventions. This line of research brings us closer to **non-invasive prediction tools** that could save lives and improve outcomes for mothers and babies. ## Learn More You can find more information and updates on the research through: - Cell-free RNAs [**published in Nature Communications in 2025**](https://www.nature.com/articles/s41467-025-61931-7) - Placenta transcriptome paper [**published in Nature Communications in 2021**](https://www.nature.com/articles/s41467-021-22695-y) - An interactive [**placenta transcriptome website**](https://www.obgyn.cam.ac.uk/placentome/) I have been involved with some previous public engagement activities such as: - [Cambridge Festival 2021: **“Pregnancy – a nine-month phone call”**](https://obsgynaecam.github.io/CF2021/) - [Cambridge Science Festival 2020: **“It takes 3 to Tango: Key players for a successful pregnancy”**](https://sung.github.io/CamObsGynCSF2020/)