The EMERALD Study

What is the EMERALD Study?

The EMERALD study is a clinical trial that is exploring the potential of an investigative medicine to help pregnant women suffering from severe nausea and vomiting, known as hyperemesis gravidarum (HG).

HG can lead to significant weight loss, multiple hospital admissions and other pregnancy complications, including fetal growth problems and earlier delivery (preterm delivery).

Currently, there are limited treatments available for HG. This trial will test NGM120, a monoclonal antibody, to see if it is safe and effective for treating HG.

This study is funded by NGM Biopharmaceuticals (USA).

What is Pregnancy Sickness Support’s involvement in the EMERALD Study?

Pregnancy Sickness Support (PSS) is the lead Patient and Public Involvement (PPI) partner in the UK for the EMERALD Study — a clinical trial evaluating a potential new treatment for Hyperemesis Gravidarum (HG).

As lead PPI partner, PSS ensures that the voices, needs, and lived experiences of those affected by HG are embedded throughout the trial — from design through to completion. We work closely with the NGM Bio team to shape how the study is developed, how information is shared, and how participants’ perspectives are reflected.

PSS is not responsible for running the clinical trial or for managing participants who may choose to take part after hearing about it from us. Our role is to advocate for the HG community within the research process and to support efforts to develop safe, effective treatment options based on their needs.

“Pregnancy Sickness Support is proud to be the lead patient and public involvement partner for the EMERALD Study. It’s incredibly encouraging to see such a significant clinical trial for Hyperemesis Gravidarum taking place here in the UK. Including pregnant women in research is vital — not only to ensure they benefit from scientific progress, but to drive forward the development of safe, effective, and innovative treatment options for the future.”

Charlotte Howden

CEO, Pregnancy Sickness Support

How can you participate?

For more information about the EMERALD Study, please click on the button at the top of this page or visit the UK’s Clinical Study Register listing here.

Please note: The PSS–NGM Bio PPI HQ team does not have access to any additional information beyond what is provided in the clinical trial listing. We are not involved in the clinical delivery of the trial and are therefore unable to respond to individual enquiries about eligibility, participation, or trial sites. For all questions about taking part, please refer directly to the contact details in the study listing.

However, below are some general questions we believe many people may have — and which we’re able to answer.

Who can participate in the trial?

Pregnant women aged 18 to 45 years who are experiencing severe nausea and vomiting between 9 and less than 17 weeks of pregnancy.

If I am not currently pregnant can I enquire about the trial?

The EMERALD Study is only open to participants who are currently pregnant and meet the eligibility criteria outlined in the clinical trial listing. If you are not currently pregnant, you will not be able to take part at this time. However, you are still very welcome to review the listing and follow the study’s progress and contact your nearest Study Participating Centre should your position change.

How long is the study expected to run for?

The study is expected to enroll through to the end of December 2025.

Why should I consider the EMERALD study for my HG?

Although it is unclear how HG develops, one possible explanation is that an increase of a hormone called Growth Differentiation Factor-15 or GDF15, most of which comes from the placenta and fetus during pregnancy, causes the nausea and vomiting and HG.

Although GDF15 is a hormone that everyone has in their blood, the levels of GDF15 are higher in pregnant women, and even higher in HG. Medicines to treat HG are limited.

The human body naturally makes antibodies. An antibody is a protein that binds to and helps the body remove foreign objects like bacteria. Or it can stick to and inactivate compounds.

NGM120 is a monoclonal antibody designed to stick to the receptor for GDF15. It is hoped that, by sticking to the GDF15 receptor and inactivating it, NGM120 will improve HG symptoms, such as nausea and vomiting.

NGM120 is being investigated for its safety and effectiveness for the potential treatment of HG in the EMERALD study.

Is NGM120 going to harm my baby?

NGM120 has been studied in pregnant animals with no side effects noted to the growing fetuses during pregnancy or any birth defects related to NGM120.

The babies of the pregnant animals had detectable NGM120 in their blood, which was expected since antibodies of this type cross the placenta from mom to baby. The babies were healthy, grew to maturity, and were able to have babies of their own.

While these observations in animals are reassuring, NGM120 may have some risks and side effects in pregnant women that are unknown at this time. Your study doctor can discuss your specific risks in more detail.

It is worth noting that medications of the same type (monoclonal antibodies) have been used in pregnancy for patients with long term conditions such as rheumatoid arthritis and Crohn’s disease. So, whilst NGM120 has not been specifically tested in pregnant women, there is a lot of evidence available supporting the use of monoclonal antibodies in pregnancy.

Can I enquire about the trial before 9 weeks or after 16 weeks of pregnancy?

If you are less than 9 weeks pregnant and are suffering from severe nausea and vomiting in pregnancy, you can enquire about the trial. This is because it can take several weeks to enrol in the trial.

If you are 17 weeks pregnant or more, you will not be eligible to take part in this trial.
This is because the EMERALD Study is focused on treating Hyperemesis Gravidarum (HG) in its earlier stages, specifically between 9 and 16 weeks of pregnancy, which aligns with the 2021 Windsor Definition of HG and when it is typically most severe.

Where do I need to be located to take part?

There are currently seven Study Participating Centres (SPCs) in England.
To take part, you must be able to travel to one of these centres for four in-person visits. For the full list of locations, please click here and scroll to the bottom of the page.

Can I withdraw from the study at any time even if I sign the patient informed consent form?

You are encouraged to discuss any questions you may have about the study with your treating physician, specialist, or midwife.

You are free to change your mind to withdraw from the study at any time, even if you have signed the informed consent form.

I am concerned about taking part in the study due to the number of visits and length of the visits. Is their support provided for childcare and travel?

For screening, we have estimated that you will need to be onsite at the hospital for 3 hours. This will depend on the total number of assessments and how quickly the results come through. Other visits are likely to be shorter as they only require quick assessment such as a blood draw.

If you need to arrange childcare or travel to take part in the study, please note these costs will be reimbursed, along with any other reasonable expenses such as food and parking.

For full details about the EMERALD Study — including eligibility criteria and contact information — please refer to the UK Clinical Study Register listing here.

Pregnancy Sickness Support is not involved in the clinical delivery of the study and is unable to answer individual questions about participation. All enquiries must be directed to the study team via the official listing.

To contact PSS about this study please email office@pregnancysicknesssupport.org.uk

For support with pregnancy sickness or Hyperemesis Gravidarum (HG) contact our support team.