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Many women in the UK are overweight before pregnancy. This can affect their children, making them more likely to have health problems such as being overweight themselves and, in the long term, having high blood pressure, diabetes and heart disease.

An increasing number of women are using weight-loss surgery or medications before pregnancy, but we do not yet know how these treatments can impact their children. Our study will investigate these effects, during pregnancy and beyond, with the ultimate aim of helping women make safer, healthier choices before having children.

I-BEGIN is a three-year study, funded by the Medical Research Council. 

Dexcom UK Limited and CW+ are contributing as project sponsors. The research team involves collaboration with international experts based in Northern Ireland and Australia.

Clinical study visits

The clinical part of the study takes place at:                                                                                   

Chelsea and Westminster Hospital, Fetal Medicine Unit, Lift Bank B, First Floor, 369 Fulham Road, London, SW10 9NH

Laboratory and analysis

The research involving the analysis of samples using metabolic phenotyping techniques is carried out at:     

Department of Metabolism, Digestion and Reproduction, 10th Floor, Commonwealth Building, Hammersmith Hospital Campus, 51³Ô¹ÏÍø, Du Cane Road, London, W12 0NN

• Women who have had bariatric surgery before getting pregnant
• Women who have taken weight-loss medications for at least three months, within the six months before getting pregnant or in early pregnancy
• Women who have not had weight-loss surgery or taken weight-loss medications before pregnancy (control group)

By taking part in the I-BEGIN study, you will receive extra visits to monitor your blood pressure and blood sugars, and extra ultrasound scans to monitor your baby’s growth. Our team will follow you up during pregnancy and advise on further steps and decisions, whenever required.

Our research will help women understand how to manage weight before pregnancy so they can give their children the best possible start. For healthier moms, healthier babies and a healthier future.

Participation is voluntary and you may withdraw from the study at any time without giving any reason.

"Being part of the PPI Group^a was one of the best parts of choosing Chelsea Hospital, and why I then repeated the experience with my second child. I built a close relationship with the team and felt accompanied and more supported than most mums that I spoke to."

- Cristina C, mum of two- February 2026

“I genuinely loved being part of the study — the extra monitoring and support made such a difference and gave me a lot of reassurance during my pregnancy. I was especially grateful for the additional glucose monitoring, and given how new GLP-1 weight loss injections are, it felt really reassuring to be part of research that is helping to better understand their impact during pregnancy. It made me feel much more supported and confident throughout. I also think the research is so important and will really help improve care for women in the future." 

-Lucinda, mum of one – March 2026

"Being part of this study has been amazing for myself, my baby and others. I felt like I was cared for extremely well and given the opportunity to follow my pregnancy in a more detailed way all whilst helping to gain more insight into the pregnancies of others who need it.”

-Antonia, mum of one – April 2026

^a Patient and Public Involvement group of I-BEGIN study.

A member of team will reach out to you and schedule the first visit.

We would like to see you five times during pregnancy . We can easily combine these visits with your regular antenatal appointments. At all these visits, which will take about 30-45mins each, we will ask questions about your health, measure your weight, height, blood pressure and ask for a blood and a urine sample. We will perform an ultrasound scan of the baby to assess its wellbeing. 

To get a better picture of your  sugar control during pregnancy, we will arrange for blood tests  and  use a wearable device, continuous glucose monitor (CGM), that will track your blood sugar levels in real-time, 24/7, using a small sensor under your skin. It sends data via Bluetooth to a smartphone or receiver, providing instant, continuous readings 

When your baby is born, we’ll take a few samples from the umbilical cord, placenta, and your baby’s urine.  We will ask for a small sample of your breastmilk.

We would like to follow your baby at 3 months, 12–24 months, and 5–10 years. Our Paediatric team will check their health, growth, and development. We will also ask for a urine and a stool sample and If you agree, a small blood sample (about a teaspoon) at some visits.

If you would like more information or are interested in taking part, please contact the study team via email on:

chelwest.i-begin@nhs.net

chelwest.researchmidwives@nhs.net

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