A new tool to understand pregnancy risks in women with chronic kidney disease
New results published in Kidney International reports, led by Dr Kate Bramham from King's College London with Kidney Research UK funding, showed the benefits of a pregnancy-specific risk prediction tool that estimates the likelihood of kidney complications for women with chronic kidney disease, helping support more personalised pregnancy counselling.
Balancing pregnancy and risk of CKD progression
Women living with chronic kidney disease (CKD) who are planning a pregnancy often face difficult conversations. Doctors know that CKD can increase risks for both mother and baby, but it has been hard to give clear, personalised answers about what those risks look like for each woman.
In this study, Kate and the team set out to change that by developing a tool that can better estimate these risks before pregnancy begins. The tool estimated two important risks:
- Risk to the mother's kidneys: including significant kidney function decline after pregnancy or needing dialysis/transplant-related treatment.
- Risk to the baby: including being born small or prematurely (before 34 weeks).
Dr Kate Bramham commented:"From the very beginning, we worked with women living with CKD to understand what questions they wanted answered. They wanted to know not only about their own kidneys, but also about the wellbeing of their baby. That's why we designed the tool around the outcomes that matter most to women and their families."
Building and testing the pregnancy risk tool using real-world data
Kate and the team used data from several large UK health databases, linking kidney registries and hospital records to build a detailed picture of women’s health before and during pregnancy.
They included women with reduced kidney function in the two years before pregnancy who gave birth between 1997 and 2021, allowing them to analyse thousands of real-world pregnancies over more than two decades.
The tool was developed using data from 746 women with CKD and then tested in much larger groups, including nearly 7,000 women in one cohort and a further 380 in another, with additional checks using Canadian data.
The team selected known risk factors such as kidney function and blood pressure and worked with people living with CKD to agree which outcomes mattered most. This helped ensure the tool reflects real-life concerns in pregnancy planning and care.
Helping women with CKD plan pregnancy with greater confidence
The tool performed well when tested in women with CKD in both the UK and Canada. It was particularly good at identifying women who were unlikely to experience serious complications during or after pregnancy. This could help give doctors greater confidence when reassuring women they are at lower risk, while also highlighting those who may need closer monitoring and specialist care.
Dr Mairéad Hamill, renal trainee at King’s College London, supervised by Kate, said: "One of the most important findings from this study is that many women with chronic kidney disease have positive pregnancy outcomes. Around 70% of women did not experience significant kidney function loss after pregnancy, and most babies were born at a healthy stage of pregnancy. We hope this tool will allow us to reassure more women that they are likely to have a successful pregnancy, while identifying those who need extra support."
The study also showed that pregnancy requires a different approach to risk assessment. When compared with an existing kidney disease risk calculator, the standard tool often underestimated pregnancy-related risks because it was designed for CKD in general, rather than pregnancy specifically. This highlights the importance of using pregnancy-specific tools when supporting women and families.
What could this mean for pregnancy and CKD?
By providing personalised estimates of risk before pregnancy, this tool could support more informed conversations between women and their healthcare teams, helping them make decisions that are right for them. This more personalised approach has the potential to make pregnancy counselling more balanced, empowering and tailored to each woman's individual circumstances.
Real-life impact
This research focuses on improving how we understand pregnancy risk in women with CKD. While every experience is different, some families do face serious complications during pregnancy.
Read one mum’s story about her experience of kidney failure during pregnancy and the impact it had on her family.
What's next for this research?
"This is just the beginning. As we continue to collect data through the study, we will be able to improve the accuracy of the tool and answer important questions for women with rarer kidney diseases, where there is currently very little evidence to guide pregnancy care.
We are also aiming to make sure this tool becomes part of routine clinical practice, so women receive personalised, easy-to-understand information that helps them make informed decisions about pregnancy. Ultimately, we want every woman with CKD to have access to evidence-based advice that reflects individual circumstances."Dr Kate Bramham.
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