This project took place at our London centre which operated between 1995 and 2021.
Why do we need this research?
In the UK, 1 in 5 pregnant women are obese (they have a BMI over 30). Being obese during pregnancy can increase the risk of complications such as pre-eclampsia, gestational diabetes, stillbirth or premature birth. Obese women are also more likely to have babies that are too large at birth, which can lead to problems during labour, and their babies are at higher risk of developing diabetes and heart problems later in life.
In the UPBEAT study, which included over 1,500 obese pregnant women, researchers funded by Tommy’s found that a programme of diet and exercise advice did not reduce the number of women who developed gestational diabetes or had large babies, although there were other signs that it did make women healthier. However, the chance of a woman experiencing pregnancy complications is higher when obesity is more severe, and so our researchers wanted to find out whether the programme would be more effective in women with the most severe obesity.
What happened in this project?
To do this, our researchers split the women from the UPBEAT study into three groups according to their BMI (30–35, 35–40 and over 40). They found that the programme of diet and exercise advice led to a bigger reduction in the amount of weight gained during pregnancy – compared with standard antenatal treatment – for the most obese women (BMI over 40) than for the women whose obesity was less severe. Despite this, the programme did not reduce the numbers of women who developed gestational diabetes or who had large babies, even in the group with the highest BMI.
What difference will this project make?
In this project, a programme of diet and exercise advice was shown to be more effective amongst women with the most severe obesity. This means that, moving forward, it is important that researchers who are looking at ways of improving pregnancy outcomes for obese women do not consider these women to be one uniform group, but instead split these women into different groups, according to their BMI.