Lifestyle, Obesity, Diabetes: Optimising IVF Outcomes for Patients

The latest PET (Progress Educational Trust) event explored how lifestyle factors – particularly obesity and diabetes – can impact upon IVF outcomes, fertility, and the chances of a health pregnancy.

The event – 'Lifestyle, Obesity, Diabetes: Optimising IVF Outcomes for Patients' – was held in Edinburgh in partnership with the Scottish Government, and brought together four experts from distinct specialist areas to offer a multidisciplinary perspective on the issues.

Sarah Norcross, director of PET, provided a brief overview of the eligibility criteria for accessing IVF treatment before introducing the first speaker Dr Anthony Nicoll. Dr Nicoll is senior medical officer for maternal and women's health for the Scottish Government, as well as a consultant obstetrician and gynaecologist at Ninewells Hospital, Glasgow.

Dr Nicoll opened the discussion by outlining the prevalence of obesity and diabetes in Scotland, and the significant risks that these conditions pose to maternal health. He noted that 25 percent of women in Scotland have a body mass index (BMI) over 30, rising to 32 percent in the most deprived areas. Because eligibility for IVF in Scotland requires the prospective birth mother to have a BMI below 30, this suggests that many women are currently unable to access NHS-funded fertility treatment. He went on to explain the risks associated with obesity and diabetes during pregnancy, noting the possibility of cardiovascular complications and gestational diabetes in women with obesity, as well as hypoglycaemia and increased infection in those with diabetes.

Having outlined the maternal risks, Dr Nicoll went on to explain the complications that can arise during each stage of obstetric care, emphasising their potential impact on both the pregnant woman and the prospective child. For the woman, this includes an increased risk of pregnancy loss, as obesity and diabetes are associated with 1.5- and 2.5-fold increase in spontaneous miscarriage respectively. For the prospective child, risks include a higher likelihood of congenital abnormalities, which can often be challenging for clinicians to identify.

Having shared sobering statistics regarding maternal and obstetric risks, Dr Nicoll concluded by discussing ways that maternity services can reduce these risks, including the role of early intervention by professionals. In an ideal scenario, this includes speaking to patients before they even become pregnant.

This last point was picked up by the next speaker, Rebecca Reynolds, who is professor of metabolic medicine at the University of Edinburgh's Centre for Cardiovascular Science and founder of the Lothian Metabolic Antenatal Clinic. She began by exploring the question of whether the pre-pregnancy period is an appropriate time to help women lose weight, noting that while various national and international professional bodies recommend that patients begin pregnancy at a healthy weight, they rarely specify when and how weight loss should take place. She also highlighted the challenge of getting women to enrol in, and then follow, recommended weight loss programmes.

Professor Reynolds went on to consider the latest issue in weight loss and pregnancy, so-callled Ozempic babies. This term gained prominence on social media after some women who had previously struggled with fertility issues reported unexpectedly becoming pregnant while using weight loss drugs. Professor Reynolds expressed some concern about the growing popularity of GLP-1 receptor agonist drugs for weight loss, and the fact that these are sometimes used during pregnancy – despite current clinical guidance advising women to stop taking such medications at least two months before becoming pregnant. She emphasised the uncertainty and lack of robust clinical evidence concerning the possible effects – on both mother and child – of using weight loss medication before and/or during pregnancy.

To conclude, Professor Reynolds raised the question of when intervention is most effective for women struggling with diabetes, obesity, and weight management. Although preconception intervention could be beneficial, she noted various difficulties associated with this, including the challenge of identifying those who might benefit from help. She said there was a stronger case for postpartum intervention, where lifestyle changes could help to avert intergenerational obesity. At the same time, she highlighted the UK Preconception Partnership, which works with policymakers to support preparation for pregnancy and parenthood.

The third speaker was Colin Duncan, professor of reproductive medicine and science at the University of Edinburgh's Centre for Reproductive Health, and a subspecialist in reproductive medicine and surgery at the Edinburgh Fertility Centre.

Professor Duncan began by arguing that obesity is not so much a lifestyle choice as it is a chronic, relapsing health condition. This was reflected in some of the research he cited, which set out the challenges of achieving sustained weight loss – whether via lifestyle changes, medication or even gastric bypass surgery – due to a phenomenon that he called the 'memory of obesity'. He pointed out that women with obesity struggle to access NHS-funded fertility treatment because of the eligibility restrictions based on BMI, while at the same time clinical support for weight management is often lacking, leaving patients without effective help.

He then explained that while obesity can affect IVF by potentially prolonging treatment or increasing medication requirements, it does not appear to reduce pregnancy rates. He contrasted the variable of the woman's BMI with the variable of the woman's age, arguing that IVF entails greater risks for a woman with a healthy weight who is older than 40 than it does for a young woman who is obese.

Professor Duncan concluded by referencing multiple studies evaluating pre-IVF weight loss interventions (see here, here and here). These studies suggest that there is little compelling evidence that lifestyle interventions for weight loss improve birth outcomes. In light of this, Professor Duncan asserted that IVF treatment should be offered earlier to patients who are obese, in order to reduce the impact of age.

Finally, Niamh Shortt, professor of health geographies at the University of Edinburgh and co-director of the Centre for Environment, Society and Health, offered a different perspective. She focused on the social and structural determinants of health, emphasised the role of social factors in pregnancy and birth outcomes, and explained how socioeconomic contexts can shape health behaviours which are linked to obesity.

Professor Shortt used smoking as an example to illustrate the impact of social determinants on health, noting that while smoking during pregnancy has decreased overall, it has not declined equally among socioeconomic groups. Across Scotland, one in seven adults smoke, but the proportion differs widely depending on the neighbourhood. This suggests that poorer lifestyle habits are framed by sociopolitical contexts and local behavioural norms.

Scotland aims to have a tobacco-free generation by 2034, but Professor Shortt said that this was unlikely to be achieved in all geographical areas. She referred to a study of women's smoking behaviours, to illustrate that the stigmatisation of smokers can cause pregnant women and mothers to disengage with the health service, as they feel pressured to conceal their behaviours.

To conclude, Professor Shortt emphasised the importance of amplifying women's voices when trying to encourage lifestyle changes. She noted that lifestyle choices are context-dependent, and argued that lifestyle interventions must be co-designed with women.

The event concluded with audience questions and comments. Some attendees asked whether lifestyle choices by male partners (such as poor diet and alcohol consumption) can affect impact IVF outcomes, and asked whether weight loss drugs should be used by prospective fathers. Professor Duncan confirmed that male obesity can affect fertility, and noted that there is currently a lack absence of evidence regarding whether weight loss injections affect male fertility (either positively or negatively). He argued that this was an area that deserved further research.

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PET is grateful to the Scottish Government for supporting this event.

Register for these upcoming PET events:

• Robert Edwards at 100: Remembering an IVF Visionary, taking place online on Wednesday 24 September 2025 – register here.
• Mitochondrial Donation: Does It Work? What Next?, taking place online on Wednesday 8 October 2025 – register here.
• Rare Disease Genomic Testing: How Do We Make Access Equitable and Timely?, taking place online on Wednesday 22 October 2025 – register here.
• What Does Genomics Mean for Fertility Treatment?, the PET Annual Conference, taking place in person in London on Wednesday 10 December 2025 – register here.