Is gestational diabetes associated with adverse maternal and child mental health outcomes?

Gestational diabetes mellitus (GDM) is diabetes (i.e. sugar levels being too high in the blood) arising during pregnancy. Around one in 20 pregnant women are affected in the UK. Mental illness during pregnancy is even more prevalent and is the most common illness to affect women during the perinatal period (during pregnancy or one year following delivery), with around one in five affected in the UK. While it is known that depression is twice as common in the general population amongst those who have diabetes, as those who do not, less is known about the link between mental illness and GDM, including how common mental illness is in those with GDM. Even less is known about potential reasons for a relationship between GDM and mental illness in the perinatal period. Both GDM and perinatal mental illness have been linked to possible emotional problems and learning delays in the child. However the effect of having both mental illness and GDM on the child has never been studied. Yet both GDM and mental illnesses are preventable conditions.

During the proposed fellowship I will:
1) Investigate the extent to which GDM increases the risk of perinatal mental illness.
2) Investigate whether or not mothers with GDM who also have mental illness during pregnancy are more likely to go on to develop diabetes in the future.
3) Compare the development of children whose mothers had GDM and mental illness during pregnancy to those whose mothers had GDM but no mental illness.
If links are found, reasons for these will be explored.

In my first study, I will systematically review the existing relevant research literature, assessing its quality, to inform my own research methods. During this review, I will aim to calculate how common mental illnesses are during pregnancy and in the year following delivery for women with GDM in order to ascertain the extent of the risk for mental illness in women have GDM. I will also explore potential reasons why this might be.

In my second study, I will use information collected from a group of mothers and their children in Bradford (called the Born in Bradford: BiB study) to answer each of my research questions. All mothers in the study were offered a test for GDM. This will provide information on which mothers had GDM (681 cases of GDM from 9779 women in total) then I can examine to what extent these women are more likely to have mental illnesses than women without GDM.

Diagnoses of diabetes up to the present day in mothers following their diagnosis of GDM will also be available from primary care records. This will mean I can examine whether women with GDM and mental illness are more likely to develop diabetes after birth compared with women with GDM and no illness.

I will then use two assessments completed by the child's teacher to examine the effects of GDM and mental illness in the mother on the child. One is of their emotional development (from a standard questionnaire) at the age of four years and the other is of their performance at school from national assessments at the age of seven years. In exploring potential reasons for significant links that I find, I will use information from the study about the mother's lifestyle such as diet and physical activity levels and blood tests from the newborn and mother.

This research will provide knowledge and a better understanding of the link between GDM and mental illness. If it appears that mental illness in those with GDM influences the development of diabetes in the future and the development of the child then this research should help scientists to develop strategies for improving the long-term health of not only the mother but also her child.

Background:gestational diabetes (GDM) is glucose intolerance with onset during pregnancy. It has a UK prevalence of between five and 10% and leads to adverse outcomes for mother and baby, including increased risk of type two diabetes (T2DM) in the mother and adverse child neuro-behavioural outcomes. Mental disorder is the most common morbidity of the perinatal period and is also associated with adverse child neuro-behavioural outcomes. There has been no research on how mental disorder influences future outcomes in mother and child in those with GDM.
Objectives:to establish the extent to which GDM is associated with adverse maternal mental health outcomes and whether mental disorder in those with GDM is associated with subsequent development of T2DM and adverse child neuro-behavioural outcomes.
Methods:Study 1a- systematic review and meta-analysis of prevalence and odds of all perinatal mental disorders in women with GDM.
Studies 1b, 2 and 3 utilise the Born in Bradford cohort.
Study 1b-risk for perinatal mental disorder in women with GDM will be assessed from a questionnaire about mental symptoms and diagnoses from primary care records. Mechanisms for the association will be explored including inflammation and behavioural factors.
Study 2-future risk of T2DM in women with GDM and antenatal mental disorder will be investigated using primary care diagnoses of T2DM. Behavioural factors such as diet and physical activity will be explored as potential mechanisms.
Study 3-neuro-behavioural outcomes of children whose mothers had GDM and antenatal mental disorder will be investigated using two measures of the child's development at ages four and seven. Maternal glycaemic control and persistence of mental disorder into the postnatal period will be explored as potential mechanisms.
Potential benefit and impact:exploring the relationships between GDM and mental disorder and potential mechanisms for the associations will help inform tailoring of healthcare interventions

Who might benefit?
*Government and global policy makers
*The public
*Patients
*The wider research community (see academic beneficiaries section)

How might they benefit?
Greater understanding of the relationship between gestational diabetes (GDM) and mental disorder has widespread implications for the public, pregnant women, patients with GDM and the children of those affected by GDM. It should also help to inform public health policy in the UK and further afield.

Government and global policy makers
In their National Framework for Diabetes1, the Department of Health in England states as one of their standards that those with GDM receive care that promotes their psychological well-being and optimises the health of their baby. A greater knowledge of the mental health impact of GDM, the resulting effects on the child and subsequent risk of the mother developing type two diabetes could help to support this aim. Further key policy messages which may emerge from this research relate to the importance of early identification of and possible screening for mental disorder in those with GDM.
Globally, the burden of non-communicable diseases (NCDs) such as obesity and diabetes is growing. Mirroring the upward trends in the prevalence of NCDs is a rising apparent prevalence of GDM, due possibly in part to growing numbers of obese mothers2. As such, NCDs are finally being prioritised on the global health agenda and further knowledge of the longer term effects of and interaction of physical and mental health in those with GDM could help inform evidence-based global policy making.

The public
With regards maternal and fetal wellbeing, there is much emphasis on optimising physical health of the mother during pregnancy. By adding new evidence to what is known about the links between physical and mental health, this research will highlight the importance of mental wellbeing in pregnancy, in addition to physical wellbeing. This in turn may reduce some of the stigma associated with mental illness in the perinatal period and inform anti-stigma campaigns. Reducing stigma ultimately may encourage more women experiencing mental illness during pregnancy to seek help. The perinatal period is increasingly being viewed as a window of opportunity to intervene early to halt possible adverse developmental trajectories being established in the child. Given the links between perinatal mental illness and future emotional and behavioural problems in the child, it is important to ensure that mothers are mentally and physically healthy not only for themselves but also for their children. Understanding some of the effects on the child of in utero exposures such as those explored within this research can help inform interventions aimed at reducing exposure to them.

Patients
If evidence from the project supports a relationship between GDM and mental disorder and in turn an influence on longer-term risks, this adds support for early recognition and treatment of mental disorder in the GDM population. Thus women with GDM could benefit from the research through increased awareness of the challenges that they face when they are diagnosed and increased provision of psychological support, leading to improvements in their quality of life.

1)Department of Health.National Service Framework for Diabetes.Available from: https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/198836/National_Service_Framework_for_Diabetes.pdf.2)The global challenge of diabetes.Lancet 2008;371:1723.