According to World Health Organisation, 15 million premature or preterm deliveries (PTD) ( giving birth before the 37th week of pregnancy) are reported annually and increasing globally. The premature delivery rate is estimated to range from 5% to 18% in 184 countries. In the UK, the PTD rate has remained stable since 2010 ranging between 7% to 8% of live births. Pregnancy complications are associated with poor health in the mother and the baby. From a long-term perspective, compared to women who delivered at term, previous studies have consistently suggested that women with a history of premature delivery are at increased risk of subsequent chronic diseases including heart disease. High blood pressure and diabetes are established risk factors for heart and blood vessel diseases. Nevertheless, less attention has been focused on the relationship between premature delivery and subsequent risk of hypertension and type 2 diabetes in the mother.
The study aims to find an association between premature delivery, high blood pressure, and type 2 diabetes using routinely collected UK primary care data (CPRD).
The potential importance of the findings lies in enabling mothers who have given PTD to be aware of the increased risk of high blood pressure and type 2 diabetes. Mothers with a history of PTD may be potential targets for strategies for prevention of hypertension or type 2 diabetes mellitus. Furthermore, the potential risk of heart diseases can be managed.
• Study population of interest
Adult women aged 18 years to 49-years at baseline will be considered the study population.
• Primary exposure and outcomes,
Women with a diagnostic code for preterm delivery (PTD) (gestational age over 20 weeks and under 37 weeks) will be included as the exposed group.
The outcomes will be the incident diagnosis of hypertension or type 2 diabetes mellitus(T2DM) captured using primary care diagnostic codes (Read codes). Patients with a record of any hypertension at baseline will be excluded in the analysis for hypertension outcome. Patients with a record of T1DM or T2DM at baseline will be excluded in the analysis for T2DM outcome.
• Data sources that will be used to achieve the aim and objectives
A primary care dataset (Clinical Practise Research Datalink), which is a large database of longitudinal medical records from primary care, will be used for hypothesis testing.
• Study design, methods including the main statistical tests
This is a retrospective matched population-based cohort study. In hypertension and T2DM outcomes cohort study, Cox proportional hazard regression techniques will be used to estimate the crude and adjusted hazard ratios (aHRs) and their corresponding 95% CIs of hypertension or type 2 diabetes mellitus in women with history of preterm delivery compared to those who delivered at term. The proportionality of hazards assumption will be checked by comparing log-log plots of survival and the Schoenfeld test.
• Intended public health benefit
If a higher risk of these outcomes is observed, this may help to elucidate the association between PTD and hypertension or T2DM, which would further benefit efforts to identify the eligible women who might benefit from regular cardiometabolic health checks.
Incident diagnosis of hypertension.
Incident diagnosis of Type 2 diabetes mellitus.
Nicola Adderley - Chief Investigator - University of Birmingham
Ami Song - Corresponding Applicant - University of Birmingham
Anuradhaa Subramanian - Collaborator - University of Birmingham
Kelvin Okoth - Collaborator - University of Birmingham
Krishna Gokhale - Collaborator - University of Birmingham
Krishnarajah Nirantharakumar - Collaborator - University of Birmingham
CPRD GOLD Pregnancy Register