Hypertensive Disorders of Pregnancy - the Neonatal Burden of Disease

Around one in ten women have high blood pressure in pregnancy. This is potentially serious, with risks to the woman and her baby. Whilst maternal deaths from high blood pressure in pregnancy are now rare in the UK, blood pressure problems in pregnancy still cause many stillbirths and early births. Studies have shown that women of Black and Asian backgrounds are more likely to have worse pregnancy outcomes when blood pressure problems in pregnancy develop.

This study aims to:

i) describe the burden of disease of high blood pressure in pregnancy amongst babies admitted to neonatal units on a national scale.

ii) investigate outcomes for babies born to women with high blood pressure in pregnancy admitted to UK neonatal units across maternal ethnic groups.

To complete this study, we will use the National Neonatal Research Database, which holds population-level data for all babies admitted to neonatal units (where unwell babies receive care) in the UK. We will look at records of babies admitted to neonatal units in England and Wales between 2012 and 2020. The records will include information on over half a million babies and their mothers. We will assess how many babies admitted to neonatal units were born to women who had high blood pressure in pregnancy. We will report the outcomes of these babies, and how they compare to babies born to women without high blood pressure in pregnancy. We will analyse whether outcomes for babies born to women with high blood pressure in pregnancy varies according to maternal ethnicity, and investigate what may be driving differences we find.

Study Aims

This study aims to:

* quantify the proportion of all babies admitted to neonatal units born to women with a hypertensive disorder of pregnancy
* describe the national neonatal morbidity, mortality and resource use of babies admitted to neonatal units born to women with a hypertensive disorder of pregnancy
* examine ethnic disparities in neonatal outcomes of babies admitted to neonatal units born to women with hypertensive disorders of pregnancy.

The National Neonatal Research Database (NNRD)

The NNRD is an approved research database constituting real-world prospective clinical data extracted from point-of-care neonatal electronic health records with complete coverage of infants admitted for neonatal care to National Health Service (NHS) neonatal units in England and Wales (since 2012) and Scotland (since 2015). A defined data extract of approximately 450 items (the Neonatal Data Set) is transmitted quarterly to the Neonatal Data Analysis Unit at Imperial College London for data linkage and cleaning prior to entry into the NNRD. To date, the NNRD contains data for over a million babies (approximately 80,000 babies annually). High completeness and accuracy (\>95%) of neonatal data held in the NNRD has been confirmed by formal comparison with a multicentre, randomised placebo-controlled trial.

Study Design

This study is a secondary analysis of an existing national electronic health record population cohort using anonymised, routinely recorded clinical data from the National Neonatal Research Database (NNRD). There will be no new patients recruited and there will be no changes made to patient care.

The research team will work with NNRD data analysts to extract anonymised data from the NNRD. A cohort of babies born to women with a hypertensive disorder of pregnancy (HDP) will be defined based on records of maternal medical problems prior to pregnancy, obstetrics problems during pregnancy, medications given during labour and neonatal discharge diagnoses. The morbidity, mortality and health resource use of this cohort will be described in depth. This cohort will also be compared to a cohort of babies born to women without a hypertensive disorder of pregnancy. The HDP cohort will also be stratified by maternal ethnicity to investigate disparities in outcomes.

Eligibility Criteria:
Inclusion Criteria:

* Must be born between 1st January 2012 and 31st December 2020
* Must be admitted to and received all care in a National Health Service (NHS) neonatal unit in England or Wales

Exclusion Criteria:

* None