Incidence and prevalence of mental illness in pregnancy and the first five years after giving birth: a retrospective cohort study using electronic primary care data

Leads: Beck Taylor, Laura Quinn, Christine MacArthur (ARC). Ellie Jones, Jamie Rae Tanner (collaborators outside of ARC).

Dates: March 2021- March 2023

Background:

Mental health problems in pregnancy and the first year after birth affect up to 20% of women (National Collaborating Centre for Mental Health, 2018, Public Health England, 2019a) and cost the NHS around £1.2 billion per annual cohort of births (Bauer et al., 2014). Perinatal mental health (PMH) problems range from mild to severe (Royal College of Psychiatrists, 2018) with depression and anxiety being the most common (National Collaborating Centre for Mental Health, 2018).

Following an initial investment of £365 million to lay the foundations for perinatal mental health as part of the Five year Forward View for Mental Health (The Mental Health Taskforce, 2016), in England the NHS Long Term Plan (NHS England, 2019b) builds on this further to ensure that by 2023/24, at least 66,000 women with moderate to severe perinatal mental health problems will have access to specialist community care from pre-conception up to 24 months after birth in England.

Currently very little is known about the incidence and prevalence of mental health problems beyond 12 months postpartum (Goodman, 2004). It is not known whether the additional funding for more women with moderate/complex or severe PMH illness will meet the service need or whether the newly proposed two year postpartum ‘cut-off’ for access to PMH services is justified, or too long or too short.

Policy and Practice Partners:

Birmingham and Solihull Mental Health Foundation Trust. Partners are Specialist Perinatal Mental Health Psychiatrists, including the National Specialty Advisor for Perinatal Mental Health NHS England.

Aims and Objectives:

  • Describe the frequency, incidence rate and period prevalence of mental illness in pregnancy and each of the five years after giving birth (0-1, 1-2, 2-3, 3-4 and 4-5).
  • Determine whether there are any changes in incidence rates of maternal mental health problems in pregnancy and five years after giving birth between 1995-2020.
  • Determine factors associated with PMH illness treated and/or managed in primary care in pregnancy and first five years after giving birth.

Methods:

Design: Cross-sectional, retrospective cohort study and time series analysis

Setting: England, UK.

Participant population:

Data for this study will be obtained from the UK Clinical Practice Research Datalink (CPRD), a primary care database (GOLD) contains the computerised records form General Practices (GPs) in the UK covering approximately 8% of the UK population. Validation studies suggest high specificity and positive predictive value for detecting mental health problems in primary care data (John et al., 2016).

The population for the study is all women who have a third trimester, delivery code or postnatal medical record between 1995-2020 and registered at a GP that contributes to CPRD database. Women will be followed up for the five years following the birth of their baby to determine incidence of mental health problems during this period.

Measures:

The primary outcome is the incidence rate of mental illness in pregnancy and each of the first five years after giving birth. Secondary explanatory variables will explore maternal characteristics.

Analysis:

The following analyses will be conducted, subject to the coding and quality of variables within the CPRD data.Categorical variables will be presented as frequencies and continuous variables will be presented as mean and standard deviation or median and interquartile range. Statistical tests appropriate to the level of measurement will be used and 95% confidence intervals will be presented around estimates where relevant. Incidence rate (person-time rate) is defined as: the frequency with which a disease or other incident occurs over a specified time period and will be calculated as follows: (No of new cases/person years at risk (time each person was observed totalled for all persons)) multiplied by 1,000. Period prevalence is defined as the proportion of the population that has a mental health conditions during each specified time and will be calculated as follows: (number of women with mental illness during a given time period/population during that same time period) x1,000.

Main Results:

Project currently underway.

Conclusions:

Project currently underway.

Implications for Implementation:

Results will provide data as to the incidence and prevalence of mental health problems beyond 12 months postpartum to inform practice.

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