Self-Harm Risk in Pregnancy: A Recurrent Events Survival Analysis Using UK Primary Care Data

Aim: To determine if the risk of self-harm changes during pregnancy and the first post-partum year compared to other times in a woman’s life. Methods: Utilising the Clinical Practice Research Datalink, a primary care register, we followed women aged 15 to 45 years from the 1st January 1990 to 31st December 2017. Time was split into: pregnancy, 0-3, 3-6 and 6-12 months post-partum, and any other time outside the perinatal period. Additional time-varying covariates were constructed for: common mental illness (depression/anxiety); addiction (alcohol/drug misuse); serious mental illness (affective/non-affective psychosis); other mental illness (eating/personality disorders); age (15-45 in 5-year bands); and calendar year (1990-2017). UK region and index of multiple deprivation were also included. Utilising a gap-time and stratified Cox model to manage multiple self-harm events, we report unadjusted and adjusted HRs of self-harm associated with pregnancy and the post-partum compared to other periods. Pre-planned interactions examined whether or not effect measures were modified by mental illness exposure, age and birth outcome. Results: The analysis included 2,666,088 women, 1,102,040 pregnancies, 57,791, self-harm events and 14,712,319 person-years of follow-up. Compared to any other time, women were at lowest risk of self-harm during pregnancy (adjHR=0·53, 95%CI 0·49-0·58) and highest risk at 6-12 months post-partum (adjHR=1·08, 95%CI 1·02-1·15). Women with mental illness experienced the greatest self-harm risk reduction in pregnancy (adjHR=0·40, 95%CI 0·36-0·44) and at 6-12 months post-partum (adjHR=0·92, 95%CI 0·87-0·98). Post-partum younger women (15-19 adjHR=1·67, 95%CI 1·48-1·90; 20-24 adjHR=1·27, 95%CI 1·12-1·44) and women who experienced a pregnancy loss (adjHR=1.41, 95%CI 1·21-1·65) or termination (adjHR=1·93, 95%CI 1·72-2·17) were particularly at risk. Conclusion: Overall, pregnancy represents a time of reduced self-harm risk for women. This is  especially the case for women with a mental illness. Post-partum, young women represent a vulnerable group who may require additional support. Services aimed at planning for motherhood may have additional psychological benefit in self-harm reduction. Funded by the European Research Council (ref: GA682741) and the National Institute for Health Research (ref: 111905).The study sponsor and funder had no role in the study design, nor the collection, analysis or interpretation of data. Declaration of Interest: None to declare Ethical Approval: The authors assert that all procedures contributing to this work comply with the ethical standards of the relevant national and institutional committees on human experimentation and with the Helsinki Declaration of 1975, as revised in 2008. The study was approved by the Independent Scientific Advisory Committee (ISAC) for MHRA Database Research (protocol number: 17_187). All observational research using CPRD patient data with approval from ISAC was granted by a Health Research Authority (HRA) Research Ethics Committee (East Midlands—Derby, REC reference number 05/MRE04/87).