Abstract
This study examines the frequency of postpartum mental disorders in women who are primiparous and multiparous.
Postpartum mental disorders (PPMDs) are serious conditions ranging in prevalence, incidence, and severity. The disorders are mainly observed in women who are primiparous,1 and mothers with a history of PPMDs are understandably concerned about risk of recurrence after successive deliveries. In this study, we aimed to (1) examine the risk of a mental disorder in the postpartum period by parity and (2) provide an overview of the recurrence risk of PPMDs in affected women after subsequent deliveries.
Methods
We conducted a population-based cohort study using data from the Danish Medical Birth Registry,2 the Danish Psychiatric Central Research Register,3 the Danish National Prescription Registry,4 and the Danish Civil Registration System. We identified 414 673 women aged 15 to 45 years with a first live birth (or births) from January 1997 through December 2015 who had no recorded previous psychiatric disorders at the time of the delivery, as identified through the International Classification of Diseases, Eighth Revision codes 290 through 315 and Tenth Revision codes F00 through F99 or redeemed prescriptions for psychotropic medications (International Anatomical Therapeutic Chemical Classification codes N05 and N06).
The study was approved by the Danish Data Protection Agency. In Denmark, no informed consent is required for a register-based study that relies exclusively on deidentified data.
Postpartum mental disorders were defined within 6 months after the index delivery by inpatient or outpatient treatment for psychiatric disorders, excluding psychoactive substance misuse and mental retardation (primary diagnosis with any code from the entire F chapter of International Classification of Diseases, Tenth Revision codes, excluding codes F10 through F19 and F70 through F79) or redeemed prescription for psychotropic medications. The cumulative incidence of PPMDs for first, second, and third deliveries was estimated using the command stcompet in Stata version 15.0 (StataCorp), as previously described by Coviello and Boggess.5 This method accounts for competing risk from emigration and death. Data analysis took place from April 2019 to July 2019.
Results
Among women in the study population with no previous postpartum psychiatric history, the cumulative incidence of PPMDs was 1.0% (95% CI, 1.0%-1.1%) for first parity (4328 of 414 673). It was 1.6% (95% CI, 1.6%-1.7%) for second parity (4691 of 291 304) and 2.0% (95% CI, 1.9%-2.1%) for third parity (1584 of 80 230).
After the second delivery, the recurrence risk of a postpartum psychiatric episode for women who had PPMDs after their first delivery was 25.5% (95% CI, 23.8%-27.2%; 642 of 2536). After the third delivery, the recurrence risk was 56.8% (95% CI, 46.8%-65.6%; 60 of 106) for women who had PPMDs in the 2 previous postpartum periods (Figure).
Figure. Cumulative Incidence of Postpartum Mental Disorders After Liveborn Deliveries in Women With Histories of Postpartum Mental Disorders, 1997-2015.
PPMD indicates postpartum mental disorder.
Discussion
Interpretation of these results should consider the selection processes, study design, and definition of PPMDs. Women with PPMDs after first delivery may be less likely to have subsequent childbirths, and recurrence risks of PPMDS will consequently be influenced by the overall reproduction patterns in this group of women. We defined PPMDs through treatment records, including specialty care treatment and psychotropic drug prescriptions, and we consequently cannot generalize these results to women with milder, untreated cases of PPMDs or PPMDs treated with psychotherapy. The PPMD definition furthermore identified a group of women with severe PPMDs, which explains differences in overall incidences compared with other studies.6
These findings do not support the existing evidence that the risk of PPMDs is highest among women who are primiparous.1 If replicated, this result directly influences clinical practice in identifying women at risk for PPMDs and calls for discussions about selection and how overall reproduction rates can have influenced previous findings. Furthermore, we found that 1 in 4 women with PPMDs after first delivery will have a subsequent episode after the second delivery, and more than 1 in 2 women with PPMDs after both the first and second deliveries will have a subsequent episode after a third delivery. In conclusion, the recurrence risks of postpartum mental disorders are substantial and concerning. This information should be disseminated to clinicians and women with a history of these disorders, as well as considered in clinical practice for both prevention and treatment planning.
References
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