Infertility treatment and postpartum mental illness: a population-based cohort study

Abstract

Background: Subfertility and infertility treatment can be stressful experiences, but it is unknown whether each predisposes to postpartum mental illness. We sought to evaluate associations between subfertility or infertility treatment and postpartum mental illness.

Methods: We conducted a population-based cohort study of individuals without pre-existing mental illness who gave birth in Ontario, Canada, from 2006 to 2014, stratified by fertility exposure: subfertility without infertility treatment; noninvasive infertility treatment (intrauterine insemination); invasive infertility treatment (in vitro fertilization); and no reproductive assistance. The primary outcome was mental illness occurring 365 days or sooner after birth (defined as ≥ 2 outpatient visits, an emergency department visit or a hospital admission with a mood, anxiety, psychotic, or substance use disorder, self-harm event or other mental illness). We used multivariable Poisson regression with robust error variance to assess associations between fertility exposure and postpartum mental illness.

Results: The study cohort comprised 786 064 births (mean age 30.42 yr, standard deviation 5.30 yr), including 78 283 with subfertility without treatment, 9178 with noninvasive infertility treatment, 9633 with invasive infertility treatment and 688 970 without reproductive assistance. Postpartum mental illness occurred in 60.8 per 1000 births among individuals without reproductive assistance. Relative to individuals without reproductive assistance, those with subfertility had a higher adjusted relative risk of postpartum mental illness (1.14, 95% confidence interval 1.10-1.17), which was similar in noninvasive and invasive infertility treatment groups.

Interpretation: Subfertility or infertility treatment conferred a slightly higher risk of postpartum mental illness compared with no reproductive assistance. Further research should elucidate whether the stress of infertility, its treatment or physician selection contributes to this association.

Figure 1:

Study flow chart. Note: OHIP = Ontario Health Insurance Plan.

Figure 2:

Risk of a maternal mental illness outcome within 1 year after birth in relation to type of pregnancy conception. Relative risks (RRs) are adjusted for maternal age, income quintile, rurality, immigrant status, parity, chronic hypertension, diabetes mellitus and obesity. Note: CI = confidence interval, Composite outcome = mental health outcome of any severe mental health or outpatient mental health encounter, IT = infertility treatment, Ref. = reference category.

Figure 3:

Risk of the composite maternal mental health outcome of any severe mental illness or outpatient mental health encounter within 1 year after birth, in relation to type of pregnancy conception, further stratified by patient and pregnancy characteristics. Relative risks (RRs) are adjusted for maternal age, income quintile, rurality, immigrant status, parity, chronic hypertension, diabetes mellitus and obesity. Eligibility for the Ontario Drug Benefit (ODB) was based on an individual having ≥ 1 ODB-insured medication claim between the estimated date of conception and 1 year after the index birth. Note: CI = confidence interval, IT = infertility treatment, Ref. = reference category, SMM = severe maternal morbidity.