Lifetime prevalence of depression during the peripartum period
Just over 97% of AGDS participants (n = 20,191) reported previous diagnosis of depression by a health professional, of whom 88% met DSM-V criteria for MDD. Of these participants with major depression, 75% (n = 15,198) were female with median age of 39. Among female participants, 7,182 (47%) reported having given birth, and, of these, 5,058 (70%) met criteria for PND.
Of the 7,182 parous women, 2,933 reported a history of major depression prior to first pregnancy. At least one episode of PND (priorDep_PND) was reported by 2,261 (77%) of these 2,933 women, whilst the remaining 672 women with no PND episodes (23%) formed their comparison group (priorDep_noPND). A total of 878 women reported that their first episode of depression occurred during pregnancy or within the first 6 months after delivery (PNDfirst), whilst all women who met criteria for major depression, had given birth to at least one child but did not satisfy criteria for PND (Dep_noPND, n = 2124) formed its comparison group. Fig. 1 and Supplementary Table S1 provide details of the sample selection process. Table 1 shows the reported time of onset of symptoms for both case groups (only during pregnancy, only after delivery, or both before and after delivery).
Reported timing of symptoms of perinatal depression among women with PND. Results are shown for all those meeting PND criteria and separately for those with a prior history of major depression (priorDep) and those whose first onset of major depression was perinatal (PNDfirst).
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During pregnancy only
After delivery only
Both during pregnancy and after delivery
All PND cases (N = 5,058)
PriorDep (N = 2,261)
PNDfirst (N = 878)
The reported length of the worst episode of PND is shown in Fig. 2 for priorDep_PND and in Fig. 3 for PNDfirst. Full details are provided in Table S5. For both groups of cases, PND was most commonly reported to have lasted for more than six months. The most commonly reported time of onset for women whose episode began during pregnancy was during the first trimester, and for those whose episode began after delivery was within 0–4 weeks. PriorDep were more likely to report their worst episode to begin during pregnancy (33%), whereas PNDfirst overwhelmingly reported symptoms after delivery (80%). For both groups, symptom onset in the first trimester or 0–4 weeks postpartum was associated with longer duration of symptoms, significantly so for priorDep_PND (Table S5).
For both groups, more than 60% required some sort of professional help, although less than 45% of women reported using medication to deal with this worst episode (Fig. 4, Table S4).
Clinical and psychosocial risk factors for PND in parous women with a history of depression.
We investigated which risk factors are associated with PND in women with a previous history of depression. Figure 5 illustrates nominally significant results and all results are provided in Supplementary Table S6.
Among demographic variables, age at enrolment was significantly associated with PND. Each additional year of age at enrolment was associated with a 0.07 decrease in EPDS score. There was no association between marital status or level of education and PND. Ancestry (both non-European and Australian Indigenous) was significantly associated with PND (non-European: OR = 1.5, CI=[1.1–2.2], P = 2.0E-02; Australian Indigenous: OR = 2.3, CI=[1.2–5.1], P = 1.7E-02).
Five of thirteen psychiatric disorders (premenstrual dysphoric disorder (PMDD), attention deficit hyperactive disorder (ADHD), anxiety disorder, post-traumatic stress disorder (PTSD), and social anxiety disorder) were significantly associated with PND, although none survived Bonferroni correction. PriorDep_PND also reported more severe depression than PriorDep_noPND (Fig. 4).
There was a significant association between PND and a history of self-reported childhood emotional abuse (OR = 1.4, CI=[1.1–1.7], P = 2.0E-03) and neglect (OR = 1.3, CI = 1.1–1.6], P = 1.5E-02) and physical neglect (OR = 1.5, CI=[1.1-2.0], p = 1.2E-02), although only emotional abuse survived Bonferroni correction.
PND was significantly associated with the number of births, with the average number of live births being 2.1 for priorDep_PND compared to 1.9 for priorDep_noPND. There was no association between age at menarche and PND and no significant difference in the incidence of gestational diabetes, polycystic ovarian syndrome or endometriosis.
Although there was no significant difference in the incidence of NVP for all cases (P = 0.11), there was a significant difference in the severity of NVP between PriorDep_PND and PriorDep_NoPND. For PriorDep_PND, the odds that a woman with PND had experienced disruptive nausea during pregnancy, compared to PriorDep_NoPND, is 1.3 (CI=[1.1–1.6], P = 6.6E-03), significant after Bonferroni correction.
PriorDep_PND were significantly more likely to have tried more than three antidepressants than its comparison group (OR = 1.4, CI=[1.1–1.8], P = 1.4E-03), and were 1.5 times more likely (CI=[1.2–1.8], P = 4.6E-04) to report at least one side effect for antidepressants, compared with women with PriorDep_NoPND (including age and the number of antidepressants tried as covariates in the model) (Fig. 4). All of the 23 side effects were more commonly reported by PriorDep_PND, 16 of them significantly so, although only 4 survived Bonferroni correction.
Clinical and psychosocial risk factors associated with PND as first episode of depression.
As there may be unique risk factors associated with onset of depression perinatally, we conducted further analyses to evaluate differences between women who report their first episode occurring perinatally (PNDfirst) and those who did not experience PND. Similar to priorDep findings, we found that age at enrolment, age at first birth, number of births, and emotional trauma in childhood were associated with increased risk of PND (Fig. 4). PNDfirst also reported increased likelihood of trying at least 3 antidepressants, and experiencing 17 of the 23 side effects compared with controls, 4 of which were significant, although none survived Bonferroni correction. No associations were found with other variables. Full details of all results are provided in Supplementary Table S6.
Effect of time of onset on clinical and psychosocial risk factors associated with PND.
Symptoms of PND were experienced both during pregnancy and after delivery by 67% of priorDep_PND and 58% of PNDfirst. For these cases, the odds ratios of variables already significantly associated with these groups increased. For priorDep, association of PND with three comorbidities: ADHD, PTSD and social anxiety disorder remained significant after Bonferoni correction. Sexual abuse at any time became significantly associated with PND for priorDep as well as comorbidity with bipolar disorder, and PMDD became significantly associated with PNDfirst, although none of these survived Bonferroni correction. Full details are provided in Supplementary Table S7.