Trajectories of maternal depressive and anxiety symptoms from pregnancy to five years postpartum and their prenatal predictors

Depression and anxiety disorders are highly prevalent among childbearing women, with rates as high as 30% [1, 2]. Maternal depression and anxiety are associated with poor health outcomes for the woman and her entire family [3, 4], which may have serious implications for the child’s developmental and psychological outcomes if untreated [5, 6]. Moreover, chronic depression affects long-term maternal health, with increased psychiatric morbidity (most notably more frequent and severe depressions) as well as physical and cognitive decline [7].

There is a growing evidence that maternal depressive and anxiety symptoms are heterogeneous, highly diversified with their onset, course, duration, and severity [8‐12]. Nandi et al., reviewed population-based studies of depression and anxiety trajectories and concluded that research in this area is still in its infancy; nonetheless, they found studies which confirm distinct groups of symptom trajectories for depression and anxiety (i.e., clusters of women who follow similar symptom patterns s over time), and that these trajectories are associated with risk factors that may vary between groups [9]. A more recent systematic review of perinatal depressive symptom trajectories found a similar pattern of depressive trajectories across studies and emphasized the need for further research within different settings [13].

Different methods have been used to model the developmental trajectories of maternal mental health symptoms over time. Both longitudinal mixed-effects and latent growth curve models model individual variabilities of these symptoms over time using a single growth curve, assuming that all individuals belong to the same underlying population [13]. Hence, these models may oversimplify the underlying complexity and heterogeneity of symptoms [13]. Alternatively, group-based trajectory modeling can be used to identify clusters of individuals who follow a similar evolution of behaviour [14]. This method is particularly important in the case of maternal depression and anxiety, as it allows for capturing the diversity of these symptoms in terms of onset, course, timing, and severity [15]. Furthermore, these models do not require prior information on the number and shape of groups, and they allow the magnitude and direction of change of depressive or anxiety symptoms to vary between different trajectories [14].

Previous research on the trajectories of maternal depression has examined the period between late pregnancy up to 1 to 2 years postpartum [16‐18]. Very few studies have examined maternal anxiety trajectories with most up to 1–2 years postpartum, with mixed results [16, 17, 19]. These studies provide evidence for longitudinal trajectories of maternal depression and anxiety; but, findings vary with the study population, location, and start and length of follow-up. Moreover, whereas the predictors for maternal depression and anxiety are well documented, there remains a paucity of research that links longitudinal trajectories of maternal depression and anxiety to their risk factors. This is particularly important as some risk factors may be associated with certain subgroups of women with maternal depression or anxiety, which would allow for targeted interventions. Early intervention directed towards at high risk women has been shown to reduce the risk of developing major depression [20]. Thus, it is essential to explore the trajectories of maternal depressive and anxiety symptoms beyond the perinatal period not only to recognize which women target by early mental health interventions but also to identify modifiable risk factors.

This study sought to identify maternal depressive and anxiety symptoms’ trajectory groups and their antenatal predictors and answer the following questions: 1. What are the distinct trajectory patterns for maternal depressive symptoms from pregnancy to 5 years postpartum, and what are the antenatal predictors associated with these trajectory groups? and 2. What are the distinct trajectory patterns for maternal anxiety symptoms from pregnancy to 5 years postpartum, and what are the antenatal predictors associated with these trajectory groups?

Over 50% of participants were primiparous, and most were Caucasian women living in a stable relationship with a moderately high socioeconomic status (see Table 1).

We identified four trajectory groups of maternal depression and three trajectory groups of maternal anxiety. The four depression trajectory groups were: low-stable (35.0%), moderate-stable (54.0%), moderate-increasing (5.2%), and high-decreasing (5.9%). Women who belonged to the low-stable and moderate-stable had EPDS scores that were below the cutoff point of clinical significance throughout the period of follow-up. Our findings are consistent with other studies, such as van der Waerden et al. [10], Denckla et al. [11], Campbell et al. [35] and Luoma et al. [33], which identified trajectory groups with no symptoms, low symptoms, and/or moderate symptoms of depression that were relatively stable across the period of follow-up and had the highest proportion of participants.

Like our high-decreasing group, van der Waerden and colleagues identified a prenatal group (5%) with high symptoms during pregnancy that decreased after giving birth and increased again between 36 and 60 months postpartum [10]. The slight increase in EPDS scores seen between the 36th and 60th months postpartum could possibly be related to a subsequent pregnancy, although this information was not readily available from the FIP data. Whereas previous studies concluded a small group of high symptoms that were relatively stable over time (also referred to as “chronic”) [10, 11, 33, 35], groups with high depressive symptoms in the present study displayed more fluctuation over time. Nonetheless, caution is required when comparing our results to these studies because of the variation in the period of follow-up and the tool used to assess depression.

We also identified three anxiety trajectory groups, very low-stable (13.0%), low-stable (58.1%), and moderate-stable (29.0%). Bayrampour et al. [16], documented five trajectory groups of maternal anxiety among 1445 women in Canada, who were followed from pregnancy to 1 year postpartum. Around 70% of the women in our sample experienced very low or low anxiety symptoms throughout the period of follow-up, which is comparable to Bayrampour’s results [16]. Almost a third of our sample had moderate-high anxiety symptoms that were stable across pregnancy to 5 years postpartum, whereas Bayrampour et al., concluded two groups of high anxiety symptoms that varied over time; antepartum and postpartum groups. They also concluded a very small group (1.5%) with chronic anxiety symptoms [16]. Likewise, the three trajectories (decreasing, increasing, and transient groups) with moderate-high anxiety symptoms in Barthel’s study showed fluctuation across the perinatal period [19].

We identified maternal risk factors associated with maternal depression and/or anxiety trajectory groups; high stress level and history of depression consistently predicted groups with moderate to high depressive or anxiety symptoms, and as the severity of symptom increases the magnitude of the impact of these factors increase, suggesting a dose-response relationship. As Britton [2] documented, women who have experienced depression in the past are vulnerable to both depression and anxiety during pregnancy, postpartum, as well as to persistent symptoms that extend well beyond the perinatal period. The present study concludes that stress is a major determinant of women’s mental health, especially during childbearing period, which is also consistent with van der Waerden and Bayrampour’s results [10, 16]. Researchers report that stress can invoke hormonal changes including increased activity of the HPA axis, and reduced levels of norepinephrine [36, 37], which can trigger maternal depressive and/or anxiety symptoms. Being non-Caucasian emerged as a significant predictor of trajectory groups with high depressive symptoms, which is consistent with van der Waerden et al.’s [10], conclusions. Low income has been documented to increase the risk of both depression and anxiety [2, 38], as it was for the trajectory group with moderate anxiety symptoms but, this factor was not significantly associated with distinct trajectory groups for depressive symptoms. This could be related to the small sample size of groups with high depressive symptoms, and the small number of low-income participants in our sample. The only behavioural factor that significantly predicted high depressive symptoms groups was tobacco use, which is in keeping with the literature that showed a significant association between prenatal smoking and perinatal depression [39‐41].

Strengths of the present study are the longitudinal nature and the repeated assessments during pregnancy, postpartum and up to 5 years postpartum and the use of validated screening tools for maternal depression and anxiety. Our sample included women who may be at low risk of maternal mental disorders (mostly Caucasian women with relatively high socioeconomic status), and thus the generalizability of our results may be limited to women of similar circumstance. The high attrition rates, particularly of those who could be at high risk of being depressed or anxious (such as non-Caucasian women, women with low socioeconomic status), which may have led to the underestimation of the severity of these disorders, and may have affected the significance and magnitude of association with maternal risk factors. We considered baseline covariates in our analysis, as information about some time varying covariates (stress, income, etc.) was not collected at each assessment wave. The size of some trajectory groups was small, which may have affected the power to detect true associations and their precision in relation to some of the risk factors.

Our results have shown that while some women with perinatal mental health symptoms may recover quickly, for others, these symptoms may be chronic. This heterogeneity of symptoms may necessitate multiple assessments for depressive and anxiety during pregnancy and the postpartum period, and beyond to recognize women at high risk of ongoing depression or anxiety. Furthermore, recognizing these women may allow for preventative and treatment interventions, which may alter symptom progress over time. Healthcare providers for women in the perinatal period should inquire about past psychiatric illness, as it appears to be a major predictor of perinatal depression and anxiety [2, 38, 42], and about stress levels, particularly during pregnancy and around birth, which can be major transitional periods in a woman’s life. Public health interventions that target some of the modifiable risk factors (e.g. smoking) specifically designed for women in the perinatal period may reduce the burden of these illnesses at the population level. Further research is recommended to examine the evolution of depressive and anxiety symptoms over longer periods and among different populations, particularly high-risk populations of women.