The present study identified four groups of maternal depressive symptoms trajectories, from late pregnancy to 6months after birth: "low depressive", "subclinical depressive", "moderate-low and increasing" and "persistent high depressive". The influence of severity and chronicity of maternal depressive symptoms on child development has been examined. We found that mothers experiencing persistent high symptoms are more likely to report that their children have a lower score on the ASQ-3 total, ASQ-se, and 3 ASQ-3 domains (fine, problem-solving, and personal-society motor). Similarly, children of mothers assigned to subclinical depressive symptoms were more likely to have lower scores in ASQ-3 total, 2 ASQ-3 domains (communication motor and gross motor), and ASQ-se, compared with children of low depressive symptoms. This study investigated the effect of maternal depression symptoms over time and found that "subclinical symptoms" and "persistent high symptoms” had an increased risk for poor emotional and behavioral development. As such, this study provides novel evidence of the negative impact of persistently high and subclinical depressive symptoms on delayed child development at eight months.
Some previous research supports our view. An association between maternal depressive symptoms at prenatal or postnatal, and child poor neurodevelopment was found [10, 11]. Kingston et al. explored the depression symptoms across four points from mid-pregnancy to one year postpartum and identified four distinct trajectories of maternal depressive symptoms: low level (64.7%), early postpartum (10.9%), subclinical (18.8%), and persistent high (5.6%). In multivariable models, the children born to women with persistent high depressive symptoms had the highest proportion of elevated behavior symptoms, followed by mothers with moderate symptoms (early postpartum and subclinical trajectories) and lowest for minimal symptoms[30]. Another study(N = 1983) also supporting mothers experiencing high anxiety symptoms in the perinatal period have an adverse impact on child developmental delays. They identified three distinct trajectories of maternal stress and anxiety symptoms from mid-pregnancy to 3 years postpartum. Multivariate analysis showed mothers belonging to the high anxiety symptoms class had an increased risk (adjusted OR 2.80, 95% CI 2.80 (1.42 ─ 5.51), p = 0.003) of having a child with developmental delays at 3 years[31]. But their explorations are limited to one aspect of child development, caused by maternal depression. As a result, they are unable to capture the simultaneous influence of maternal depression on multiple areas of child development, such as communication, motor, problem-solving and social-emotional development. It is important to note that, maternal with high depressive symptoms at prenatal had a significant effect on poor emotional and behavioral development compared with increased and persistent even at low-level symptoms. Researchers found that children of mothers who had elevated depressive symptoms during pregnancy had worse mental health in adolescence[32, 33]. The effect of prenatal maternal depressive symptoms on child outcomes is noteworthy. Further studies are warranted to explore how the course of prenatal and postnatal depression affects child development.
In the final multivariate model, we explored the relationships between maternal depression symptom trajectories and children's emotional and behavioral development after accounting for demographic, obstetrics, birth outcomes, and feeding factors. sleep quality at late pregnancy, low birth weight, breastfeeding at 3 month and lower education level of mothers were also associated with poorer emotional and behavioral for development children. Some of the characteristics might be pathways by which maternal mental health difficulties contribute to children’s emotional and behavioral difficulties. For instance, depression symptom might lead to chronic sleep loss and low birth weight. The former might contribute to adverse pregnancy outcomes and maternal and child stress ‘overload’, and the latter might increase the gross and fine motors risk of a diagnosis of neurodevelopment delay[34]. Depression symptom can also affect children by affecting mothers' behavior. Studies showed positive associations between breastfeeding and child neurodevelopment[35, 36].
Our findings have implications for physicians who provide care during pregnancy. Clinically, if we only considered women's scores using the recommended screening cut-off of 13 or greater on the EPDS, those assigned to the subclinical depressive symptom trajectory may not be identified as their mean scores are below the clinical cut-off points. However, the proportion of subclinical women is high, and the significant effect on the child neurodevelopment, this raises questions for current health care that rely on cut-offs to evaluate women's mental health requiring intervention or follow up, and provide evidence of early identification and support.
This study benefits from using longitudinal statistical modeling of data drawn from a prospective birth cohort study. However, there are several limitations to note. First, The EPDS test was self-written by the mother, which might lead self-report bias. Second, the EPDS was only assessed at late pregnancy for all women, not at first and second trimester, preventing classifying the trajectory of depressive symptoms during pregnancy by trimester. Third, we couldn’t include all covariates associated with children’s outcomes n the study. Finally, we supposed data were missing at random in the present analysis, this may result in an underestimate of maternal depressive symptoms as more depressed women may be more likely to miss a study assessment.