Introduction
Accumulating evidence has shown that prenatal and early life psychological stress and stress correlates, like maternal depression and anxiety, are linked to an increased risk of respiratory disorders including wheeze and asthma1 in the offspring. Psychological stress can affect the individual biology, progression, and management of respiratory disease throughout the lifespan2, 3. Maternal psychological functioning has been linked to the alteration of the immune system and lung development4 prenatally and in early childhood. Both prenatal and postnatal maternal psychological functioning is associated with higher risk of allergy, asthma, and wheezing development in infants5. The effects of prenatal and postnatal maternal stress have been examined independently from one another but the influence of the timing of exposure during critical periods of development has not been completely elucidated6-8.
A few recent studies have examined the impact of prenatal and postnatal maternal distress on childhood risk of atopic and respiratory disease9-11. Van der Leek et al11reported significant associations between maternal prenatal, recurrent postpartum, and late onset postpartum distress and higher risk of atopic dermatitis at age 5 years11. Prenatal maternal distress and late onset postnatal distress were also associated with asthma at 7 years of age11. Brew et al9 examined the association between maternal depression or anxiety during different exposure periods (pre-conception, pregnancy, postnatal, or current) and childhood asthma development. They did not identify a critical exposure period but rather reported that chronic exposure to maternal depression and anxiety is associated with offspring asthma. Ramratnam et al12 concluded that maternal stress and depression in the first 3 years were positively associated with respiratory illnesses and a moderate-wheeze-low-atopy-phenotype12.
Growing evidence has also demonstrated that critical windows of vulnerability may differ by sex of the offspring10. Our group reported stronger associations between higher prenatal maternal stress and childhood wheeze in males while the association between postnatal maternal stress and wheeze was stronger among females13. Similarly, Lee and colleagues reported that males were more vulnerable to stress during the prenatal period and females were more impacted by postnatal and cumulative maternal stress when examining asthma risk10.
While the majority of these studies have been conducted in high-income countries, maternal stress and depression is of particular concern in low- and middle-income countries given its high prevalence and the limited resources for its diagnosis and management14-16. Furthermore, studies have shown the prevalence of asthma has increased worldwide, especially in non-industrialized countries17, 18. Understanding the impact of timing and duration of symptoms of maternal psychosocial distress during and post pregnancy and the development of childhood respiratory disease would fulfill a research gap. We leveraged existing data from an established population-based prenatally enrolled longitudinal cohort in Mexico City. We examined the association between maternal depression, assessed during pregnancy and postnatally, and the risk of respiratory disease in early childhood. We also examined whether these effects differed by child sex.