How to Promote a Stress and Smoke Free Start of Life?
Authors:   , van Dijk Willeke 
Published: September 2024

This dissertation consists of two parts. Part I focuses on perinatal stress and smoking and part II focuses on parenting stress and child internalizing and externalizing behaviors. The findings of all studies are summarized below.
Following chapter 1, a general introduction to the contents of this dissertation, chapter 2 describes the protocol of the RCT aiming to test the effectiveness of the eHealth intervention on smoking cessation, smoking reduction, and perceived stress reduction. This protocol describes that the intervention (eHealth intervention) is an 8-week intervention delivered on the participant’s smartphone, consisting of psycho-education on pregnancy, stress, and smoking (cessation); stress-management training including HRV-BF; and a personalized stop-smoking-plan. The control condition of the RCT includes a webpage with a summarized version of the psycho-education as in the eHealth intervention.
Chapter 3 presents the findings of a validation study to examine whether heart rate variability as used to offer HRV-BF training, could be reliably assessed using photoplethysmography via a smartphone. Based on these results, it can be concluded that heart rate variability can reliably be measured via PPG during HRV-BF. The effectiveness of an 8 week eHealth intervention that included the HRV-BF module, as validated in chapter 3, is reported in chapters 4 and 5.
Chapter 4 shows the results of an intervention study, investigating the effectiveness the eHealth intervention on smoking cessation, smoking reduction, and perceived stress reduction in pregnant smoking women. The results demonstrated that both the intervention and the control condition improved with regard to smoking, as demonstrated by a reduction in smoking frequency (average number of smoking days per week) and smoking quantity (average number of cigarettes smoked per week). Moreover, it was shown that the intervention was not more effective on smoking cessation, smoking reduction, or perceived stress reduction
than the active control condition since no difference in these outcomes was found between the two groups. Furthermore, the findings indicate that women who were more motivated to quit smoking at the start of the study were more likely to reduce the number of smoking days per week (smoking frequency) and the number of cigarettes smoked per week on average (smoking quantity). Moreover, a dose‒response effect of program usage on reducing smoking frequency and smoking quantity was demonstrated, indicating that when women used the intervention more frequently, a greater reduction in these outcomes was found.
Chapter 5 shows that the intervention and control condition did not differ in birth outcomes (birth weight, gestational age at birth, 1-minute Apgar scores, birth and postpartum complications, and infant negative affectivity). Also, babies born to women who successfully quit smoking during pregnancy and those born to women who did not did not quit did not differ in terms of these outcomes. Additionally, smoking reduction and stress reduction were not associated with birth outcomes or infant behavioral outcomes.
Chapter 6, a longitudinal study based on a sample derived from the Growing Up in Ireland National Longitudinal Study of Children (GUI), shows that parenting stress when children were 5 years old predicted child internalizing behaviors at age 9, and child externalizing behaviors at age 3 predicted parenting stress at age 5. Moreover, it was demonstrated that parenting stress and child externalizing behaviors were bidirectionally associated from age 5 to 9. Neither parental warmth nor parental hostility explained the associations between parenting stress and child internalizing and externalizing behaviors across the period from the child’s age 3 to 9.
Strengths and limitations, suggestions for future research and intervention development, and clinical implications are discussed.