Happiness and Depression in Adolescence after Maternal Smoking during Pregnancy: Birth Cohort Study

et al. (2013) Happiness and Depression in Adolescence after Maternal Smoking during Pregnancy: Birth Cohort Study. PLoS ONE 8(11): e80370. doi:10.1371/journal.pone.0080370 Happiness and Depression in Adolescence after Maternal Smoking during Pregnancy: Birth Cohort Study Ana Maria Baptista Menezes 0 Joseph Murray 0 Mitzi Lszl 0 Fernando C. Wehrmeister 0 Pedro C. 0 Hallal 0 Helen Gonalves 0 Maria Cecilia F. Assuno 0 Carolina Baptista Menezes 0 Fernando C. Barros 0 Sreeram V. Ramagopalan, University of Oxford, United Kingdom 0 1 Post-Graduate Program in Epidemiology, Federal University of Pelotas , Pelotas, Rio Grande do Sul , Brazil , 2 Department of Psychiatry, Cambridge, United Kingdom, 3 Department of Psychology, Federal University of Pelotas , Pelotas, Rio Grande do Sul , Brazil , 4 Post-Graduate Program in Health and Behavior, Catholic University of Pelotas , Pelotas, Rio Grande do Sul , Brazil Background: Prenatal cigarette smoke exposure may have adverse psychological effects on offspring. The objective was to assess the association between parental smoking during pregnancy and offspring happiness at age 18, as well as depression. Methodology: Participants were part of a birth cohort study in Pelotas, Brazil (5,249 participants). Happiness was measured by the Subjective Happiness Scale, a Likert-like scale with four questions generating a score from 1 to 7, with 6 indicating "happiness". Depression was measured using the Mini International Psychiatric Interview. Results: About one third of mothers reported having smoked during pregnancy and 4.6% reported smoking 20 or more cigarettes a day. The prevalence of happiness was 32.2% (95% CI 30.8; 33.7), depression 6.8% (95% CI 6.1; 7.6), and simultaneous happiness and depression less than 1%. The prevalence of offspring happiness decreased as smoking in pregnancy increased, even after control for confounding variables, showing an OR = 0.79 [95% CI 0.55; 1.13]. The opposite happened to depression; the prevalence of offspring depression increased as smoking in pregnancy increased (<20 cigarettes/day OR = 1.38 [95% CI 1.03; 1.84] and 20 cigarettes/day OR = 2.11[95% CI 1.31; 3.40]. Smoking by the partner was associated with decreased offspring happiness after adjustment for confounders, but did no show association with offspring depression. Conclusions: Offspring were less likely to be happy and more likely to be depressed if their mother smoked during pregnancy, and less likely to be happy if their father smoked during mother's pregnancy. Although we can not affirm that this is a causal pathway, public policies to reduce smoking in pregnancy could improve the health of the offspring in the short and long term. - Funding: This work was supported by the Wellcome Trust initiative: Major Awards for Latin America on Health Consequences of Population Change [grant number 086974/Z/08/Z]. Earlier phases of the 1993 cohort study were funded by the European Union, the National Program for Centers of Excellence (Brazil), the National Research Council (Brazil) and the Ministry of Health (Brazil). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing interests: The authors have declared that no competing interests exist. There is evidence that prenatal cigarette smoke exposure can have short- and long-term adverse psychological effects on offspring, both in human [1,2] and animal studies [3]. Previous studies have tended to focus on the association between cigarette smoke exposure during pregnancy and externalizing behavioural problems, such as aggression, attention deficits and substance use in children have all been linked to prenatal exposure to tobacco smoke [4,5]. It has been demonstrated that in adults aged 22, externalizing and internalizing problems are associated with prenatal exposure to tobacco, even after controlling for potential confounders, such as parental mental demographic variables [1]. However, this association is not consistent across ages. Other longitudinal assessments of offspring at ages 4 [6], 5 [7], 10 [8], 14 [9], and 11-13-16 [10] failed to detect associations with internalizing problems, even many showed an association between tobacco exposure and externalizing and attention problems [6,7,9]. Recently, there has been a focus on the study of happiness as a separate phenomenon to depression and internalizing problems. Happiness is conceptualised as an important outcome in its own right, distinct from the absence of depressive disorder, possibly with its own specific causal mechanisms [11]. It has been demonstrated that lower levels of happiness and well-being are associated with increased mortality [12] and greater risk of chronic illnesses [13]. Given the social and economic impact of poor mental health worldwide, and growing recognition of the importance of happiness or well being, the value of prevention and early intervention is highly emphasised [14]. We found no studies that have assessed the association between prenatal exposure to tobacco and happiness. Smoking during pregnancy could be one possible preventable risk factor for the development of maladaptive emotional functioning among offspring. There is no consensus in the literature on the underlying biological pathway involved in the association of maternal smoking during pregnancy and some outcomes in children or adolescents. As has been pointed out by several authors [1518], one of the difficulties for the interpretation of results from several studies is to disentangle prenatal exposures effects from environmental and genetic factors. Animal studies suggest a direct effect of maternal smoking during pregnancy and mood changes through a decrease in certain neurotransmitters as a result of prenatal nicotine exposure. Using a birth cohort design, the primary aim of this study was to assess the association between cigarette smoke exposure during pregnancy with happiness of the teenager at age 18, taking into account the role of confounding and mediating factors. Importantly, unhappy people were not considered necessarily depressed, and happiness and depression were analysed as two separate outcomes. Depression is associated with internalizing behavioral problems and can be a very disabling condition, associated with many negative outcomes, including impaired social, educational, occupational, and familial functioning [19]. In the calendar year of 1993, all deliveries taking place in the four hospitals of the city of Pelotas, Brazil were monitored. All mothers who lived in the urban area of the city at that time were invited to participate in a research project, in which newborns would be followed up from birth to adult life. All but 16 mothers agreed to take part, resulting in a total cohort size of 5,249 individuals. Within 24 hours of delivery, mothers answered a questionnaire and newborns underwent a series of anthropometric measurements. The questi (...truncated)