Maternal smoking during pregnancy and risks of suicidal acts in young offspring

The developmental origins of suicide mortality: a systematic review of longitudinal studies

Suicide prevention efforts generally target acute precipitants of suicide, though accumulating evidence suggests that vulnerability to suicide is partly established early in life before acute precipitants can be identified. The aim of this systematic review was to synthesize evidence on early life vulnerability to suicide beginning in the prenatal period and extending through age 12. We searched PubMed, Embase, PsycNet, Web of Science, Scopus, Social Services Abstracts, and Sociological Abstracts for prospective studies published through January 2021 that investigated early life risk factors for suicide mortality. The search yielded 13,237 studies; 54 of these studies met our inclusion criteria. Evidence consistently supported the link between sociodemographic (e.g., young maternal age at birth, low parental education, and higher birth order), obstetric (e.g., low birth weight), parental (e.g., exposure to parental death by external causes), and child developmental factors (e.g., exposure to emotional adversity) and higher risk of suicide death. Among studies that also examined suicide attempt, there was a similar profile of risk factors. We discuss a range of potential pathways implicated in these associations and suggest that additional research be conducted to better understand how early life factors could interact with acute precipitants and increase vulnerability to suicide.

Perinatal adversity profiles and suicide attempt in adolescence and young adulthood: longitudinal analyses from two 20-year birth cohort studies

BACKGROUND

We aimed to identify groups of children presenting distinct perinatal adversity profiles and test the association between profiles and later risk of suicide attempt.

METHODS

Data were from the Québec Longitudinal Study of Child Development (QLSCD, N = 1623), and the Avon Longitudinal Study of Parents and Children (ALSPAC, N = 5734). Exposures to 32 perinatal adversities (e.g. fetal, obstetric, psychosocial, and parental psychopathology) were modeled using latent class analysis, and associations with a self-reported suicide attempt by age 20 were investigated with logistic regression. We investigated to what extent childhood emotional and behavioral problems, victimization, and cognition explained the associations.

RESULTS

In both cohorts, we identified five profiles: No perinatal risk, Poor fetal growth, Socioeconomic adversity, Delivery complications, Parental mental health problems (ALSPAC only). Compared to children with No perinatal risk, children in the Poor fetal growth (pooled estimate QLSCD-ALSPAC, OR 1.89, 95% CI 1.04-3.44), Socioeconomic adversity (pooled-OR 1.42, 95% CI 1.08-1.85), and Parental mental health problems (OR 1.74, 95% CI 1.27-2.40), but not Delivery complications, profiles were more likely to attempt suicide. The proportion of this effect mediated by the putative mediators was larger for the Socioeconomic adversity profile compared to the others.

CONCLUSIONS

Perinatal adversities associated with suicide attempt cluster in distinct profiles. Suicide prevention may begin early in life and requires a multidisciplinary approach targeting a constellation of factors from different domains (psychiatric, obstetric, socioeconomic), rather than a single factor, to effectively reduce suicide vulnerability. The way these factors cluster together also determined the pathways leading to a suicide attempt, which can guide decision-making on personalized suicide prevention strategies.

Prenatal origins of suicide mortality: A prospective cohort study in the United States

Most suicide research focuses on acute precipitants and is conducted in high-risk populations. Yet, vulnerability to suicide is likely established years prior to its occurrence. In this study, we aimed to investigate the risk of suicide mortality conferred by prenatal sociodemographic and pregnancy-related factors. Offspring of participants (N = 49,853) of the Collaborative Perinatal Project, a U.S. population-based cohort of pregnancies enrolled between 1959 and 1966, were linked to the U.S. National Death Index to determine their vital status by the end 2016. We examined associations between sociodemographic factors during pregnancy, pregnancy complications, labor and delivery complications, and neonatal complications with suicide death coded according to ICD-9/10 criteria. By the end of 2016, 3,555 participants had died. Of these, 288 (214 males, 74 females) died by suicide (incidence rate = 15.6 per 100,000 person-years, 95% Confidence Interval [CI] = 13.9-17.5). In adjusted models, male sex (Hazard Ratio [HR] = 2.98, CI: 2.26-3.93), White race (HR = 2.14, CI = 1.63-2.83), low parental education (HR = 2.23, CI = 1.38-3.62), manual parental occupation (HR = 1.38, CI = 1.05-1.82), being a younger sibling (HR = 1.52, CI = 1.10-2.11), higher rates of pregnancy complications (HR = 2.36, CI = 1.08-5.16), and smoking during pregnancy (HR = 1,28, CI = 0.99-1.66) were independently associated with suicide risk, whereas birth and neonatal complications were not. Consistent with the developmental origins of psychiatric disorders, vulnerability to suicide mortality is established early in development. Both sociodemographic and pregnancy factors play a role in this risk, which underscores the importance of considering life course approaches to suicide prevention, possibly including provision of high-quality prenatal care, and alleviating the socioeconomic burdens of mothers and families.

Suicidal ideation and attempt in adolescents exposed to maternal smoking across pregnancy and childhood: A 20-year prospective cohort study

BACKGROUND

Few studies investigated the association between maternal smoking during pregnancy and offspring suicide risk, none considering postnatal smoking exposure. We investigated associations between maternal smoking patterns during the pre- and postnatal periods and adolescent suicidal ideation and attempt.

METHODS

We identified longitudinal patterns of maternal smoking from the prenatal period to the end of childhood (children's age 12 years, 10 assessments) among participants in the Québec Longitudinal Study of Child Development (N = 1623). We estimated associations between maternal smoking patterns and offspring self-reported suicidal ideation and attempt (ages 13-20). Background confounding factors (e.g., socioeconomic, familial, mental health) were controlled using propensity score inverse-probability weighting (IPW).

RESULTS

Participants reporting suicidal ideation and attempt were 9.3% and 8.4%, respectively. We identified four maternal smoking patterns: non-smoking (66.5%), increasing (5.5%), decreasing (9.3%), persistent (18.5%). Children exposed to persistent (OR=2.92, CI=1.99-4.30) and increasing (OR=2.06, CI=1.13-3.74) maternal smoking were more likely to attempt suicide, compared to non-exposed children. Accounting for confounding factors using IPW fully explained the association between increasing smoking and suicide attempt (OR=0.95, CI=0.39-2.09) but only reduced the association between persistent exposure and suicide attempt (OR=2.30, CI=1.04-4.99). No increased suicide attempt risk was found for children of mothers with a decreased smoking pattern. We found no associations for suicidal ideation.

LIMITATIONS

Propensity score cannot account for unmeasured confounding factors; attrition limits generalizability.

CONCLUSIONS

Offspring of mothers who smoked persistently and heavily prenatally and postnatally were at increased risk of suicide attempt in adolescence. Future studies should elucidate biological and psychosocial mechanisms potentially at play in these associations.

Preterm birth, low fetal growth and risk of suicide in adulthood: a national cohort and co-sibling study

BACKGROUND

Adverse perinatal exposures have been associated with psychiatric disorders and suicidal behaviours later in life. However, the independent associations of gestational age at birth or fetal growth with suicide death, potential sex-specific differences, and causality of these associations are unclear.

METHODS

A national cohort study was conducted of all 2 440 518 singletons born in Sweden during 1973-98 who survived to age 18 years, who were followed up through 2016. Cox regression was used to compute hazard ratios (HRs) for suicide death associated with gestational age at birth or fetal growth while mutually adjusting for these factors, sociodemographic characteristics and family history of suicide. Co-sibling analyses assessed the influence of unmeasured shared familial (genetic and/or environmental) factors.

RESULTS

In 31.2 million person-years of follow-up, 4470 (0.2%) deaths by suicide were identified. Early preterm birth (22-33 weeks) was associated with an increased risk of suicide among females [adjusted hazard ratio (HR), 1.97; 95% confidence interval CI), 1.29, 3.01; P = 0.002) but not males (0.90; 0.64, 1.28; P = 0.56), compared with full-term birth (39-41 weeks). Small for gestational age was associated with a modestly increased risk of suicide among females (adjusted HR, 1.27; 95% CI, 1.08, 1.51; P = 0.005) and males (1.14; 1.03, 1.27; P = 0.02). However, these associations were attenuated and non-significant after controlling for shared familial factors.

CONCLUSIONS

In this large national cohort, preterm birth in females and low fetal growth in males and females were associated with increased risks of suicide death in adulthood. However, these associations appeared to be non-causal and related to shared genetic or prenatal environmental factors within families.

Machine Learning Assessment of Early Life Factors Predicting Suicide Attempt in Adolescence or Young Adulthood

IMPORTANCE

Although longitudinal studies have reported associations between early life factors (ie, in-utero/perinatal/infancy) and long-term suicidal behavior, they have concentrated on 1 or few selected factors, and established associations, but did not investigate if early-life factors predict suicidal behavior.

OBJECTIVE

To identify and evaluate the ability of early-life factors to predict suicide attempt in adolescents and young adults from the general population.

DESIGN, SETTING, AND PARTICIPANTS

This prognostic study used data from the Québec Longitudinal Study of Child Development, a population-based longitudinal study from Québec province, Canada. Participants were followed-up from birth to age 20 years. Random forest classification algorithms were developed to predict suicide attempt. To avoid overfitting, prediction performance indices were assessed across 50 randomly split subsamples, and then the mean was calculated. Data were analyzed from November 2019 to June 2020.

EXPOSURES

Factors considered in the analysis included 150 variables, spanning virtually all early life domains, including pregnancy and birth information; child, parents, and neighborhood characteristics; parenting and family functioning; parents' mental health; and child temperament, as assessed by mothers, fathers, and hospital birth records.

MAIN OUTCOMES AND MEASURES

The main outcome was self-reported suicide attempt by age 20 years.

RESULTS

Among 1623 included youths aged 20 years, 845 (52.1%) were female and 778 (47.9%) were male. Models show moderate prediction performance. The areas under the curve for the prediction of suicide attempt were 0.72 (95% CI, 0.71-0.73) for females and 0.62 (95% CI, 0.60-0.62) for males. The models showed low sensitivity (females, 0.50; males, 0.32), moderate positive predictive values (females, 0.60; males, 0.62), and good specificity (females, 0.76; males, 0.82) and negative predicted values (females, 0.75; males, 0.71). The most important factors contributing to the prediction included socioeconomic and demographic characteristics of the family (eg, mother and father education and age, socioeconomic status, neighborhood characteristics), parents' psychological state (specifically parents' antisocial behaviors) and parenting practices. Birth-related variables also contributed to the prediction of suicidal behavior (eg, prematurity). Sex differences were also identified, with family-related socioeconomic and demographic characteristics being the top factors for females and parents' antisocial behavior being the top factor for males.

CONCLUSIONS AND RELEVANCE

These findings suggest that early life factors contributed modestly to the prediction of suicidal behavior in adolescence and young adulthood. Although these factors may inform the understanding of the etiological processes of suicide, their utility in the long-term prediction of suicide attempt was limited.

In-utero and perinatal influences on suicide risk: a systematic review and meta-analysis

BACKGROUND

Adverse in-utero and perinatal conditions might contribute to an increased suicide risk throughout the lifespan; however, existing evidence is sparse and contradictory. We aimed to investigate in-utero and perinatal exposures associated with suicide, suicide attempt, and suicidal ideation.

METHODS

We did a systematic review and meta-analysis and searched MEDLINE, Embase, and PsycINFO from inception to Jan 24, 2019, for population-based prospective studies that investigated the association between in-utero and perinatal factors and suicide, suicide attempt, and suicidal ideation. Only papers published in English in peer-reviewed journals were considered. Two researchers independently extracted formal information (eg, country, year, duration of follow-up) and number of cases and non-cases exposed and non-exposed to each risk factor. We calculated pooled odds ratios (ORs) with 95% CIs using random-effects models and used meta-regression to investigate heterogeneity. This study was registered with PROSPERO, number CRD42018091205.

FINDINGS

We identified 42 eligible studies; they had a low risk of bias (median quality score 9/9 [IQR 8-9]). Family or parental characteristics, such as high birth order (eg, for fourth-born or later-born vs first-born, pooled OR 1·51 [95% CIs 1·21-1·88]), teenage mothers (1·80 [1·52-2·14]), single mothers (1·57 [1·31-1·89]); indices of socioeconomic position, such as low maternal (1·36 [1·28-1·46]) and paternal (1·38 [1·27-1·51]) education; and fetal growth (eg, low birthweight 1·30 [1·09-1·55] and small for gestational age 1·18 [1·00-1·40]) were associated with higher suicide risk. Father's age, low gestational age, obstetric characteristics (eg, caesarean section), and condition or exposure during pregnancy (eg, maternal smoking or hypertensive disease) were not associated with higher suicide risk. Similar patterns of associations were observed for suicide attempt and suicidal ideation; however, these results were based on a lower number of studies. In meta-regression, differences in length of follow-up explained most between-study heterogeneity (inital I² ranged from 0 to 79·5).

INTERPRETATION

These findings suggest that prenatal and perinatal characteristics are associated with increased suicide risk during the life course, supporting the developmental origin of health and diseases hypothesis for suicide. The low number of studies for some risk factors, especially for suicide attempt and ideation, leaves gaps in knowledge that need to be addressed. The mechanisms underlying the reported associations and their causal nature still remain unclear.

FUNDING

Horizon 2020 (EU).

The Rotterdam Study: 2014 objectives and design update

The Rotterdam Study is a prospective cohort study ongoing since 1990 in the city of Rotterdam in The Netherlands. The study targets cardiovascular, endocrine, hepatic, neurological, ophthalmic, psychiatric, dermatological, oncological, and respiratory diseases. As of 2008, 14,926 subjects aged 45 years or over comprise the Rotterdam Study cohort. The findings of the Rotterdam Study have been presented in over a 1,000 research articles and reports (see www.erasmus-epidemiology.nl/rotterdamstudy ). This article gives the rationale of the study and its design. It also presents a summary of the major findings and an update of the objectives and methods.

Critical need for family-based, quasi-experimental designs in integrating genetic and social science research

Researchers have identified environmental risks that predict subsequent psychological and medical problems. Based on these correlational findings, researchers have developed and tested complex developmental models and have examined biological moderating factors (e.g., gene-environment interactions). In this context, we stress the critical need for researchers to use family-based, quasi-experimental designs when trying to integrate genetic and social science research involving environmental variables because these designs rigorously examine causal inferences by testing competing hypotheses. We argue that sibling comparison, offspring of twins or siblings, in vitro fertilization designs, and other genetically informed approaches play a unique role in bridging gaps between basic biological and social science research. We use studies on maternal smoking during pregnancy to exemplify these principles.

Familial confounding of the association between maternal smoking during pregnancy and offspring substance use and problems

CONTEXT

Previous epidemiological, animal, and human cognitive neuroscience research suggests that maternal smoking during pregnancy (SDP) causes increased risk of substance use/problems in offspring.

OBJECTIVE

To determine the extent to which the association between SDP and offspring substance use/problems depends on confounded familial background factors by using a quasi-experimental design.

DESIGN

We used 2 separate samples from the United States and Sweden. The analyses prospectively predicted multiple indices of substance use and problems while controlling for statistical covariates and comparing differentially exposed siblings to minimize confounding.

SETTING

Offspring of a representative sample of women in the United States (sample 1) and the total Swedish population born during the period from January 1, 1983, to December 31, 1995 (sample 2).

PATIENTS OR OTHER PARTICIPANTS

Adolescent offspring of the women in the National Longitudinal Survey of Youth 1979 (n = 6904) and all offspring born in Sweden during the 13-year period (n = 1,187,360).

MAIN OUTCOME MEASURES

Self-reported adolescent alcohol, cigarette, and marijuana use and early onset (before 14 years of age) of each substance (sample 1) and substance-related convictions and hospitalizations for an alcohol- or other drug-related problem (sample 2).

RESULTS

The same pattern emerged for each index of substance use/problems across the 2 samples. At the population level, maternal SDP predicted every measure of offspring substance use/problems in both samples, ranging from adolescent alcohol use (hazard ratio [HR](moderate), 1.32 [95% CI, 1.22-1.43]; HR(high), 1.33 [1.17-1.53]) to a narcotics-related conviction (HR(moderate), 2.23 [2.14-2.31]; HR(high), 2.97 [2.86-3.09]). When comparing differentially exposed siblings to minimize genetic and environmental confounds, however, the association between SDP and each measure of substance use/problems was minimal and not statistically significant.

CONCLUSIONS

The association between maternal SDP and offspring substance use/problems is likely due to familial background factors, not a causal influence, because siblings have similar rates of substance use and problems regardless of their specific exposure to SDP.

The Generation R Study: design and cohort update 2012

The Generation R Study is a population-based prospective cohort study from fetal life until adulthood. The study is designed to identify early environmental and genetic causes and causal pathways leading to normal and abnormal growth, development and health during fetal life, childhood and adulthood. The study focuses on six areas of research: (1) maternal health; (2) growth and physical development; (3) behavioural and cognitive development; (4) respiratory health and allergies; (5) diseases in childhood; and (6) health and healthcare for children and their parents. Main exposures of interest include environmental, endocrine, genetic and epigenetic, lifestyle related, nutritional and socio-demographic determinants. In total, n = 9,778 mothers with a delivery date from April 2002 until January 2006 were enrolled in the study. Response at baseline was 61 %, and general follow-up rates until the age of 6 years exceed 80 %. Data collection in mothers, fathers and children include questionnaires, detailed physical and ultrasound examinations, behavioural observations, and biological samples. A genome and epigenome wide association screen is available in the participating children. From the age of 5 years, regular detailed hands-on assessments are performed in a dedicated research center including advanced imaging facilities such as Magnetic Resonance Imaging. Eventually, results forthcoming from the Generation R Study contribute to the development of strategies for optimizing health and healthcare for pregnant women and children.

Perinatal conditions and parental age at birth as risk markers for subsequent suicide attempt and suicide: a population based case-control study

Restricted fetal growth and young maternal age have been associated with increased risk of suicidal behaviour later in life. Research investigating the independent and interacting effects of these risk factors with parental mental health and socio-economic status is scarce. A case-control study was effected through record linkage between Swedish registers. Individuals born 1973-1983 who were hospitalized due to a suicide attempt (n = 17,159) or committed suicide (n = 1,407) were matched to ≤10 controls by sex, month and county of birth. Controlling for parental conditions, significantly increased odds ratios (OR) for suicide attempt were found for low birth weight (OR = 1.12, 95 % CI 1.01-1.25), short birth length (OR = 1.15, 95 % CI 1.08-1.22), short and light for gestational age (OR = 1.23, 95 % CI: 1.10-1.38), short but not light for gestational age (OR = 1.18, 95 % CI: 1.09, 1.29), teenage motherhood (OR = 1.66, 95 % CI 1.53-1.80), young fatherhood (OR = 1.33, 95 % CI 1.27-1.39) and multiparity (OR = 1.40, 95 % CI 1.31-1.50). For completed suicide, increased odds ratios were found for low birth weight (OR = 1.65, 95 % CI 1.16-2.35), teenage motherhood (OR = 1.44, 95 % CI 1.09-1.90) and young fatherhood (OR = 1.20, 95 % CI 1.02-1.41). There was a synergy effect between teenage motherhood and parental psychiatric inpatient care with regard to suicide attempt in offspring [synergy index = 1.53 (95 % CI 1.27-1.84)]. Low birth weight and length, and short and light for gestational age may increase the risk of subsequent suicidal behaviour, and more research is needed to investigate underlying mechanisms. Public health implications from this study include measures to improve pre- and perinatal parental mental health, particularly in teenage pregnancies.

Fetal and infant origins of asthma

Previous studies have suggested that asthma, like other common diseases, has at least part of its origin early in life. Low birth weight has been shown to be associated with increased risks of asthma, chronic obstructive airway disease, and impaired lung function in adults, and increased risks of respiratory symptoms in early childhood. The developmental plasticity hypothesis suggests that the associations between low birth weight and diseases in later life are explained by adaptation mechanisms in fetal life and infancy in response to various adverse exposures. Various pathways leading from adverse fetal and infant exposures to growth adaptations and respiratory health outcomes have been studied, including fetal and early infant growth patterns, maternal smoking and diet, children's diet, respiratory tract infections and acetaminophen use, and genetic susceptibility. Still, the specific adverse exposures in fetal and early postnatal life leading to respiratory disease in adult life are not yet fully understood. Current studies suggest that both environmental and genetic factors in various periods of life, and their epigenetic mechanisms may underlie the complex associations of low birth weight with respiratory disease in later life. New well-designed epidemiological studies are needed to identify the specific underlying mechanisms. This review is focused on specific adverse fetal and infant growth patterns and exposures, genetic susceptibility, possible respiratory adaptations and perspectives for new studies.