Venla Lehti

Risk of Autism Spectrum Disorders in Low Birth Weight and Small for Gestational Age Infants

OBJECTIVE To examine the relationship between birth weight, gestational age, small for gestational age (SGA), and 3 of the most common autism spectrum disorder (ASD) subtypes. STUDY DESIGN In this population-based case-control study conducted in Finland, 4713 cases born between 1987 and 2005 with International Classification of Diseases-diagnoses of childhood autism, Asperger syndrome, or pervasive developmental disorder (PDD), were ascertained from the Finnish Hospital Discharge Register. Four controls, individually matched on sex, date of birth, and place of birth, were selected from the Finnish Medical Birth Register for each case. Conditional logistic regression models were used to assess whether birth weight and gestational age information predicted ASD after controlling for maternal age, parity, smoking during pregnancy, and psychiatric history, as well as for infants major congenital anomalies. RESULTS Very low (<1500 g) and moderately low (<2500 g) birth weight, very low gestational age (less than 32 weeks), and SGA increased risk of childhood autism (adjusted OR 3.05, 95% CI 1.4-6.5; 1.57, 1.1-2.3; 2.51, 1.3-5.0; and 1.72, 1.1-2.6, respectively). Very low and moderately low birth weight, very low gestational age, and SGA were also associated with increase in PDD risk (OR 3.44, 95% CI 1.9-6.3; 1.81, 1.4-2.4; 2.46, 1.4-2.3; and 2.24, 1.7-3.0, respectively). No associations were found between the perinatal characteristics and Asperger syndrome. The increased risks persisted after controlling for selected potential confounders. CONCLUSIONS The finding that low birth weight, prematurity, and SGA were related to childhood autism and PDD but not to Asperger syndrome suggests that prenatal factors related to these exposures may differ for these ASD subtypes, which may have preventive implications.

Mental health, substance use and suicidal behaviour among young indigenous people in the Arctic: A systematic review

The Arctic has been a subject to various socio-cultural changes; indigenous people living in the region have experienced injustice and oppression in different forms. Furthermore, there are currently various new social, political and environmental challenges. It has been assumed that the continuous socio-cultural transition has an influence on indigenous peoples wellbeing. We conducted a systematic literature review with regard to epidemiological mental health research on Arctic indigenous children and adolescents. The aim was to describe the nature and scope of research conducted and to explore for possible regional and ethnic differences in mental health. It was found that current epidemiological knowledge is based mainly on cross-sectional studies from selected regions and limited to substance use and suicidal behaviour. Youth suicide rates are alarmingly high in many parts of the Arctic, particularly in Greenland and Alaska. Differences between indigenous and non-indigenous groups are also most evident and uniform across suicide studies, with rates being systematically higher among indigenous youth. Substance use is common throughout the Arctic, however, regional and ethnic differences in usage vary considerably. Other psychosocial problems remain largely unexplored. In addition, very little is known about the causes of mental health problems in general and the impact of rapid socio-cultural changes in particular. There are several methodological limitations in the studies included here, many related to the validity of research instruments in different cultural contexts. There is a need for longitudinal comparative studies from the entire Arctic with culturally relevant instruments addressing mental health in early childhood as well.

Smoking during Pregnancy and Risk of Autism Spectrum Disorder in a Finnish National Birth Cohort

BACKGROUND Results of previous population-based studies examining associations between smoking during pregnancy and autism spectrum disorders (ASD) are contradictory. Furthermore, there is a lack of population-based studies examining the relationship between smoking during pregnancy and the main diagnostic subtypes of ASD. METHODS We conducted a population-based nested case-control study based on the Finnish Prenatal Study of Autism (FIPS-A) among liveborn infants delivered in Finland between 1987 and 2005. Data on maternal smoking during pregnancy were available from the Finnish Medical Birth Register (FMBR) since October 1990. Data on ASD in the offspring were obtained from the Finnish Hospital Discharge Register (FHDR). RESULTS Among the three subtypes of ASD, maternal smoking during the whole pregnancy was associated with an increased risk of pervasive developmental disorder (PDD) (odds ratio 1.2, 95% confidence interval 1.0, 1.5). The increase in odds persisted after controlling for maternal age, mothers socio-economic and psychiatric status, and infants weight for gestational age. However, smoking exposure limited to the first trimester was not associated with PDD or any of the other ASD subtypes. CONCLUSIONS Maternal smoking is related to a modest increase in risk of PDD, while no associations were observed for childhood autism and Aspergers syndrome.

Childhood bullying as a predictor for becoming a teenage mother in Finland.

The aim of this study is to examine the association between bullying behaviour at the age of 8 and becoming a mother under the age of 20. This birth cohort study included 2,867 Finnish girls at baseline in 1989. Register-based follow-up data on births was collected until the end of 2001. Information, both on the main exposure and outcome, was available for 2,507 girls. Both bullies and victims had an increased risk of becoming a teenage mother independent of family-related risk factors. When controlled for childhood psychopathology, however, the association remained significant for bullies (OR 2.2, 95% CI 1.2–4.1) and bully-victims (OR 1.8, 95% CI 1.05–3.2), but not for pure victims. Reports of bullying and victimisation from the girls themselves, their parents and their teachers were all associated with becoming a teenage mother independent of each other. There is a predictive association between being a bully in childhood and becoming a mother in adolescence. It may be useful to target bullies for teenage pregnancy prevention.

Parental age and the risk of attention-deficit/hyperactivity disorder: a nationwide, population-based cohort study.

OBJECTIVE An increasing number of studies has shown an association between parental age and psychiatric disorders. However, there are inconsistent results regarding whether age at parenthood is associated with attention-deficit/hyperactivity disorder (ADHD). The aim of this study is to examine whether low or advanced parental age is associated with ADHD. METHOD In this nested case-control study, we identified 10,409 individuals with ADHD born in Finland during 1991 to 2005 and diagnosed with ADHD between 1995 and 2011, along with 39,125 controls matched on sex, date, and place of birth, from nationwide population-based registers. Conditional logistic regression was used to examine the association between parental age and ADHD in offspring, adjusting for potential confounding due to parental psychiatric history, maternal socioeconomic status, marital status, maternal smoking during pregnancy, number of previous births, and birth weight for gestational age. RESULTS Fathers younger than 20 years had a 1.5-fold (odds ratio [OR] = 1.55, 95% CI = 1.11-2.18, p = .01) increased risk of having offspring with ADHD as compared to fathers aged 25 to 29 years. Mothers of the same age group had a 1.4-fold (OR = 1.41, 95% CI = 1.15-1.72, p =.0009) increased risk. Advanced maternal age was inversely associated with ADHD (OR = 0.79, 95% CI = 0.64-0.97, p = .02). CONCLUSION ADHD was associated with young fathers or mothers at the time of birth. Health professionals working with young parents should be aware of the increased risk of ADHD in offspring. This will improve early detection; however, for the development of preventive measures and appropriate interventions, more information on the developmental pathways is needed.

Perinatal factors and the risk of bipolar disorder in Finland.

BACKGROUND Complications during the perinatal period have been associated with neurodevelopmental disorders like schizophrenia and autism. However, similar studies on bipolar disorder (BPD) have been limited and the findings are inconsistent. The aim of this study was to examine the association between perinatal risk factors and BPD. METHODS This nested case-control study, based on the Finnish Prenatal Study of Bipolar Disorders (FIPS-B), identified 724 cases and 1419 matched controls from population based registers. Conditional logistic regression was used to examine the associations between perinatal factors and BPD adjusting for potential confounding due to maternal age, psychiatric history and educational level, place of birth, number of previous births and maternal smoking during pregnancy. RESULTS Children delivered by planned cesarean section had a 2.5-fold increased risk of BPD (95% CI: 1.32-4.78, P<0.01). No association was seen between other examined perinatal risk factors and BPD. LIMITATIONS The limitations of this study include: the restriction in the sample to treated cases of BPD in the population, and usage of hospital based clinical diagnosis for case ascertainment. In addition, in spite of the large sample size, there was low power to detect associations for certain exposures including the lowest birth weight category and pre-term birth. CONCLUSIONS Birth by planned cesarean section was associated with risk of BPD, but most other perinatal risk factors examined in this study were not associated with BPD. Larger studies with greater statistical power to detect less common exposures and studies utilizing prospective biomarker-based exposures are necessary in the future.

The risk of childhood autism among second-generation migrants in Finland: a case-control study

BackgroundStudying second-generation immigrants can help in identifying genetic or environmental risk factors for childhood autism. Most previous studies have focused on maternal region of birth and showed inconsistent results. No previous study has been conducted in Finland.MethodsThe study was a nested case–control study based on a national birth cohort. Children born in 1987–2005 and diagnosed with childhood autism by the year 2007 were identified from the Finnish Hospital Discharge Register. Controls were selected from the Finnish Medical Birth Register. Information on maternal and paternal country of birth and mother tongue was collected from the Finnish Central Population Register. There were 1132 cases and 4515 matched controls. The statistical test used was conditional logistic regression analysis.ResultsCompared with children with two Finnish parents, the risk of childhood autism was increased for those whose parents are both immigrants (adjusted odds ratio [aOR] 1.8, 95% confidence interval [CI] 1.2–2.7) and for those with only an immigrant mother (aOR 1.8, 95% CI 1.2–2.7), but not for those with only an immigrant father. The risk was increased for those with a mother born in the former Soviet Union or Yugoslavia and for those with a mother or a father born in Asia. Specific parental countries of birth associated with an increased risk were the former Soviet Union, the former Yugoslavia and Vietnam.ConclusionsIn Finland, children who are born to immigrant mothers with or without an immigrant partner, have an increased risk of childhood autism. The risk varies with immigrant parents’ region of birth. The findings may help in identifying possible risk factors, which can be examined in future studies.

Childhood predictors of becoming a teenage mother among Finnish girls

Objective. To study predictive associations between psychosocial factors at age 8 and becoming a mother under the age of 20. Design: Prospective follow‐up study. Setting: Finland. Population. 2867 girls born in 1981. Methods. Information on family background and psychiatric symptoms was collected at age 8. The associations between these factors and becoming a teenage mother were analyzed using logistic regression analysis. Main outcome measures. Data on births by the age of 20 collected from the hospital discharge register. Results. 128 girls (4.8%) had given birth at the age of 15–19 years. Childhood conduct problems and hyperactive problems, having young mother and family structure other than two biological parents had an independent association with becoming a teenage mother. Conclusions. Girls with externalizing type of problems in childhood have an increased risk of becoming teenage mothers. These problems may also complicate their motherhood.

Parental age and the risk of bipolar disorders.

Studies on the association between parental age and bipolar disorder (BPD) are scarce and with inconsistent findings. The aim of this study was to examine the association of parental age and age difference between parents with risk of BPD in offspring.

Finnish Prenatal Study of Bipolar Disorders (FIPS-B): Overview, design and description of the sample

Abstract Background: Bipolar disorders (BPD) are chronic mental illnesses, the development of which involves genetic factors and environmental influences. Aims: The aim of this paper is to provide an overall description of the Finnish Prenatal Study of Bipolar Disorders (FIPS-B), including the study design, national registers and linkage of the registers. Methods: FIPS-B is a population-based prenatal epidemiological study of BPD with a nested case–control study design using several national registers. The registers used are: the Finnish Medical Birth Register (FMBR), the Finnish Hospital Discharge Register (FHDR), the Population Central Register and the Finnish Maternity Cohort (FMC), which are linked using the unique personal identity code (PIC). FIPS-B includes all children born from January 1, 1983 to December 31, 1998 and diagnosed with BPD in Finland by December 31, 2008. Results: The total number of cases included in the FIPS-B is 1887. The age at first diagnosis ranged from 4 to 25 years. Half (50.4%) of the cases utilized only outpatient services, 12.7% only inpatient services and the rest (36.9%) utilized both services. Offspring of mothers with the lowest educational level had an increased odds of BPD (OR = 1.46, 95% CI 1.13–1.88). The cumulative incidence of BPD in the population aged 25 years or younger was 11.6/10,000 in 2008. Conclusions:  FIPS-B has all the strengths of a register-based prenatal epidemiological study, along with the availability of maternal biomarkers, enabling it to examine several prenatal, perinatal and familial risk factors for BPD.