Continuity of antipsychotic medication use among migrant and Finnish-born populations with a psychotic disorder: a register-based study.

BACKGROUND: Higher incidence of psychotic disorders and underuse of mental health services have been reported among many migrant populations. This study examines the initiation and continuity of antipsychotic treatment among migrants and non-migrants with a non-affective psychosis during a new treatment episode. METHODS: This study is based on a nationwide sample of migrants and Finnish-born controls. Participants who were diagnosed with a psychotic disorder in 2011-2014 were identified from the Care Register for Health Care (n = 1693). Information on purchases of antipsychotic drugs in 2011-2015 was collected from the National Prescription Register. The duration of antipsychotic treatment since diagnosis was estimated using the PRE2DUP model. Cox regression analysis was used to study factors that are associated with discontinuing the use of medication. RESULTS: There were fewer initiators of antipsychotic treatment after being diagnosed with psychosis among migrants (68.1%) than among Finnish-born patients (73.6%). After controlling for sociodemographic background and factors related to the type of disorder and treatment, migrants were more likely to discontinue medication (adjusted hazard ratio 1.28, 95% confidence interval 1.08-1.52). The risk of discontinuation was highest among migrants from North Africa and the Middle East and Sub-Saharan Africa and among recent migrants. Non-use of antipsychotic treatment before being diagnosed with psychosis, involuntary hospitalization and diagnosis other than schizophrenia were associated with earlier discontinuation both among migrants and non-migrants. CONCLUSIONS: Migrants with a psychotic disorder are less likely to continue antipsychotic treatment than non-migrants. The needs of migrant patients have to be addressed to improve adherence.

Use of benzodiazepine and related drugs in migrants and Finnish-born persons: a nationwide register-based study.

AIMS: Benzodiazepines and related drugs (BZDR) are often used longer than generally recommended. The aim is to study patterns of use among migrant and Finnish-born users of BZDR, and to identify factors that are associated with long-term use and BZDR polytherapy. METHODS: This register-based study includes a nationwide sample of migrants (n=8729) and their Finnish-born controls (n=11 388) who had purchased BZDR in 2011-2014, but not in 2009-2010. Information on drug purchases was obtained from the National Prescription Register and the duration of drug use was estimated using PRE2DUP method. The main outcomes were long-term use of BZDR, polytherapy and time until discontinuation of BZDR use. Sociodemographic variables and information on preceding psychiatric diagnoses were included as covariates. Logistic and Cox regression analyses were the statistical methods used. RESULTS: Only migrants from Sub-Saharan Africa were more likely to discontinue the medication once initiated than Finnish-born users. Migrants were significantly less likely to be long-term users (adjusted odds ratio 0.79, 95% CI 0.70-0.89) or polytherapy users (aOR 0.90, 95% CI 0.84-0.97) of BZDR compared with Finnish-born participants. CONCLUSIONS: Migrants had less long-term and concomitant use of several BZDR than Finnish-born participants. The pattern of use is more optimal among migrants, but it may also reflect poorer access to mental health treatment.

Fostering trust and understanding in social and healthcare services with migrant-origin parents: qualitative focus-group interviews of foreign-born mothers living in Finland.

Migrant-origin families may have a pronounced need for psychosocial support and healthcare services, but they face barriers in using services. To ensure the timely use of services, it is important that families understand how service systems work and trust care providers. Thirty-two migrant-origin mothers living in Finland participated in five focus-group interviews and shared their wishes for social and healthcare professionals on how trust and understanding can be increased. The data were analyzed with Qualitative Content Analysis. We identified six main themes related to the use of services and professionals' behavior. These were the need for professionals to justify and explain questions, to meet each family as individuals, the importance of non-verbal communication, the need to talk about racism and discrimination, the importance of cultural sensitivity in services, and a discussion of positive aspects of life after migration and children`s strengths. To foster trust and mutual understanding in social and healthcare services, professionals should be aware of potential cultural differences in family life, while avoiding pre-conceived ideas. Misunderstandings can rise from language barriers and unclear or intimidating questions. It is important that professionals explain what they do and justify why they might inquire about a family's personal matters. Working with interpreters is necessary when professionals and parents do not share a common fluent language. Professionals should also pay attention to their non-verbal communication and to being friendly. Finally, it is important to show interest in families' experienced hardships such as racism as well as their strengths.

Purchases of psychotropic drugs among the migrant population in Finland: a nationwide register-based cohort study.

BACKGROUND: Migrant populations may have different mental health service needs when compared with native populations. One indicator of service use is the use of psychotropic medication. The aim of this study was to compare the purchases of psychotropic drugs among different migrant populations with the native population in Finland. METHODS: Foreign-born participants (n = 184 805) and their Finnish-born controls (n = 185 183) were identified from the Finnish Central Population Register. Information on their purchases of psychotropic drugs in 2011-15 was collected from the National Prescription Register. A washout period of 2009-10 was used to define incident purchases. Cox regression analysis was the statistical method used. RESULTS: At least one incident purchase of a psychotropic drug was identified for 11.1% of migrant women, 11.4% of Finnish-born women, 8.7% of migrant men and 9.8% of Finnish-born men. When controlled for age, sex, marital status, socioeconomic status and social assistance, migrants were less likely to purchase psychotropic drugs (adjusted hazard ratio 0.96, 95% confidence interval 0.93-0.98), but there was variation between different drug categories. Recent migrants and migrants from Asia and Sub-Saharan Africa were least likely to purchase drugs. Migrants from Nordic countries and other Western countries most closely resembled the Finnish-born controls. CONCLUSIONS: Recent migrants in Finland appear to use fewer psychotropic drugs than native Finns. It is important to analyze the reasons for this pattern, as they may indicate delays in access to care or benefits. The heterogeneity of migrant populations must also be considered when developing services to better address their needs.

Immigrants' mental health service use compared to that of native Finns: a register study.

PURPOSE: Many aspects related to migration might predispose immigrants to mental health problems. Yet immigrants have been shown to underuse mental health services. The aim of this study was to compare the intensity of psychiatric care, as an indicator of treatment adequacy, between natives and immigrants living in Finland. METHODS: We used nationwide register data that included all the immigrants living in Finland at the end of 2010 (n = 185,605) and their matched controls. Only those who had used mental health services were included in the analyses (n = 14,285). We used multinomial logistic regression to predict the categorized treatment intensity by immigrant status, region and country of origin, length of residence, and other background variables. RESULTS: Immigrants used mental health services less than Finnish controls and with lower intensity. The length of residence in Finland increased the probability of higher treatment intensity. Immigrants from Eastern Europe, sub-Saharan Africa, the Middle East, and Northern Africa were at the highest risk of receiving low-intensity treatment. CONCLUSIONS: Some immigrant groups seem to persistently receive less psychiatric treatment than Finnish-born controls. Identification of these groups is important and future research is needed to determine the mechanisms behind these patterns.

Use of health services among international migrant children - a systematic review.

BACKGROUND: Migrant children have specific health needs, and may face difficulties in accessing health care, but not enough is known about their health service use. This study aims to describe patterns of use of health services of international migrant children and differences to respective native populations. METHODS: Electronic databases PubMed and Web of Science, references of identified publications, and websites of relevant international agencies were searched. We included observational studies published between 2006 and 2016 that reported use of formal health services by migrant children (0-18 years), including first and second generation migrants. Data on study characteristics, study theme, main outcome and study quality were extracted. RESULTS: One hundred seven full texts were included in the review. Of the studies that reported comparable outcomes, half (50%) indicated less use of healthcare by migrants compared with non-migrants; 25% reported no difference, 18% reported greater use, and 7% did not report this outcome. There was variation by theme, so that the proportion of conclusions "less use" was most common in the categories "general access to care", "primary care" and "oral health", whereas in the use of emergency rooms or hospitalisations, the most common conclusion was "greater use". CONCLUSIONS: Migrant children appear to use different types of healthcare services less than native populations, with the exception of emergency and hospital services. SYSTEMATIC REVIEW REGISTRATION: PROSPERO systematic review registration number: CRD42016039876 .

Social risk factors for speech, scholastic and coordination disorders: a nationwide register-based study.

BACKGROUND: Broadly defined learning and coordination disorders (LCDs) are common in the population and have previously been associated with familial social risk factors and male sex. However, comprehensive nationwide studies of these risk factors in LCD subgroups are lacking. Our objective was to assess different LCDs in relation to sex and maternal education, marital status and socioeconomic status based on occupation. METHODS: We conducted a nationwide register-based study. The following diagnoses were identified from the Finnish Hospital Discharge Register (FHDR) according to the ICD-10 (n = 28,192): speech disorders (F80), scholastic disorders (F81), motor and coordination disorders (F82) and mixed developmental disorder (F83). To study cumulative incidence and male: female ratios of service use of LCDs, we used a cohort design among all Finnish children born singleton 1996-2007 (n = 690,654); to study social risk factors, we used a nested case-control design with extensive register data on both cases and matched controls (n = 106,616). RESULTS: The cumulative incidence was 4.7% for any LCD by age 15 and the changes in cumulative incidence over time were minor. The male: female ratios were 2.2-3.0 across LCD subgroups. Learning and coordination disorders were more common in households with lower maternal education, socioeconomic status based on occupation and among children with single mothers at the time of birth; the odds ratios (OR) for any LCD were 1.2-1.9 across risk factors. The odds for LCD diagnosis increased linearly with the number of social risk factors, except for coordination disorder. The effect size of three risk factors was highest in the group with mixed or multiple LCDs; OR 3.76 (95% CI 3.31-4.28). CONCLUSIONS: Multiple social risk factors increase the odds for multiple, more comprehensive learning difficulties. The findings have implications for service planning, as early identification and interventions of learning and coordination disorders might reduce related long-term social adversities.

Finnish-born children of immigrants are more likely to be diagnosed with developmental disorders related to speech and language, academic skills and coordination.

AIM: We examined the association between having at least one parent born abroad and being diagnosed with a developmental disorder related to speech and language, academic skills or coordination. METHODS: This nested case-control study was based on Finnish population records for 1996-2007. Cases from the Finnish Hospital Discharge Register were diagnosed with developmental disorders of speech and language, academic skills and coordination by the end of 2012. We identified 28 192 cases and 106 616 matched controls. RESULTS: Children were more likely to be diagnosed with developmental disorders if they had an immigrant mother than children with two Finnish-born parents, with an adjusted odds ratio (aOR) of 1.3 and 95% confidence interval (95% CI) of 1.2-1.4, an immigrant father (aOR 1.2, 95% CI 1.1-1.3) or two immigrant parents (aOR 1.5, 95% CI 1.3-1.6). The level of development of the parental country of origin was not associated with receiving a diagnosis. CONCLUSION: Children of immigrant parents were more likely to be diagnosed with developmental disorders and the association was strongest with regard to speech and language disorders. There were similar adjusted odds ratios for mothers, fathers and both parents. The development level of the country of origin was irrelevant.

Mortality and causes of death among the migrant population of Finland in 2011-13.

Background: Lower mortality among migrants than in the general population has been found in many, but not in all, previous studies. The mortality of migrants has not been studied in Finland, which has a relatively small and recent migrant population. Methods: People who were born abroad and whose mother tongue is not Finnish were identified from the Finnish Central Population Register (n = 185 605). A Finnish-born control matched by age, sex and place of residence was identified for each case (n = 185 605). Information about deaths was collected from the Finnish Causes of Death Register. Cox proportional hazards model was used for assessing the association between migrant status and death in 2011­13. Results: The mortality risk was found to be significantly lower for migrants than for Finnish controls (adjusted hazard ratio 0.77, 95% CI 0.72­0.84), both for migrant men (aHR 0.80, 95% CI 0.73­0.89) and women (aHR 0.78, 95% CI 0.70­0.88). The difference was statistically significant only among people who were not married and among people who were not in employment. There was variation by country of birth, but no migrant group had higher mortality than Finnish controls. No differences in mortality were found by duration of residence in Finland. The higher mortality of Finnish controls was largely explained by alcohol-related conditions and external causes of death. Conclusions: The mortality risk of migrants is lower than of people who were born in Finland. Possible explanations include selection and differences in substance use and other health behaviour.

Incidence and prevalence of mental disorders among immigrants and native Finns: a register-based study.

PURPOSE: Migrants appear to have a higher risk of mental disorders, but findings vary across country settings and migrant groups. We aimed to assess incidence and prevalence of mental disorders among immigrants and Finnish-born controls in a register-based cohort study. METHODS: A register-based cohort study of 184.806 immigrants and 185.184 Finnish-born controls (1.412.117 person-years) was conducted. Information on mental disorders according to ICD-10 was retrieved from the Hospital Discharge Register, which covers all public health care use. RESULTS: The incidence of any mental disorder was lower among male (adjusted HR 0.82, 95% CI 0.77-0.87) and female (aHR 0.76, 95% CI 0.72-0.81) immigrants, being lowest among Asian and highest among North African and Middle Eastern immigrants. The incidence of bipolar, depressive and alcohol use disorders was lower among immigrants. Incidence of psychotic disorders was lower among female and not higher among male immigrants, compared with native Finns. Incidence of PTSD was higher among male immigrants (aHR 4.88, 95% CI 3.38-7.05). CONCLUSIONS: The risk of mental disorders varies significantly across migrant groups and disorders and is generally lower among immigrants than native Finns.

Association between immigrant background and ADHD: a nationwide population-based case-control study.

BACKGROUND: Information about psychiatric disorders among those with immigrant parents is important for early detection and service development. The aim of this study is to examine the association between parental immigration and the diagnosis of attention-deficit hyperactivity disorder (ADHD) in offspring in Finland. METHODS: This matched case-control study was based on a national birth cohort. The sample included all singletons who were born in Finland in 1991-2005 and diagnosed with ADHD by the year 2011 (n = 10,409) and their matched controls (n = 39,124). Nationwide registers were used to identify participants and to gather information on the parents' country of birth and native language. Conditional logistic regression analyses were conducted using maternal and paternal migration status and region of birth as well as time since maternal migration as exposure factors. RESULTS: The likelihood of being diagnosed with ADHD was significantly increased among children of two immigrant parents [adjusted odds ratio (aOR) 4.7, 95% CI 3.4-6.6] and children of an immigrant father (aOR 1.9, 95% CI 1.6-2.2). The likelihood of receiving an ADHD diagnosis was equal among children whose mother was a recent immigrant when she gave birth and those whose mother had stayed in Finland at least for a year before birth. The association between parental migration and ADHD diagnosis was strongest among fathers born in sub-Saharan Africa or Latin America and among mothers born in sub-Saharan Africa or North Africa and Middle East. Children, whose parents were born in countries with low Human Development Index (HDI), were more often diagnosed with ADHD. CONCLUSIONS: The increased likelihood of ADHD diagnosis among children of immigrants indicates increased exposure to environmental risk factors, differences in the use of health services, or challenges in diagnosing immigrants' children.

Parental migration and Asperger's syndrome.

Parental immigration has been suggested as a possible risk factor for autism spectrum disorders (ASD), but findings have been inconsistent. Very few studies have focused specifically on Asperger's syndrome. The aim of this study was to examine the association between maternal and paternal immigration and the diagnosis of Asperger's syndrome in offspring. The study was a nested case-control study based on a national birth cohort in Finland. Children born in 1987-2005 and diagnosed with Asperger's syndrome by the year 2007 were identified from the Finnish Hospital Discharge Register (N = 1,783). Four matched controls for each case were selected from the Finnish Medical Birth Register (N = 7,106). Information on maternal and paternal country of birth and mother tongue was collected from the Finnish Central Population Register. The study showed that children whose parents are both immigrants have a significantly lower likelihood of being diagnosed with Asperger's syndrome than those with two Finnish parents [adjusted odds ratio (aOR) 0.2, 95 % confidence interval (CI) 0.1-0.4]. No significant associations were found between having only one immigrant parent and the diagnosis of Asperger's syndrome. A regional analysis showed a significantly decreased likelihood of the diagnosis of Asperger's syndrome in children whose mother (aOR 0.1, 95 % CI 0.01-0.5) or father (aOR 0.2, 95 % CI 0.05-0.5) was born in Sub-Saharan Africa. The findings may help in identifying risk factors for different ASD subtypes. On the other hand, they might reflect service use of immigrant families in Finland.

Maternal socio-economic status based on occupation and autism spectrum disorders: a national case-control study.

BACKGROUND: The association between parental socio-economic status (SES) and autism spectrum disorders (ASD) has been studied in several countries, but the results have been contradictory. AIMS: The aim of this study was to examine the association between maternal SES and subtypes of ASD in Finland. METHODS: A national case-control study was conducted. Children born in 1991-2005 and diagnosed with ASD by the year 2007 were identified from the Finnish Hospital Discharge Register (FHDR). Their matched controls were selected from the Finnish Medical Birth Register (FMBR). There were 3468 cases and 13,868 controls. The information on maternal SES was collected from the FMBR and categorized into upper white-collar workers (referent), lower white-collar workers, blue-collar workers and "others", consisting of students, housewives and other groups with unknown SES. The statistical test used was conditional logistic regression. RESULTS: The likelihood of ASD was increased among offspring of mothers who belong to the group "others" (adjusted OR = 1.2, 95% CI 1.009-1.3). The likelihood of Asperger's syndrome was decreased among offspring of lower white-collar workers (adjusted OR = 0.8, 95% CI 0.6-0.9) and blue-collar workers (adjusted OR = 0.6, 95% CI 0.5-0.7). The likelihood of pervasive developmental disorder not otherwise specified (PDD-NOS) was increased among offspring of blue-collar workers (adjusted OR = 1.5, 1.2-1.9) and "others" (adjusted OR = 1.3, 1.1-1.7). No association was found between maternal SES and childhood autism. CONCLUSIONS: The association between maternal SES and ASD differs by ASD subtype. Socio-economic groups might differ from each other by risk factors for ASD subtypes or by their service use.

Parental age and the risk of bipolar disorders.

OBJECTIVES: 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. METHODS: This nested case-control study identified 1,861 cases of individuals with BPD born in Finland during 1983-1998 and diagnosed by the end of 2008, and 3,643 sex- and date of birth-matched controls from nationwide population-based registers. Conditional logistic regression was used to examine the association adjusting for potential confounding due to age of the other parent, parental psychiatric history, educational level, and place of birth. RESULTS: A U-shaped association of unadjusted odds ratios (ORs) for BPD risk was seen in different paternal age categories, with the odds increasing at both ends of the age spectrum. In the adjusted analyses, offspring of fathers aged ≥ 50 years had a 2.8-fold increased odds [OR = 2.84, 95% confidence interval (CI): 1.32-6.12] of BPD as compared to those with fathers aged 30-34 years. The odds were increased 1.3-fold (OR = 1.35, CI: 1.06-1.72) in fathers aged 20-24 years. No significant association was found between maternal age and BPD in the adjusted analyses. Age difference between parents was not associated with BPD. CONCLUSIONS: The increased risk of BPD in offspring of the youngest and oldest fathers in the study suggests the involvement of different biological and psychosocial factors at the two ends of the paternal age spectrum. These findings may be significant in the context of advancing parental age in recent times.

Variation by diagnostic subtype in risk for autism spectrum disorders associated with maternal parity among Finnish births.

BACKGROUND: Associations between maternal parity and outcomes in offspring may provide evidence for involvement of prenatal exposures. The objective of this study was to determine whether risk for autism spectrum disorders (ASD) is associated with maternal parity. METHODS: Diagnoses of childhood autism, Asperger syndrome, and pervasive developmental disorder, not otherwise specified (PDD-NOS) were examined separately and as a group. The study was conducted in the Finnish Prenatal Study of Autism, which is based in a national birth cohort. Children born in Finland in 1987-2005 and diagnosed with ASD by 2007 were identified through the Finnish Hospital Discharge Register. Four matched controls were selected for each case using the Finnish Medical Birth Register. The association between parity and each ASD was determined using conditional logistic regression and adjusted for number of children in the sibship and other potential confounders. RESULTS: ASDs combined showed a pattern of decreasing risk with increasing parity (odds ratio OR for fourth or greater vs. first-born children, 0.43 [95% confidence interval (CI): 0.35, 0.51]). For childhood autism, an adjusted OR of 1.51 [95% CI 1.27, 1.81] was observed for second vs. first-born children. Associations for Asperger syndrome and PDD-NOS were consistent with those for all ASDs. CONCLUSIONS: Differences in patterns of association between maternal parity and ASD subtypes may indicate varying contributions of specific environmental factors to risk; however, differences in diagnosis or in treatment seeking for childhood behavioural problems cannot be ruled out, particularly for higher functioning cases.

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

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.

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, mother's socio-economic and psychiatric status, and infant's 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 Asperger's syndrome.

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

BACKGROUND: Studying 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. METHODS: The 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. RESULTS: Compared 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. CONCLUSIONS: In 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.

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 infant's 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.