Severity and persistence of asthma and mental health: a birth cohort study.

BACKGROUND: The goal of the current study was to investigate asthma and mental health among youth in the community, and to consider the role of asthma severity and persistence in this link. Method Data were drawn from the Raine Study, a population-based birth cohort study in Western Australia. Logistic regression models and generalized estimating equations were used to examine the relationship between asthma at age 5 years and the range of internalizing and externalizing mental health problems at ages 5-17 years. Analyses were stratified by asthma severity and persistence, and adjusted for a range of potential confounders. RESULTS: More severe and persistent asthma at age 5 was associated with significantly increased odds of affective, anxiety, somatic, oppositional defiant and conduct problems at ages 5-17. Mild asthma and remitted asthma were not associated with heightened vulnerability to mental disorders. CONCLUSIONS: Our results suggest that youth with symptomatic asthma are more likely to suffer from a wide range of mental health problems, and that the likelihood of mental health problems appears to increase as a function of asthma severity. Youth with poorly controlled and/or more severe and persistent asthma may be considered a vulnerable group who might benefit from mental health screening in clinical, school and community settings.

Pre-pregnancy maternal overweight and obesity increase the risk for affective disorders in offspring.

Maternal pre-pregnancy obesity has been linked with an increased risk for negative emotionality and inattentiveness in offspring in early childhood. The aim of this study was to examine the association between maternal pre-pregnancy body mass index (BMI) and the development of affective problems (dysthymic disorder, major depressive disorder) throughout childhood and adolescence. In the Western Australian Pregnancy Cohort (Raine) Study, 2900 women provided data on their pre-pregnancy weight, and height measurements were taken at 18 weeks of gestation. BMI was calculated and categorized using standardized methods. Live-born children (n = 2868) were followed up at ages 5, 8, 10, 14 and 17 years using the Diagnostic and Statistical Manual of Mental Disorders-oriented scales of the Child Behavior Checklist (CBCL/4-18). Longitudinal models were applied to assess the relationships between maternal pre-pregnancy BMI and affective problems from age 5 through 17. There was a higher risk of affective problems between the ages of 5 and 17 years among children of women who were overweight and obese compared with the offspring of women in the healthy pre-pregnancy weight range (BMI 18.5-24.99) after adjustment for confounders, including paternal BMI. Maternal pre-pregnancy overweight and obesity may be implicated in the development of affective problems, including depression, in their offspring later in life.

Analysis of dyslexia candidate genes in the Raine cohort representing the general Australian population.

Several genes have been suggested as dyslexia candidates. Some of these candidate genes have been recently shown to be associated with literacy measures in sample cohorts derived from the general population. Here, we have conducted an association study in a novel sample derived from the Australian population (the Raine cohort) to further investigate the role of dyslexia candidate genes. We analysed markers, previously reported to be associated with dyslexia, located within the MRPL19/C2ORF3, KIAA0319, DCDC2 and DYX1C1 genes in a sample of 520 individuals and tested them for association with reading and spelling measures. Association signals were detected for several single nucleotide polymorphisms (SNPs) within DYX1C1 with both the reading and spelling tests. The high linkage disequilibrium (LD) we observed across the DYX1C1 gene suggests that the association signal might not be refined by further genetic mapping.

Low-moderate prenatal alcohol exposure and risk to child behavioural development: a prospective cohort study.

OBJECTIVE: To examine the association of fetal alcohol exposure during pregnancy with child and adolescent behavioural development. DESIGN: The Western Australian Pregnancy Cohort (Raine) Study recruited 2900 pregnancies (1989-91) and the 14-year follow up was conducted between 2003 and 2006. SETTING: Tertiary obstetric hospital in Perth, Western Australia. POPULATION: The women in the study provided data at 18 and 34 weeks of gestation on weekly alcohol intake: no drinking, occasional drinking (up to one standard drink per week), light drinking (2-6 standard drinks per week), moderate drinking (7-10 standard drinks per week), and heavy drinking (11 or more standard drinks per week). Methods Longitudinal regression models were used to analyse the effect of prenatal alcohol exposure on Child Behaviour Checklist (CBCL) scores over 14 years, assessed by continuous z-scores and clinical cutoff points, after adjusting for confounders. MAIN OUTCOME MEASURE: Their children were followed up at ages 2, 5, 8, 10 and 14 years. The CBCL was used to measure child behaviour. RESULTS: Light drinking and moderate drinking in the first 3 months of pregnancy were associated with child CBCL z-scores indicative of positive behaviour over 14 years after adjusting for maternal and sociodemographic characteristics. These changes in z-score indicated a clinically meaningful reduction in total, internalising and externalising behavioural problems across the 14 years of follow up. CONCLUSIONS: Our findings do not implicate light-moderate consumption of alcohol in pregnancy as a risk factor in the epidemiology of child behavioural problems.

Trends in mode of delivery during 1984-2003: can they be explained by pregnancy and delivery complications?

OBJECTIVES: To describe trends in mode of delivery, to identify significant factors which affected mode of delivery, and to describe how these factors and their impact have changed over time. DESIGN: Total population birth cohort. SETTING: Western Australia 1984-2003. PARTICIPANTS: The analysis was restricted to all singleton infants delivered at 37-42 weeks of gestation with a cephalic presentation (n = 432,327). METHODS: Logistic regression analyses were undertaken to estimate significant independent risk factors separately for elective and emergency caesarean sections compared with vaginal delivery (spontaneous and instrumental), adjusting for potential confounding variables. MAIN OUTCOME MEASURES: Trends in mode of delivery, demographic factors, and pregnancy and delivery complications. Estimated likelihood of elective caesarean section compared with vaginal delivery and emergency caesarean section compared with vaginal delivery. RESULTS: Between 1984-88 and 1999-2003, the likelihood of women having an elective caesarean section increased by a factor of 2.35 times (95% CI 2.28-2.42) and the likelihood of an emergency caesarean section increased 1.89 times (95% CI 1.83-1.96). These caesarean section rate increases remained even after adjustment for their strong associations with many sociodemographic factors, obstetric risk factors, and obstetric complications. Rates of caesarean section were higher in older mothers, especially those older than 40 years of age (elective caesarean section, OR 5.42 [95% CI 4.88-6.01]; emergency caesarean section, OR 2.67 [95% CI 2.39-2.97]), and in nulliparous women (elective caesarean section, OR 1.54 [95% CI 1.47-1.61]; emergency caesarean section, OR 3.61 [95% CI 3.47-3.76]). CONCLUSIONS: Our data show significant changes in mode of delivery in Western Australia from 1984-2003, with an increasing trend in both elective and emergency caesarean section rates that do not appear to be explained by increased risk or indication.

Perinatal and childhood origins of cardiovascular disease.

BACKGROUND: Features of the metabolic syndrome comprise a major risk for cardiovascular disease and will increase in prevalence with rising childhood obesity. We sought to identify early life influences on development of obesity, hypertension and dyslipidemia in children. METHODS AND RESULTS: Cluster analysis was used on a subset of a longitudinal Australian birth cohort who had blood samples at age 8 (n=406). A quarter of these 8-year-olds fell into a cluster with higher body mass index, blood pressure (BP), more adverse lipid profile and a trend to higher serum glucose resembling adult metabolic syndrome. There was a U-shaped relationship between percentage of expected birth weight (PEBW) and likelihood of being in the high-risk cluster. The high-risk cluster had elevated BP and weight as early as 1 and 3 years old. Increased likelihood of the high-risk cluster group occurred with greatest weight gain from 1 to 8 years old (odds ratio (OR)=1.4, 95% confidence interval (CI)=1.3-1.5/kg) and if mothers smoked during pregnancy (OR=1.82, CI=1.05-3.2). Risk was lower if children were breast fed for >/=4 months (OR=0.6, 95% CI=0.37-0.97). Newborns in the upper two quintiles for PEBW born to mothers who smoked throughout pregnancy were at greatest risk (OR=14.0, 95% CI=3.8-51.1) compared to the nadir PEBW quintile of non-smokers. CONCLUSION: A U-shaped relationship between birth weight and several components of the metabolic syndrome was confirmed in a contemporary, well-nourished Western population of full-term newborns, but post-natal weight gain was the dominant factor associated with the high-risk cluster. There was a prominence of higher as well as lowest birth weights in those at risk. Future health programs should focus on both pre- and post-natal factors (reducing excess childhood weight gain and smoking during pregnancy), and possibly the greatest benefits may arise from targeting the heaviest, as well as lightest newborns, especially with a history of maternal smoking during pregnancy.

Health of caregivers in child care.

BACKGROUND: Child care workers play an important role in caring for children attending child care yet there is little research regarding their health. METHODS: The study consisted of focus groups with child care workers and a survey, conducted as part of a larger study known as the Healthy Child Care Study, which focused on children. The study investigated carers working in formal child care [long day care (LDC) and family day care (FDC)]. RESULTS: Questionnaires to caregivers in centres showed that 86% had taken sick leave in the previous year and 75% of staff had taken leave for infectious illness. Carers in FDC reported that 24% had taken sick leave in the previous year and 12% of carers had taken leave for infectious illness. Of responding caregivers from centres, 22% were cigarette smokers while in FDC homes, 8% of carers smoked. In focus groups, carers reported that their major areas of health concern were stress, infectious illness and physical trauma such as lifting injuries. CONCLUSIONS: Child care workers in LDC took more sick leave than those in FDC but this is not necessarily due to more illness. Child care workers are a diverse and important group that require further research.

Interpretation of recent sudden infant death syndrome rates in Western Australia.

The diagnosis of sudden infant death syndrome (SIDS) has undergone several changes in definition since first being recognised as a cause of death. Linked total population data from Western Australia enable investigations to determine changes in classifications of mortality for the infants of Aboriginal and non-Aboriginal mothers (Aboriginal and Torres Strait Islander people are referred to throughout this report as 'Aboriginal'). Data for recent years show a shift away from a classification of 'SIDS' towards a classification of 'unascertainable', particularly for Aboriginal infants. This has implications for the accurate translation of data into policy and practice.

Predictors of body mass index and associations with cardiovascular risk factors in Australian children: a prospective cohort study.

OBJECTIVE: To examine predictors of body mass index (BMI) at the age of 8 y in a prospective study of Australian children. DESIGN: Longitudinal survey of a cohort of Australian children followed from the 16th week of gestation to 8 y. SUBJECTS: In total, 741 boys and 689 girls who attended the survey as 8 y olds. MEASUREMENTS: Weight and height, blood pressure measured by automated oscillometry, fasting blood lipids and glucose. Questionnaire assessment of activity and diet. RESULTS: Proportions of overweight including obesity in boys and girls were, respectively, 22 and 25% at 1 y, 14 and 14% at 3 y, 13 and 18% at 5 y and 15 and 20% at 8 y. At the age of 1, 3, 6 and 8 y, children with overweight including obesity showed significantly more adverse cardiovascular risk factors. Blood pressure (BP) was significantly higher by 2/3 mmHg (systolic/diastolic) at 1 y, 3/2 mmHg at 3 y, 4/2 mmHg at 5 y and 6/2 mmHg at 8 y; HDL was significantly lower (P=0.002) by 8% and triglycerides were significantly higher by 27% (P<0.001). In multivariate regression, BMI at the age of 8 y was significantly predicted positively by birth weight, mother's BMI and hours spent in watching television at the time of the survey of 6 y olds. Mothers being ex-smokers or non smokers and children being 'slightly active' and 'active' negatively predicted BMI in 8 y olds. In a subset of 298 children with information about fathers, paternal BMI was an additional independent predictor. Maternal or paternal overweight including obesity each independently increased risk of overweight including obesity at the age of 8 y three-fold. A food factor with consumption of cereals and breads as the major components derived from a Food Frequency Questionnaire in a subset of 340 children was also an independent negative predictor of BMI in multivariate models. CONCLUSION: The increasing rate of overweight including obesity, particularly in girls, is associated with an increase in cardiovascular risk factors very early in life. Improvement of health-related behaviours within the family and a focus on promotion of activity in children should be priorities in achieving weight control.

Absence from childcare for respiratory illness.

BACKGROUND: This population-based study investigated prospectively collected absence for respiratory illness data in two types of formal childcare (centre day care and family day care) in Perth, Western Australia, and factors associated with such absence. METHODS: All centres (n = 11) and 95% of family day care caregivers (n = 130) selected at random from licensing lists agreed to participate. Demographic details were obtained from a parental questionnaire and absences were recorded prospectively. Characteristics of the child and family were described using univariate odds ratios (OR) with 95% confidence intervals (CI). Multivariable analysis including generalized estimating equations was used to investigate having at least one absence for respiratory illness, having two or more absences, and having six or more absences. RESULTS: No statistically significant difference between care types for having had at least one absence episode for respiratory illness (OR 1.37, 95% CI 0.92-2.04) was found. Children who attended care for more days per week (OR 1.40, 95% CI 1.26-1.56) and those in the study for more weeks (OR 1.03, 95% CI 1.01-1.05) were more likely to be absent for respiratory illness. Those children in care for a greater number of hours per day were less likely to be absent (OR 0.88, 95% CI 0.80-0.97). Family history of bronchitis was also associated with absence for respiratory illness (OR 1.86, 95% CI 1.32-2.63). CONCLUSIONS: Statistically significant factors which had an impact on absence for respiratory illness were primarily those relating to the time spent in childcare and to family history of bronchitis.

Breast feeding and respiratory morbidity in infancy: a birth cohort study.

AIM: To examine the relation between the duration of breast feeding and morbidity as a result of respiratory illness and infection in the first year of life. METHODS: Prospective birth cohort study of 2602 live born children ascertained through antenatal clinics at the major tertiary obstetric hospital in Perth, Western Australia. Main outcome measures were hospital, doctor, or clinic visits, and hospital admissions for respiratory illness and infection in the first year of life. Main exposure measures were the duration of predominant breast feeding (defined as the age other milk was introduced) and partial (any) breast feeding (defined as the age breast feeding was stopped). Main confounders were gender, gestational age less than 37 weeks, smoking in pregnancy, older siblings, maternal education, and maternal age. RESULTS: Hospital, doctor, or clinic visits for four or more upper respiratory tract infections were significantly greater if predominant breast feeding was stopped before 2 months or partial breast feeding was stopped before 6 months. Predominant breast feeding for less than six months was associated with an increased risk for two or more hospital, doctor, or clinic visits and hospital admission for wheezing lower respiratory illness. Breast feeding for less than eight months was associated with a significantly increased risk for two or more hospital, doctor, or clinic visits or hospital admissions because of wheezing lower respiratory illnesses. CONCLUSIONS: Predominant breast feeding for at least six months and partial breast feeding for up to one year may reduce the prevalence and subsequent morbidity of respiratory illness and infection in infancy.

Prenatal ultrasound biometry related to subsequent blood pressure in childhood.

STUDY OBJECTIVE: To relate measures of fetal growth/size other than birth weight with subsequent blood pressure measured on the same individuals within the context of the "fetal origins of adult disease". DESIGN: A prospective cohort study in which measurements of fetal dimensions obtained by serial ultrasound imaging between 18 and 38 weeks gestation were analysed with reference to systolic blood pressure measurements on the offspring at age 6 years. SETTING: Perth, Western Australia. PARTICIPANTS: A subgroup of 707 eligible mother-fetus pairs from a cohort of 2876 pregnant women and their offspring. The number of mother-fetus pairs varied at each gestational age and by measurement of fetal dimension. Subsequent blood pressure recordings were obtained on approximately 300 of the offspring at age 6 years. MAIN RESULTS: The findings confirmed the inverse association between birth weight and systolic blood pressure at age 6. There was, also, an inverse relation between fetal femur length and systolic blood pressure at age 6, adjusted for current height. Furthermore, an inverse association was demonstrated between a statistically derived measure of fetal growth (conditional z score) between 18 and 38 weeks gestation and later systolic blood pressure at age 6. The effect sizes for all three relations were in the order of 1-2 mm Hg per standard deviation change. CONCLUSION: The mechanisms underpinning the "fetal origins" hypothesis may be operative early in pregnancy and may be reflected in the length of the fetal femur in early to mid-pregnancy.

A prospective study of absence for illness and injury in childcare children.

OBJECTIVES: This population-based study investigated prospectively collected absence episodes to describe patterns and rates of absences for illness and other reasons in two types of formal childcare. DESIGN: Centre day care and family day care homes were selected at random from licensing lists. All centres (n = 11) and 95% of family day care caregivers (n = 130) agreed to participate. The results are based on absence information from carers and on questionnaires to the parents of participating children (n = 846). RESULTS: The major reason for absence was respiratory illness with 48% of all children absent at least once during the year with some form of respiratory illness. Although the absence rate for children in centre care was higher than that in family care (3.34 episodes per 52 child-weeks compared with 2.41), the difference was not statistically significant. CONCLUSION: Investigating patterns of absences from childcare allows a better understanding of needs in childcare. The major reason for absence for illness was respiratory illness.

Life expectancy among people with cerebral palsy in Western Australia.

This report describes trends, predictors, and causes of mortality in persons with cerebral palsy (CP) using individuals identified by the Western Australian Cerebral Palsy Register and born between 1958 and 1994. Two thousand and fourteen people were identified (1154 males, 860 females), of whom 225 had died by 1 June 1997. Using date-of-death data, crude and standardized mortality rates were estimated and predictors of mortality sought using survival analysis stratified by decade of birth, description of impairments, and demographic and perinatal variables. For those born after 1967, the cause of death profile was examined over time. Mortality exceeded 1% per annum in the first 5 years and declined to age 15 years after which it remained steady at about 0.35% for the next 20 years. The strongest single predictor was intellectual disability, but all forms of disability contributed to decreased life expectancy. Half of those with IQ/DQ score <20 survived to adulthood, increasing to 76% with IQ/DQ score 20-34, and exceeding 92% for higher scores. Severe motor impairment primarily increased the risk of early mortality. Despite there being 72 persons aged from 25 to 41 years with severe motor impairment in our data set, none had died after the age of 25 years. Infants born after more than 32 weeks' gestation were at significantly higher risk of mortality than very preterm infants, accounted for by their higher rates of intellectual disability. No improvements in survival of persons with CP were seen over the study period despite advances in medical care, improved community awareness, and the increasing proportion of very preterm births among people with CP. This may be the result of improved neonatal care enabling the survival of infants with increasingly severe disabilities.

Placental weight and placental ratio as predictors of later blood pressure in childhood.

OBJECTIVE: A significant inverse relationship between blood pressure and birth weight is firmly established. This association may be the result of fetal adaptations to an adverse intrauterine environment. Further markers of intrauterine growth include the weight of the placenta and the placental ratio (the ratio of placental weight to birth weight). A number of studies suggest that a decreased placental weight or an elevated placental ratio may be independent risk factors for subsequent high blood pressure. The overall evidence for this is, however, inconclusive. The purpose of the present study was to clearly define the relationships between placental weight, placental ratio and subsequent blood pressure during childhood. DESIGN: Prospective cohort study of 2507 singleton children, born at term during 1989-1992. Blood pressures were recorded at ages 1, 3 and 6 years, using a semi-automated oscillometric device. RESULTS: Inverse relationships existed between both systolic and diastolic blood pressure and placental weight, adjusted for current weight at ages 1, 3 and 6 years. The relationships between placental weight and systolic blood pressure were statistically significant at ages 1 and 3 years. There was no consistent relationship between placental weight and later blood pressure within birth weight categories. No clinically or statistically significant association was seen between the placental ratio and either systolic or diastolic blood pressures at any age. CONCLUSIONS: Birth weight, rather than placental weight or their ratio, is the early life factor most importantly related to subsequent blood pressure in childhood.

Parental attitudes to health of children in child-care centres and options when children are ill.

OBJECTIVE: To determine parental attitudes regarding the health of children attending child-care centres, to explore concerns when children who normally attend child care are ill, and to investigate options in these circumstances. METHODOLOGY: Focus groups conducted with parents whose children attended child-care centres. Ten focus groups were conducted. RESULTS: Many parents encountered difficulty when children who normally attend child care were ill and there was a lack of options for care. Parents were concerned about the spread of infections among children but considered that there were also many health and other advantages for their children in attending child care. Child-care centres were perceived as providing a valuable support role for families. CONCLUSIONS: Many parents lack adequate options for care when their children are ill. Parents' concerns regarding health in child care are important in policy decisions regarding the health of children in child care, and the development of alternative care services for children.

Why is the placenta being ignored?

The relationship between the frequency of published recommended indications for placental pathological examination and the frequency of requests for such examination in a population-based study of term newborn encephalopathy was examined. Only 11.2% of placentas among 276 case infants and 0.7% of placentas among 564 term control infants were examined. Using the criteria set out in a consensus statement by the American College of Pathologists, all 276 cases fulfilled multiple maternal, fetal and placental indications for placental examination. Furthermore 43.3% of control infants fulfilled at least one criterion. Of the 25 case placentas that underwent pathological review, 16 were reported as having no diagnostic abnormality Six cases (24%) showed clinically important findings: four had evidence of infection, one had multiple chorangiomata and one had thrombosis and rupture of the umbilical vein. Of the three remaining placentas, one showed funisitis, one showed minor lymphohistiocytic villitis and one was from monochorionic twins. To our knowledge there are no agreed Australian guidelines for when a placenta should be submitted for pathological examination. We suggest that until guidelines based on properly designed studies are developed it may be appropriate to store all placentas for at least 72 hours. If the infant develops neurological symptoms or requires unexpected admission to a neonatal intensive care unit then placental examination may reveal important aetiological diagnostic and prognostic information.

Adjustment for current weight and the relationship between birth weight and blood pressure in childhood.

OBJECTIVE: To determine the role of current weight in mediating the relationship between birth weight and blood pressure within the context of the 'fetal origins' hypothesis. DESIGN: Prospective cohort study of 2507 pregnant women and their singleton offspring, delivered live at term, in Perth, Western Australia between 1989 and 1992. The study commenced at 16 weeks gestation with serial weight and blood pressure measurements recorded through early childhood. RESULTS: Inverse associations were found between birth weight and systolic blood pressure at ages 1, 3 and 6. The effect of birth weight on systolic blood pressure at age 6 reached statistical significance and was increased fourfold in magnitude to -2.3 mmHg [95% confidence interval = (-3.3 to -1.3), P < 0.01] after adjustment for current weight. The interaction term for birth weight and current weight was not statistically significant. Including intermediate weights did not produce a statistically significantly better model but did increase the magnitude of the estimated regression coefficient of birth weight on blood pressure, and only the birth weight and current weight terms were significant CONCLUSIONS: Adjustment for current weight serves to highlight the relationship between birth weight and blood pressure in childhood. Nevertheless, birth weight, rather than birth weight adjusted for current weight, is still the relevant predictor of later blood pressure within the context of the 'fetal origins' hypothesis.

Maternal thyroid disease: a risk factor for newborn encephalopathy in term infants.

Two previously published studies of term newborn encephalopathy showed that maternal thyroid disease to be a risk factor. From these studies we identified 13 case and three control mothers with thyroid disease and investigated them further. The majority of affected case mothers had idiopathic or autoimmune hypothyroidism. Compared with control mothers, case mothers had fewer thyroid function tests in pregnancy, were more likely to remain on the same dose of medication throughout pregnancy and to have experienced other pregnancy complications. The association between maternal thyroid disease and encephalopathy may be the result of a series of different causal pathways, some of which are suggested by our data.