Perinatal and maternal risk factors for autism spectrum disorders in New South Wales, Australia.

BACKGROUND: This study was commenced in 1999 with the aim of examining risk factors for autism using established population-based data for comparison. METHODS: Cases were ascertained using active surveillance and compared with birth data. RESULTS: Four risk factors were found to be significantly associated with autism using binary logistic regression analysis; being male [adjusted odds ratio (OR) 4.7, 95% confidence interval (CI) 3.2-7.0], being born prematurely (adjusted OR 2.2, 95% CI 1.5-3.5), having maternal age >/=35 years (adjusted OR 1.7, 95% CI 1.2-2.4) and having a mother born outside Australia (adjusted OR 1.4, 95% CI 1.0-1.9). For analysis completed for pregnancies, rather than live births, multiple birth was also a significant risk factor for one or more children of the pregnancy to be affected by autism (adjusted OR 2.5, 95% CI 1.1-5.5). There was a statistically significant trend towards increasing risk with increasing risk factor 'dose' for gestational age (P = 0.019), multiple birth (P = 0.016) and maternal age (P < 0.001). For mother's country of birth the group with the highest risk were children of mother's born in south-east or north-east Asia. There was a non-significant trend towards a higher proportion of children with developmental disability having risk factors. CONCLUSION: Replication of risk factors from previous studies and a significant risk factor 'dose' effect add to growing evidence that maternal and perinatal factors are low magnitude risk factors for autism. The association between developmental disability and autism risk factors warrants further examination.

Description of HLA-DRB1*1371 allele, which has the 3' intron 1 sequence and HLA-DQB1 association normally seen with a DRB1*0301 allele.

Human leukocyte antigen (HLA) typing of a newly recruited, potential volunteer haematopoietic stem cell donor (ALSM4092AN) indicated the presence of a variant DRB1*13 allele, which has now been named DRB1*1371.

Childhood asthma diagnosis and use of asthma medication.

AIM: To determine the burden of asthma in children. METHODS: A cross sectional, randomised, computer assisted telephone survey of a community based sample of 2020 children aged 5-14 years in western Sydney (New South Wales) over a 20 day period from June 2000 to July 2000. RESULTS: Main outcome measures were carer reported history of asthma diagnosis, hospital presentation/admission for asthma, recent use of anti-asthma medications, and recent respiratory symptoms. Diagnosed asthma was reported in 31% (of whom 42% were diagnosed aged 2 years or under) and asthma medications used in the previous year by 21% of children. Factors significantly associated with a reported asthma diagnosis included: male gender (OR: 1.51), birth in Australia (OR: 1.64), living in an English speaking household (OR: 1.47), Aboriginality (OR: 2.32), possession of a health care card (OR: 1.28), previous pneumonia (OR: 2.4) or pertussis (OR: 2.0), and a recent episode of croup (OR: 1.9). Exposure to tobacco smoke and immunisation status were not significant. DISCUSSION: We confirm a high prevalence of asthma and medication use for asthma. The high proportion of children diagnosed asthmatic at 2 years or under (when asthma cannot be diagnosed reliably) suggests overdiagnosis of asthma may contribute to the apparent high prevalence.

Ratio of omega-6 to omega-3 fatty acids and childhood asthma.

UNLABELLED: Asthma is a leading cause of morbidity for children and is a major public health problem in Australia. Ecological and temporal data suggest that dietary factors may have a role in recent increases in the prevalence of asthma. AIM: The aim of conducting this study was to investigate whether childhood asthma was associated with the ratio of omega 6 (n-6) to omega 3 (n-3) fatty acids in the diet (n-6:n-3). METHOD: The Western Australian Pregnancy Cohort Study is a prospective birth cohort of 2602 children. Using a nested case-control cross-sectional study design within this cohort, a group of children were identified as cases with current asthma at 6 or at 8 years of age or as controls with no asthma at 6 or at 8 years. Dietary details including n-6 and n-3 fatty acid intake data were collected by parent response to a questionnaire when the children were 8 years old. Logistical regression was used to compare quartiles of n-6:n-3 intake in cases and controls. Adjustment was made for covariates: gender, gestational age, breastfeeding, older siblings, maternal smoking during pregnancy, maternal age, maternal asthma, child's current age in months, body mass index, total energy intake, and antioxidant intake (vitamins A, C, E, and zinc). RESULTS: A response rate of 83% was achieved by providing complete data from 335 children [49% cases with current asthma (n = 166), 51% controls (n = 169)]. Following adjustment for covariates the association between the ratio of n-6:n-3 fatty acids and risk for current asthma was statistically significant (p = 0.022). CONCLUSION: We found evidence for a modulatory effect of the dietary n-6:n-3 fatty acid ratio on the presence of asthma in children. Our results provide evidence that promotion of a diet with increased n-3 fatty acids and reduced n-6 fatty acids to protect children against symptoms of asthma is warranted.

Iron status of young Vietnamese children in Australia.

OBJECTIVE: The aim of this study was to estimate the prevalence of iron deficiency in Vietnamese children living in Australia and to identify risk factors associated with iron deficiency. METHODS: A cohort of healthy term Vietnamese infants, were followed from birth (n = 210) to 18 months (n = 174) with anthropometry, dietary intake and feeding practices measured at seven time points. Socio-demographic data were collected from the parents at the first home visit. At 18 months iron status was examined by full blood count and plasma ferritin concentration in 129/152 (85%) of the eligible children. Iron depletion was defined as a plasma ferritin level < 10 microg/L. Iron deficiency without anaemia was defined as iron depletion plus MCV < 70fl and iron deficiency anaemia was defined as iron deficiency anaemia plus Hb < 110 g/L. RESULTS: The prevalence of iron deficiency was iron depletion 19.4% (95% CI: 13.0%, 27.3%), iron deficiency without anaemia 3.1% (95% CI: 0.9%, 7.8%) and iron deficiency anaemia 3.9% (95% CI: 1.3%, 8.8%). Multiple regression analysis showed three significant predictors of iron deficiency: cows milk intake (negative effect), meat, fish or poultry intake (positive effect) and weight gain (negative effect). A cows milk intake > or = 650 mL/day was a risk factor for iron deficiency. CONCLUSION: Prevalence of iron deficiency at 18 months was high despite appropriate infant feeding practices during the first year. Modification of the diet in the second year of life may decrease the risk of iron deficiency in Vietnamese children.

Symptoms of persistent allergic rhinitis during a full calendar year in house dust mite-sensitive subjects.

BACKGROUND: Little is known about the natural course of persistent rhinitis symptoms over a prolonged period. OBJECTIVE: To describe the frequency and severity of nasal symptoms and quality of life (QoL) in house dust mite-sensitive persistent rhinitic subjects and to determine if medication use was related to symptoms. METHODS: Rhinitics and controls were telephoned fortnightly for 1 year to monitor symptoms. QoL was measured every 3 months. RESULTS: Thirty-seven rhinitics and 19 controls completed the study. Total nasal symptom scores (TNSS) were 'high' for 65% (95% CI +/- 6%) of the year in rhinitic subjects. When TNSS increased by 1, the likelihood of nasal medication use increased by 25% (95% CI: 7-46%). General and specific QoL were worse in rhinitic subjects than controls (P < 0.04 and <0.0001). Rhinitics with pollen allergy (n = 21) had seasonal variation in the frequency of high nasal symptom scores (P = 0.02). CONCLUSION: Nasal symptom scores were consistently high in rhinitics, and their QoL was worse than controls, even in general QoL. An increase in nasal symptom score increased the likelihood of nasal medication use. These findings help to characterize the course of persistent rhinitis over a previously unstudied period of 1 year.

Association between nasal and bronchial symptoms in subjects with persistent allergic rhinitis.

BACKGROUND: The association between nasal and bronchial symptoms, and the course of bronchial responsiveness and airway inflammation in house dust mite sensitive persistent rhinitis over a prolonged time period has not been thoroughly explored. OBJECTIVE: To determine if nasal symptoms were associated with bronchial symptoms in persistent rhinitic subjects, and to assess their bronchial responsiveness and airway inflammation in comparison to nonrhinitic, nonatopic controls. The additional impact of pollen sensitivity on the lower airways in rhinitic subjects was also addressed. METHODS: Rhinitics and controls answered telephone symptom questionnaires once every 2 weeks for 1 year. Every 3 months, exhaled nitric oxide (eNO) and bronchial responsiveness to histamine were measured. RESULTS: Thirty-seven rhinitics and 19 controls completed the study. High nasal symptom scores in rhinitic subjects were associated with bronchial symptoms (OR = 1.7, 95% CI 1.2-2.5). Bronchial hyper-responsiveness was present in 32.4% of rhinitic subjects on at least one clinical visit during the year. Pollen allergy caused seasonal variation in eNO (P = 0.03). CONCLUSION: In persistent rhinitic subjects, high nasal symptom scores were associated with bronchial symptoms, and many subjects experienced bronchial hyper-responsiveness during the year. Persistent rhinitic subjects were more at risk than healthy adults of bronchial symptoms and airway inflammation, which are likely risk factors for asthma.

Growth and feeding practices of Vietnamese infants in Australia.

OBJECTIVE: To investigate the growth and feeding practices in first-generation Vietnamese infants living in Australia. DESIGN: Cohort study. SETTING: The study was conducted between 1999 and 2002 in Sydney. SUBJECTS: A total of 239 Vietnamese women were recruited randomly from antenatal clinics, and of these 210 were initially seen. During the first year, 20 cases (9.5%) were lost to follow-up. Data were collected at 0.5, 2, 4, 6, 9 and 12 months. RESULTS: Vietnamese infants were significantly longer and heavier than reference data (both P<0.0001). The Vietnamese infants had a significant decline in weight growth with age compared with reference data (P<0.001). The Vietnamese infants had marginally higher s.d. score for ideal weight for length than reference data (P=0.044). There was a significant decline in ideal weight for length with age compared with reference data (P=0.0065). Both parents were significantly shorter (mean s.d. height scores: -1.5+/-0.8 (mother) and -1.8+/-0.8 (father)) than reference data (P<0.001). The incidence of breast feeding was 79%, but half of the breast feeding women had stopped breast feeding by 3 months. A total of 162 (79.8%) infants were given infant formula within the first week, of whom 131 (80.1%) were fed infant formula within the first 24 h after birth. CONCLUSIONS: Vietnamese infants in this study had growth comparable with reference data despite their parents being shorter than reference data. Breast feeding duration was short with infant formula being introduced early.

Childhood factors that predict asthma in young adulthood.

Predicting adult asthma, using childhood characteristics, is important for advising on prognosis and, potentially, for secondary prevention. A novel use of multivariate likelihood ratios (LRs) to quantify prognosis is described here. Of 718 subjects of a community-based cohort, 575 (80%) members were recruited at age 8-10 yrs and were re-assessed 15-17 yrs later. At baseline, information about symptoms, spirometry, histamine challenge and skin-prick tests were collected. At follow-up "asthma symptoms" were defined as wheeze, sleep disturbance from asthma or inhaled steroid use within the previous year. LRs were calculated for significant predictors of this outcome. Shinkage factors were applied to yield multivariate LRs. Childhood characteristics that independently predicted asthma symptoms in adulthood were obstructive spirometry (adjusted (adj)LR 2.9, 95% confidence interval (CI) 1.3-6.5), airway hyperresponsiveness (adjLR 2.6, 95% CI 1.8-3.7), atopy (adjLR 2.0, 95% CI 1.5-2.7), recent wheeze (adjLR 1.9, 95% CI 1.5-2.5) and being female (adjLR 1.29, 95% CI 0.8-2.1). Children with all five characteristics had a cumulative LR of 36.9 for asthma symptoms in adulthood. Most adults who had asthma symptoms did not have manifestations of asthma as children. However, the presence of obstructive spirometry, airway hyperresponsiveness and atopy in childhood identifies individuals with increased likelihood of having asthma in adulthood. Cumulative likelihood ratios are more valuable than odds ratios for quantifying risk in individuals and for identifying people with most to gain from preventive interventions.

Asthma and atopy in overweight children.

BACKGROUND: Obesity may be associated with an increase in asthma and atopy in children. If so, the effect could be due to an effect of obesity on lung volume and thus airway hyperresponsiveness. METHODS: Data from 5993 caucasian children aged 7-12 years from seven epidemiological studies performed in NSW were analysed. Subjects were included if data were available for height, weight, age, skin prick test results to a common panel of aeroallergens, and a measure of airway responsiveness. History of doctor diagnosed asthma, wheeze, cough, and medication use was obtained by questionnaire. Recent asthma was defined as a doctor diagnosis of asthma ever and wheeze in the last 12 months. Body mass index (BMI) percentiles, divided into quintiles per year age, were used as a measure of standardised weight. Dose response ratio (DRR) was used as a measure of airway responsiveness. Airway hyperresponsiveness was defined as a DRR of >/=8.1. Adjusted odds ratios were obtained by logistic regression. RESULTS: After adjusting for atopy, sex, age, smoking and family history, BMI was a significant risk factor for wheeze ever (OR = 1.06, p = 0.007) and cough (OR = 1.08, p = 0.001), but not for recent asthma (OR = 1.02, p = 0.43) or airway hyperresponsiveness (OR = 0.97 p = 0.17). In girls a higher BMI was significantly associated with higher prevalence of atopy (chi(2) trend 7.9, p = 0.005), wheeze ever (chi(2) trend 10.4, p = 0.001), and cough (chi(2) trend 12.3, p<0.001). These were not significant in boys. CONCLUSIONS: Higher BMI is a risk factor for atopy, wheeze ever, and cough in girls only. Higher BMI is not a risk factor for asthma or airway hyperresponsiveness in either boys or girls.

Effectiveness of an intervention to reduce house dust mite allergen levels in children's beds.

BACKGROUND: In temperate climates, exposure to house dust mite (HDM) allergens is the strongest environmental risk factor for childhood asthma. Environmental modifications to limit exposure have the potential to reduce the prevalence of asthma. The aim of this study was to reduce allergen exposure for children at high risk of developing asthma. METHODS: A total of 616 pregnant women were randomized to HDM intervention and control groups. The control group had no special recommendations whereas the intervention group was given allergen impermeable mattress covers and an acaricidal washing detergent for bedding. Children were visited regularly until 18 months of age to have dust collected from their bed. RESULTS: Der p 1 concentrations in the control group increased from 5.20 microg/g at 1 month to 22.18 microg/g at 18 months but remained low in the intervention group, ranging from 3.27 microg/g at 1 month to 6.12 microg/g at 18 months. CONCLUSIONS: In a high HDM allergen environment, a combined approach using physical barriers and an acaricidal wash, is effective in reducing HDM allergen concentrations in bedding. However, even with these control measures in place, HDM allergen levels remained high by international standards.

Pregnancy and birth outcomes in families with asthma.

Studies of maternal asthma in pregnancy have shown an increased risk of adverse neonatal and maternal outcomes such as preeclampsia, hypertension, cesarean delivery, prematurity, low birth weight, and perinatal/neonatal mortality. However, results are not consistent between studies. We studied the association between maternal asthma and various adverse neonatal and maternal outcomes and explored whether there is any evidence that pregnancy exacerbates maternal asthma. The data were collected as part of the Childhood Asthma Prevention Study. Pregnant women with asthma or women whose partners or other children had current symptoms of asthma were recruited at six Sydney hospitals. All women recruited were post 36 weeks gestation and were living within 30 km of the study recruitment center. Information about family history of asthma was collected using a questionnaire at 36 weeks gestation and subsequent information about antenatal and perinatal events was obtained from hospital records. Data from 611 pregnant women were available for analysis, 340 of whom had asthma. Hypertension was significantly more common in asthmatics than in nonasthmatics [OR = 2.16 (1.02-4.6), p < 0.043]. The prevalence of gestational diabetes, labor complications, delivery complications, and adverse neonatal outcomes did not differ significantly between the groups. We also found that the course of maternal asthma usually remains unchanged during pregnancy, but that more severe asthma is likely to get worse. We have confirmed previous observations that women with asthma are at increased risk of hypertension in pregnancy, which is consistent with studies that show that pregnant asthmatic women have a slightly increased risk of preeclampsia. However, we did not find evidence of an increased risk of adverse perinatal outcomes.

Gastroschisis: determinants of neonatal outcome.

This retrospective study elicits information regarding the dependence of neonatal outcome in gastroschisis upon: (1) the mode of delivery, (2) place of birth, (3) time for birth to surgery, (4) method of closure, (5) time from operation to commencement of first enteral feeds. The neonatal intensive care database from five major tertiary centres was used to identify 181 neonates with gastroschisis from 1990 to 2000. There were 8 deaths. There were no significant differences in outcome for infants delivered vaginally (102) versus Caesarean section (79), those born near the tertiary centre (133) as compared to infants born away (48), ones operated within 7 hours (125) compared with those operated after 7 hours (56), with delayed closure (30) versus primary closure (151). Neonates fed within 10 days of operation (85) had significantly lower incidence of sepsis, duration of TPN and hospital stay when compared to those fed after 10 days (96). Early commencement of feeds decreases the incidence of sepsis, duration of total parenteral nutrition (TPN) and hospital stay. Place of delivery, mode of delivery, time to surgery and type of closure do not influence neonatal outcome.

Use of a paper disposable cup as a spacer is effective for the first-aid management of asthma.

OBJECTIVE: There are many settings in which a spacer device is not available for the administration of bronchodilator. Therefore, we tested whether a paper disposable cup is as effective as a commercially produced spacer to administer bronchodilator. METHODOLOGY: Randomised controlled trial. 50 subjects aged 16-50 years who had wheeze and a greater than 10% decrease in FEV1 after histamine inhalation test (HIT). Subjects were randomised to either the 150 ml paper disposable cup group (CUP) or the commercially produced spacer group (SPACER). Twenty minutes after 400 microg salbutamol was administered FEV1 was measured. The recovery index measured post-bronchodilator FEV1 as a percentage of baseline FEV1. Also, analysis of covariance tested whether recovery of FEV1 was related to the magnitude of the fall following the HIT. RESULTS: There were no statistically significant differences between CUP and SPACER groups in any characteristics. There was no difference for the recovery index (t48=1.14, P=0.26). Regression analyses showed that the relation between the magnitude of the fall in FEV1 during the HIT and the percent recovery was not different between the CUP and SPACER groups (t=-1.2, P<0.23). CONCLUSIONS: A paper disposable cup was effective for the reversal of mild to moderate bronchoconstriction. Therefore, a paper disposable cup can be used for the first-aid management of asthma when there is concern about cross-infection and a commercially produced spacer is not available.

Predictors of high house dust mite allergen concentrations in residential homes in Sydney.

BACKGROUND: In parts of coastal Australia, house dust mite allergen concentrations in homes are often very high with at least 80% of homes in Sydney exceeding concentrations of 10 microg of allergen per gram of fine dust. In this study, we report the relation between characteristics of the home environment and house dust mite allergen concentrations at three sites in Sydney homes. METHODS: A total of 616 families were recruited as part of the Childhood Asthma Prevention Study (CAPS). Information about the home environment and structural aspects of the home was collected using a questionnaire. Samples of dust were collected from the parents' bed, the bedroom floor and the living room floor and assayed for Der p 1. RESULTS: A total of 68% of participants' beds, 65% of bedroom floors and 56% of living room floors had Der p 1 concentrations above 10 microg/g, with the highest concentrations of allergen in the bed. The most significant predictor of high Der p 1 concentrations in the bed and floors was the age of the home. We also found that beds with mattresses over two years old and with woollen or synthetic blankets or synthetic quilts had higher Der p 1 concentrations. Carpeted floors had higher Der p 1 concentrations than hard floors. CONCLUSION: The finding that high Der p 1 allergen concentrations in homes with carpets and older mattresses indicates that control strategies directed at these sources are likely to be effective in reducing exposure. Alternatives such as the use of house dust mite impermeable mattress encasings on older mattresses may also be effective in reducing exposure.

Family and parenting interventions for conduct disorder and delinquency: a meta-analysis of randomised controlled trials.

AIMS: To determine whether family and parenting interventions benefit children and adolescents with conduct disorder and delinquency. METHODS: Meta-analysis of eight randomised controlled trials involving 749 children and adolescents (aged 10-17 years) with conduct disorder and/or delinquency. Criminality, academic performance, future employment, problem behaviour, family functioning, parental mental health, and peer relations were evaluated. RESULTS: Family and parenting interventions significantly reduced the time spent by juvenile delinquents in institutions (weighted mean difference 51.34 days). There was also a significant reduction in the risk of a juvenile delinquent being rearrested (relative risk 0.66) and in their rate of subsequent arrests at 1-3 years (standardised mean difference -0.56). CONCLUSIONS: The evidence suggests that family and parenting interventions for juvenile delinquents and their families have beneficial effects on reducing time spent in institutions and their criminal activity. In addition to the obvious benefit to the participant and their family, this may result in a cost saving for society.

Risk factors for onset and remission of atopy, wheeze, and airway hyperresponsiveness.

BACKGROUND: Although many children with asthma may have a remission as they grow and other children who did not have asthma may develop asthma in adult life, knowledge about the factors that influence the onset and prognosis of asthma during adolescence and young adulthood is very limited. METHODS: A cohort of 8-10 year old children (n=718) living in Belmont, New South Wales, Australia were surveyed six times at 2 yearly intervals from 1982 to 1992, and then again 5 years later in 1997. From this cohort, 498 subjects had between three and seven assessments and were included in the analysis. Atopy, airway hyperresponsiveness (AHR), and wheeze in the last 12 months were measured at each survey. Late onset, remission, and persistence were defined based on characteristics at the initial survey and the changes in characteristics at the follow up surveys. RESULTS: The proportion of subjects with late onset atopy (13.7%) and wheeze (12.4%) was greater than the proportion with remission of atopy (3.2%) and wheeze (5.6%). Having atopy at age 8-12 years (OR 2.8, 95% CI 1.5 to 5.1) and having a parental history of asthma (OR 2.0, 95% CI 1.02 to 4.13) were significant risk factors for the onset of wheeze. Having AHR at age 8-12 years was a significant risk factor for the persistence of wheeze (OR 4.3, 95% CI 1.3 to 15.0). Female sex (OR 1.9, 95% CI 1.01 to 3.60) was a significant risk factor for late onset AHR whereas male sex (OR 1.9, 95% CI 1.1 to 2.8) was a significant risk factor for late onset atopy. CONCLUSIONS: The onset of AHR is uncommon during adolescence, but the risk of acquiring atopy and recent wheeze for the first time continues during this period. Atopy, particularly present at the age of 8-10 years, predicts the subsequent onset of wheeze.

Excision duodenoplasty: a new technique for congenital duodenal obstruction.

Slow anastomotic function is a common problem in the management of congenital duodenal obstruction. We describe a simple technique of excision duodenoplasty (ED) that results in a fixed open anastomosis, which facilitates early commencement of feeds and discharge from hospital. A retrospective case-note review (1981-2000) was undertaken to compare the results of ED with side-to-side duodenoplasty (SSD) and diamond-shaped anastomosis (DD). The outcome measures were days to commencement of feeds, duration of total parenteral nutrition (TPN), and length of hospital stay. In ED a 1.0 to 1.5-cm elliptical segment of dilated duodenum is excised. A longitudinal incision is made in the smaller distal duodenum. A side-to-side one-layer anastomosis is performed. The wall of the proximal duodenal stump is thick, and excision of the ellipse keeps the anastomosis open by preventing apposition of the opposing walls. This facilitates good drainage across the anastomosis. The time to onset of feeding was longer after SSD (median 7 days) compared to ED (5 days) and DD (5 days). The total duration of TPN was also longer for SSD (9 days) in comparison to ED (7 days) and DD (7 days). Although the duration of hospital stay was more for SSD (18 days) than ED (13 days) and DD (16 days), this difference was not statistically significant. The ED technique thus gives an equally good result as DD and a better result than SSD. It is simple to perform and to teach.

Abdominal fat and birth size in healthy prepubertal children.

BACKGROUND: Studies examining the foetal origins hypothesis suggest that small birth size may be a marker of foetal adaptations that programme future propensity to adult disease. We explore the hypothesis that birth size may relate to fat distribution in childhood and that fat distribution may be a link between birth size and adult disease. OBJECTIVE: To investigate the relationship between birth size and abdominal fat, blood pressure, lipids, insulin and insulin:glucose ratio in prepubertal children. DESIGN: Cross-sectional study, based on a birth cohort of consecutive full-term births. SUBJECTS: Two hundred and fifty-five (137 females) healthy, 7- and 8-y-old children. MEASUREMENTS: Body composition and abdominal fat was measured by dual energy X-ray absorptiometry. Lipid, glucose and insulin profiles were measured after an overnight fast and an automated BP monitor was used for blood pressure measurements. RESULTS: There was a negative association between abdominal fat and birth weight s.d. score across a range of normal birth weights (beta=-0.18; 95% CI=-0.31 to -0.04, P=0.009) and a positive association with weight s.d. score at 7/8 y (beta=0.35; 95% CI=0.24 to 0.46, P<0.001). Children who were born with the lowest weight s.d. score and had the greatest weight s.d. score at 7/8 y had significantly more (P<0.001) abdominal fat, as a percentage of total fat (6.53+/-1.3%) than those who had the highest birth weight s.d. score and the lowest weight s.d. score at 7/8 y (4.14+/-0.5%). Similar results were seen if head circumference, but not ponderal index, was used as an indicator of birth size. Increased abdominal fat was associated with higher total cholesterol:HDL cholesterol, higher triglyceride concentration and increased diastolic blood pressure. CONCLUSIONS: Birth weight independently predicted abdominal fat. Children with the highest amount of abdominal fat were those who tended to be born lighter and gained weight centiles. Increased abdominal fat was associated with precursor risk factors for ischaemic heart disease.

Predictors of house-dust-mite allergen concentrations in dry regions in Australia.

BACKGROUND: House-dust-mite allergen content differs between houses and is thought to be a function of the housing characteristics and furnishing choices that affect indoor microclimate and mite proliferation. The importance of these features may differ with regional climates. METHODS: Concentrations of mite allergen were analysed as a function of housing features. Information on housing features was collected by questionnaire in 50 houses in two towns in a dry inland region of Australia. Mite allergen (Der p 1) was measured by ELISA in dust samples collected on five occasions over 2 years from beds and floors. RESULTS: Der p 1 was detected in all houses. Many housing features did not influence mite allergen concentrations. However, the presence of evaporative cooling increased mite allergen by 3.34-fold in beds (P=0.007) and 3.94-fold in floors (P=0.003). Mite allergen was threefold higher in mattresses >5 years old, and synthetic and feather duvets tended to have higher and lower levels of mite allergen, respectively. CONCLUSIONS: In houses in dry, inland regions of Australia, evaporative cooling and older mattresses are associated with higher concentrations of mite allergen. Alternative forms of air conditioning to evaporative cooling may be useful for control of mite allergen in dry regions.