Pm Clark

Risk factors for atopic dermatitis in New Zealand children at 3·5 years of age

Background  The prevalence of atopic dermatitis (AD) is increasing in Western societies. The hygiene hypothesis proposes that this is due to reduced exposure to environmental allergens and infections during early life.

Risk factors for small-for-gestational-age babies: The Auckland Birthweight Collaborative Study.

Objective: This case‐control study determined whether internationally recognized risk factors for small‐for‐gestational‐age (SGA) term babies were applicable in New Zealand.

Risk factors for obesity in 7-year-old European children: the Auckland Birthweight Collaborative Study

Objective: To identify risk factors associated with obesity in primary school children, with a particular focus on those which can be modified. To identify critical periods and growth patterns in the development of childhood obesity. Methods: 871 New Zealand European children were enrolled in a longitudinal study at birth and data were collected at birth, 1, 3.5 and 7 years of age. Data collected at 7 years included weight, height, bioelectrical impedance analysis (BIA), television viewing time and a 24 h body movement record (actigraphy). The outcome measure was percentage body fat (PBF), which was calculated at 3.5 and 7 years using BIA. Univariate and multiple regression analyses were carried out using PBF as a continuous variable. Results: Multivariable analysis found maternal overweight/obesity, maternal age, female gender, sedentary activity time and hours of television viewing to be independently associated with PBF at 7 years. Growth variables (birth weight, rapid weight gain in infancy, early (1–3.5 years) and middle childhood (3.5–7 years)) were also independently associated with adiposity at 7 years. There was a strong correlation between PBF at 3.5 years and PBF at 7 years. Conclusions: Many primary school aged children start on the trajectory of obesity in the preschool years, which suggests interventions need to start early. Maternal overweight/obesity, television watching, sedentary activity time and rapid weight gain in infancy, early and middle childhood are risk factors for childhood obesity, and are all potentially modifiable.

Maternal nutritional risk factors for small for gestational age babies in a developed country: a case-control study

Aims: To assess the effect of maternal diet during pregnancy on the risk of delivering a baby who is small for gestational age (SGA). Methods: Case-control study of 844 cases (SGA) and 870 controls (appropriate size for gestational age (AGA)). Only term (37+ completed weeks of gestation) infants were included. Retrospective food frequency questionnaires were completed at birth on the diet at the time of conception and in the last month of pregnancy. Results: At the time of conception, mothers of AGA infants ate significantly more servings of carbohydrate rich food and fruit, and were more likely to have taken folate and vitamin supplements than mothers of SGA infants. There was some evidence that mothers of AGA infants also ate more servings of dairy products, meat, and fish (0.05 < p < 0.1). However, after adjustment for maternal ethnicity, smoking, height, weight, hypertension, and occupation, fish intake (p  =  0.04), carbohydrate-rich foods (p  =  0.04), and folate supplementation (p  =  0.02) were associated with a reduced risk of SGA. In the last month of pregnancy, only iron supplementation was associated with a reduced risk of SGA (p  =  0.05) after adjustment for potential confounders. Conclusions: This study suggests that small variations in maternal diets within the normal range during pregnancy in developed countries are associated with differences in birth weight.

Smoking, nicotine and tar and risk of small for gestational age babies

Aims: To assess the effect of maternal smoking and environmental tobacco smoke (ETS) on risk of small for gestational age infants (SGA). Methods: Case‐control study of 844 cases and 870 controls. Results: Maternal smoking in pregnancy was associated with an increased risk of SGA (adjusted odds ratio (OR) = 2.41; 95% confidence interval (CI) = 1.78, 3.28). We could not detect an increased risk of SGA with paternal smoking, or with other household smokers when the mother was a non‐smoker, but did find an increased risk with exposure to ETS in the workplace or while socializing. Infants of mothers who ceased smoking during pregnancy were not at increased risk of SGA, but those who decreased but did not stop remained at risk of SGA. There was no evidence that the concentration of nicotine and tar in the cigarettes influenced the risk of SGA.

Breastfeeding and intelligence of preschool children

AIM To investigate whether breastfeeding during infancy is a determinant of intelligence at 3.5 y. METHODS Five hundred and fifty European children enrolled at birth in the Auckland Birthweight Collaborative Study were assessed at 3.5 y of age. Approximately half were small for gestational age (SGA < or =10th percentile) at birth and half were appropriate for gestational age (AGA >10th percentile). Duration of breastfeeding was recorded at maternal interview, and the intelligence of children was assessed using the Stanford Binet Intelligence Scale. Regression analysis was used to calculate estimates of difference in intelligence scores between breastfeeding groups for the total sample and the group of SGA children. Analyses of the total sample were weighted to account for the disproportionate sampling of SGA children. RESULTS Breastfeeding was not significantly related to intelligence scores in the total sample despite a trend for longer periods of breastfeeding to be associated with higher intelligence scores. However, in the SGA group, breastfeeding was significantly related to IQ at 3.5 y. Small for gestational age children who were breastfed for longer than 12 mo had adjusted scores 6.0 points higher than those who were not breastfed (p=0.06). CONCLUSION Breastfeeding may be particularly important for the cognitive development of preschool children born small for gestational age.

Falling asleep: the determinants of sleep latency.

Background: Difficulty falling asleep (prolonged sleep latency) is a frequently reported problem in school-aged children. Aims: This study aimed to describe the distribution of sleep latency and factors that influence its duration. Methods: 871 children of European mothers were recruited at birth. 591 (67.9%) children took part in the follow-up at 7 years of age. Sleep and daytime activity were measured objectively by an actigraph worn for 24 h. Results: Complete sleep data were available for 519 children (87.8%) with a mean age of 7.3 years (SD 0.2). Median sleep latency was 26 minutes (interquartile range 13–42). Higher mean daytime activity counts were associated with a decrease in sleep latency (−1.2 minutes per 102 movement count per minute, p = 0.05). Time spent in sedentary activity was associated with an increase in sleep latency (3.1 minutes per hour of sedentary activity, p = 0.01). Conclusions: These findings emphasise the importance of physical activity for children, not only for fitness, cardiovascular health and weight control, but also for promoting good sleep.

Stress and lack of social support as risk factors for small‐for‐gestational‐age birth

Aim: To determine the contributions of social support and perceived stress to the risk of small‐for‐gestational‐age birth. Methods: The investigation was a case‐control study of mothers of infants born at 37 or more completed weeks of gestation. Cases weighed less than the sex‐specific 10th percentile for gestational age at birth (small for gestational age (SGA), n= 836), and controls (appropriate for gestational age (AGA), n= 870) comprised a random selection of heavier babies. Results: In univariate analyses measures of informal social support, but not perceived stress or formal social support, were associated with SGA birth. It was found that Asian mothers are less likely to receive support from families and friends. After adjustment for ethnicity, informal social support was not associated with SGA.

Children with physical disability: Gaps in service provision, problems joining in

Aim:  To describe the reported experiences of the estimated 14 500 New Zealand children with a physical disability and those of their families and whanau (extended families).

Risk factors for asthma at 3.5 and 7 years of age

Background It has been suggested that factors in early life including exposure to allergens and microbes may influence the development of asthma.