Seema Mihrshahi

The Childhood Asthma Prevention Study (CAPS): Design and Research Protocol of a Randomized Trial for the Primary Prevention of Asthma

The Childhood Asthma Prevention Study is a randomized controlled trial to measure whether the incidence of atopy and asthma can be reduced by house dust mite allergen reduction, a diet supplemented with omega-3 fatty acids, or a combination of both interventions. Six hundred and sixteen pregnant women whose unborn children were at high risk of developing asthma because of a family history were randomized prenatally. Study groups are as follows: Group A (placebo diet intervention, no house dust mite reduction), Group B (placebo diet intervention, active house dust mite reduction), Group C (active diet intervention, no house dust mite reduction), and Group D (active diet intervention, active house dust mite reduction). The house dust mite reduction intervention comprises use of physical and chemical methods to reduce allergen contact. The dietary intervention comprises use of a daily oil supplement from 6 months or at onset of bottle-feeding, and use of margarine and cooking oils based on sunflower or canola oils to increase omega-3 dietary intake. Data is collected quarterly until the infant is 1 year old and then half yearly until age 5 years. Questionnaires are used to collect respiratory illness history and information about diet and home environment. Dust is collected from the childs bed and bedroom and playroom floors. Blinded assessments are conducted at 18 months, 3 years, and 5 years. Skin prick tests to common allergens, blood tests, and detailed illness, medication use, and vaccination histories are collected. Primary outcomes will be the development of allergic sensitization and the presence and severity of asthma. This study is designed to measure the effectiveness of allergen reduction and dietary supplementation, both separately and in combination, for the primary prevention of atopy and asthma. The results of this study may have important implications for public health policies to reduce the incidence of childhood asthma. Control Clin Trials 2001;22:333-354

Ratio of Omega-6 to Omega-3 Fatty Acids and Childhood Asthma

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, childs 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.

The association between infant feeding practices and subsequent atopy among children with a family history of asthma.

Background Although longer duration of breastfeeding and later introduction of solid foods are both recommended for the prevention of asthma and allergic disease, evidence to support these recommendations is controversial.

Determinants of rapid weight gain during infancy: baseline results from the NOURISH randomised controlled trial

BackgroundRapid weight gain in infancy is an important predictor of obesity in later childhood. Our aim was to determine which modifiable variables are associated with rapid weight gain in early life.MethodsSubjects were healthy infants enrolled in NOURISH, a randomised, controlled trial evaluating an intervention to promote positive early feeding practices. This analysis used the birth and baseline data for NOURISH. Birthweight was collected from hospital records and infants were also weighed at baseline assessment when they were aged 4-7 months and before randomisation. Infant feeding practices and demographic variables were collected from the mother using a self administered questionnaire. Rapid weight gain was defined as an increase in weight-for-age Z-score (using WHO standards) above 0.67 SD from birth to baseline assessment, which is interpreted clinically as crossing centile lines on a growth chart. Variables associated with rapid weight gain were evaluated using a multivariable logistic regression model.ResultsComplete data were available for 612 infants (88% of the total sample recruited) with a mean (SD) age of 4.3 (1.0) months at baseline assessment. After adjusting for mothers age, smoking in pregnancy, BMI, and education and infant birthweight, age, gender and introduction of solid foods, the only two modifiable factors associated with rapid weight gain to attain statistical significance were formula feeding [OR = 1.72 (95%CI 1.01-2.94), P = 0.047] and feeding on schedule [OR = 2.29 (95%CI 1.14-4.61), P = 0.020]. Male gender and lower birthweight were non-modifiable factors associated with rapid weight gain.ConclusionsThis analysis supports the contention that there is an association between formula feeding, feeding to schedule and weight gain in the first months of life. Mechanisms may include the actual content of formula milk (e.g. higher protein intake) or differences in feeding styles, such as feeding to schedule, which increase the risk of overfeeding.Trial RegistrationAustralian Clinical Trials Registry ACTRN12608000056392

Effect of omega‐3 fatty acid concentrations in plasma on symptoms of asthma at 18 months of age

The objective of this study was to assess the relation between observed levels of omega‐3 fatty acids in plasma and symptoms of asthma and atopy in children at 18 months of age. A total of 616 women at risk of having a child who would develop asthma because of a family history were recruited from the antenatal clinics of six hospitals in Sydney, Australia. Families were randomized to either active omega‐3 supplemented or control group. The active group received a daily tuna fish oil supplement and omega‐3‐rich margarines and cooking oils and the control group received a placebo supplement with polyunsaturated margarines and cooking oils. When the children were 18 months of age an assessment of symptoms was carried out by a research nurse blinded to treatment group allocation. Atopy was measured by skin prick tests, blood was collected to determine serum immunoglobulin E (IgE), and plasma fatty acid concentrations. A total of 376 children (61.0% of total recruited) completed an assessment at 18 months and had blood taken to determine plasma fatty acid concentrations. Omega‐3 fatty acid levels were expressed in quintiles of exposure ‘as treated’ without reference to treatment group allocation. Wheeze ever, doctor visits for wheeze, bronchodilator use and nocturnal coughing were significantly reduced in children in the higher exposure quintiles. Serum IgE was reduced in the highest quintile but not significantly so. There was no difference in diagnosed asthma or atopy between the exposure quintiles. Although wheeze at this age may not be a good indicator of asthma in later childhood, it is encouraging that some symptoms have been reduced in children with high omega‐3 fatty acid concentrations in plasma.

Determinants of Infant and Young Child Feeding Practices in Bangladesh: Secondary Data Analysis of Demographic and Health Survey 2004

Background In Bangladesh, poor infant and young child feeding practices are contributing to the burden of infectious diseases and malnutrition. Objective To estimate the determinants of selected feeding practices and key indicators of breastfeeding and complementary feeding in Bangladesh. Methods The sample included 2,482 children aged 0 to 23 months from the Bangladesh Demographic and Health Survey of 2004. The World Health Organization (WHO)-recommended infant and young child feeding indicators were estimated, and selected feeding indicators were examined against a set of individual-, household-, and community-level variables using univariate and multivariate analyses. Results Only 27.5% of mothers initiated breastfeeding within the first hour after birth, 99.9% had ever breastfed their infants, 97.3% were currently breastfeeding, and 22.4% were currently bottle-feeding. Among infants under 6 months of age, 42.5% were exclusively breastfed, and among those aged 6 to 9 months, 62.3% received complementary foods in addition to breastmilk. Among the risk factors for an infant not being exclusively breastfed were higher socioeconomic status, higher maternal education, and living in the Dhaka region. Higher birth order and female sex were associated with increased rates of exclusive breastfeeding of infants under 6 months of age. The risk factors for bottle-feeding were similar and included having a partner with a higher educational level (OR = 2.17), older maternal age (OR for age ≥ 35 years = 2.32), and being in the upper wealth quintiles (OR for the richest = 3.43). Urban mothers were at higher risk for not initiating breastfeeding within the first hour after birth (OR = 1.61). Those who made three to six visits to the antenatal clinic were at lower risk for not initiating breastfeeding within the first hour (OR = 0.61). The rate of initiating breastfeeding within the first hour was higher in mothers from richer households (OR = 0.37). Conclusions Most breastfeeding indicators in Bangladesh were below acceptable levels. Breastfeeding promotion programs in Bangladesh need nationwide application because of the low rates of appropriate infant feeding indicators, but they should also target women who have the main risk factors, i.e., working mothers living in urban areas (particularly in Dhaka).

Determinants of inappropriate complementary feeding practices in infant and young children in Bangladesh: secondary data analysis of Demographic Health Survey 2007

Suboptimal and inappropriate complementary feeding practices are one of the major causes of child undernutrition in the first 2 years of life in South Asian countries including Bangladesh. The aim of this study was to use the newly developed World Health Organization infant feeding indicators to identify the potential risk factors associated with inappropriate complementary feeding practices. We used data for 1728 children aged 6-23 months obtained from nationally representative data from the 2007 Bangladesh Demographic and Health Survey to assess the association between complementary feeding and other characteristics using multivariate models. Only 71% of infants were consuming soft, semi-solid and solid food by 6-8 months of age. In the multivariate analysis, mothers who had no education had a higher risk for not introducing timely complementary feeds [adjusted odds ratio (AOR)=2.14; 95% confidence interval (CI): 1.08-4.23, P=0.03], not meeting the minimum dietary diversity (AOR=1.69; 95% CI: 1.14-2.54, P=0.01), minimum acceptable diet (AOR=1.70, 95% CI: 1.09-2.67, P=0.02) and minimum meal frequency (AOR=1.73; 95% CI: 1.20-2.49, P=0.003) than the mothers who had secondary or higher education. Infants born in Sylhet, Chittagong and Barisal division had higher risks for not meeting minimum dietary diversity, meal frequency and acceptable diet (P<0.001). The poorest two quintiles had poor levels of minimum meal frequency but dietary quality improved with age. In Bangladesh addressing the fourth Millennium Development Goal (MDG) target will require substantial improvement in complementary feeding practices. Appropriate Infant and Young Child feeding massages should to be development and delivered through existing health system.

Association between infant feeding patterns and diarrhoeal and respiratory illness: A cohort study in Chittagong, Bangladesh

BackgroundIn developing countries, infectious diseases such as diarrhoea and acute respiratory infections are the main cause of mortality and morbidity in infants aged less than one year. The importance of exclusive breastfeeding in the prevention of infectious diseases during infancy is well known. Although breastfeeding is almost universal in Bangladesh, the rates of exclusive breastfeeding remain low. This cohort study was designed to compare the prevalence of diarrhoea and acute respiratory infection (ARI) in infants according to their breastfeeding status in a prospective cohort of infants from birth to six months of age.MethodsA total of 351 pregnant women were recruited in the Anowara subdistrict of Chittagong. Breastfeeding practices and the 7-day prevalence of diarrhoea and ARI were recorded at monthly home visits. Prevalences were compared using chi-squared tests and logistic regression.ResultsA total of 272 mother-infant pairs completed the study to six months. Infants who were exclusively breastfed for six months had a significantly lower 7-day prevalence of diarrhoea [AOR for lack of EBF = 2.50 (95%CI 1.10, 5.69), p = 0.03] and a significantly lower 7-day prevalence of ARI [AOR for lack of EBF = 2.31 (95%CI 1.33, 4.00), p < 0.01] than infants who were not exclusively breastfed. However, when the association between patterns of infant feeding (exclusive, predominant and partial breastfeeding) and illness was investigated in more detail, there was no significant difference in the prevalence of diarrhoea between exclusively [6.6% (95% CI 2.8, 10.4)] and predominantly breastfed infants [3.7% (95% CI 0.09, 18.3), (p = 0.56)]. Partially breastfed infants had a higher prevalence of diarrhoea than the others [19.2% (95% CI 10.4, 27.9), (p = 0.01)]. Similarly, although there was a large difference in prevalence in acute respiratory illness between exclusively [54.2% (95%CI 46.6, 61.8)] and predominantly breastfed infants [70.4% (95%CI 53.2, 87.6)] there was no significant difference in the prevalence (p = 0.17).ConclusionThe findings suggest that exclusive or predominant breastfeeding can reduce rates of morbidity significantly in this region of rural Bangladesh.

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.

Recruiting and engaging new mothers in nutrition research studies: lessons from the Australian NOURISH randomised controlled trial

BackgroundDespite important implications for the budgets, statistical power and generalisability of research findings, detailed reports of recruitment and retention in randomised controlled trials (RCTs) are rare. The NOURISH RCT evaluated a community-based intervention for first-time mothers that promoted protective infant feeding practices as a primary prevention strategy for childhood obesity. The aim of this paper is to provide a detailed description and evaluation of the recruitment and retention strategies used.MethodsA two stage recruitment process designed to provide a consecutive sampling framework was used. First- time mothers delivering healthy term infants were initially approached in postnatal wards of the major maternity services in two Australian cities for consent to later contact (Stage 1). When infants were approximately four months old mothers were re-contacted by mail for enrolment (Stage 2), baseline measurements (Time 1) and subsequent random allocation to the intervention or control condition. Outcomes were assessed at infant ages 14 months (Time 2) and 24 months (Time 3).ResultsAt Stage 1, 86% of eligible mothers were approached and of these women, 76% consented to later contact. At Stage 2, 3% had become ineligible and 76% could be recontacted. Of the latter, 44% consented to full enrolment and were allocated. This represented 21% of mothers screened as eligible at Stage 1. Retention at Time 3 was 78%. Mothers who did not consent or discontinued the study were younger and less likely to have a university education.ConclusionsThe consent and retention rates of our sample of first time mothers are comparable with or better than other similar studies. The recruitment strategy used allowed for detailed information from non-consenters to be collected; thus selection bias could be estimated. Recommendations for future studies include being able to contact participants via mobile phone (particularly text messaging), offering home visits to reduce participant burden and considering the use of financial incentives to support participant retention.Trial registrationAustralian and New Zealand Clinical Trials Registry Number ACTRN12608000056392