Fetal growth and risk of childhood asthma and allergic disease

Introduction: Early genetic and environmental factors have been discussed as potential causes for the high prevalence of asthma and allergic disease in the western world, and knowledge on fetal growth and its consequence on future health and disease development is emerging. Objective: This review article is an attempt to summarize research on fetal growth and risk of asthma and allergic disease. Current knowledge and novel findings will be reviewed and open research questions identified, to give basic scientists, immunologists and clinicians an overview of an emerging research field. Methods: PubMed-search on pre-defined terms and cross-references. Results: Several studies have shown a correlation between low birth weight and/or gesta- tional age and asthma and high birth weight and/or gestational age and atopy. The exact mechanism is not yet clear but both environmental and genetic factors seem to contribute to fetal growth. Some of these factors are confounders that can be adjusted for, and twin studies have been very helpful in this context. Suggested mechanisms behind fetal growth are often linked to the feto-maternal circulation, including the development of placenta and umbilical cord. However, the causal link between fetal growth restriction and subse- quent asthma and allergic disease remains unexplained. New research regarding the catch-up growth following growth restriction has posited an alternative theory that dis- eases later on in life result from rapid catch-up growth rather than intrauterine growth restriction per se. Several studies have found a correlation between a rapid weight gain after birth and development of asthma or wheezing in childhood. Conclusion and clinical relevance: Asthma and allergic disease are multifactorial. Several mechanisms seem to influence their development. Additional studies are needed before we fully understand the causal links between fetal growth and development of asthma and allergic diseases.Swedish Research CouncilALF KI/SLLStrategic Research Program in Epidemiology at Karolinska InstitutetPublishe

No association between macrolide treatment in infancy and later pyloric stenosis in Sweden

NoneAccepte

Cohort profile : Swedish Twin Study on Prediction and Prevention of Asthma (STOPPA)

Asthma is a common childhood disease and several risk factors have been identified, however the impact of genes and environment is not fully understood. The aim of the Swedish Twin study On Prediction and Prevention of Asthma (STOPPA) is to identify environmental (birth characteristics and early life) and genetic (including epigenetic) factors as determinants for asthmatic disease. Based on the Child and Adolescent Twin Study in Sweden (parental interview at 9 or 12 years, N~23,900) and an asthma and/or wheezing algorithm, we identified a sample of monozygotic (MZ) and dizygotic (DZ) same-sexed twin pairs. The twin pairs were identified as asthma concordant (ACC), asthma discordant (ADC) and healthy concordant (HCC). A sample of 9- to 14-year-old twins and their parents were invited to participate in a clinical examination. Background characteristics were collected in questionnaires and obtained from the National Health Registers. A clinical examination was performed to test lung function and capacity (spirometry with reversibility test and exhaled nitric oxide) and collect blood (serology and DNA), urine (metabolites), feces (microbiota) and saliva (cortisol). In total, 376 twin pairs (752 individual twins) completed the study, response rate 52%. All participating twins answered the questionnaire and >90% participated in lung function testing, blood and saliva sampling. This article describes the design, recruitment, data collection, measures, background characteristics as well as ongoing and planned analyses in STOPPA. Potential gains of the study include the identification of biomarkers, the emergence of candidates for drug development and new leads for prevention of asthma and allergic disease.NonePublishe

Validation of asthma and eczema in population-based Swedish drug and patient registers

Purpose: Validated measures of asthma and eczema at the population level remain a challenge. Our aim was to ascertain if register-based information on asthma/eczema medicat ion can function as a proxy for an asthma/eczema diagnosis and to validate register-based asthma diagnoses. Methods: Information was requested on all 0-45 year old individuals with reported asthma/eczema medication and/or diagnoses in the Swedish Prescribed Drug Register and National Patient Register, between July 2005 and December 2009 (N=250,691). Medical records for 1,952 randomly selected individuals were reviewed to estimate the proportion of individuals with 1) asthma/eczema medication that fulfilled p redefined criteria of asthma/eczema (positive predictive value, PPV); 2) a register-based asthma diagnosis verified as asthma by set criteria. Results: PPV for asthma by predefined criteria ranged between 0.75 (95% CI: 0.70-0.78) to 0.94 (95% CI: 0.91-0.96), depending on age-group. In pre-school children, PPV for asthma in combination with obstructive bronchitis was 0.87 (95% CI: 0.83-0.90) and PPV for eczema was estimated to 0.45 (95% CI: 0.38-0.51). Eighty percent of children 0-4.5 years and 99% of children >4.5-17 years with a register-based diagnosis of asthma were verified as asthmatics. Conclusion: Asthma medication is a suitable proxy for asthma in older children and adults; the same approach is insufficient for eczema. This validation study of two Swedish registers opens for future large nation-wide register-based studies on asthma.Swedish Research CouncilVetenskapsrådetALFManuscrip

Individual maternal and child exposure to antibiotics in hospital : a national population-based validation study

Aim: Exposure to antibiotics in early life may affect future health. Most antibiotics are prescribed in outpatient care, but inpatient exposure is also important. We estimated how specific diagnoses in hospitals corresponded to individual antibiotic exposure. Methods: All pregnant women and children from birth to five-years-of-age with infectious diseases and common inpatient diagnoses between July 2005 and November 2011were identified from the Swedish National Patient Register. Random samples of individuals from pre-defined groups were drawn and medical records received from the clinics were manually reviewed for antibiotics. Results: Medical records for 4,319 hospital visits were requested and 3,797 (88%) were received. A quarter (25%) of children diagnosed as premature had received antibiotics and in children from one to five-years-of-age, diagnoses associated with bacterial infections were more commonly treated with antibiotics (62.4-90.6%) than those associated with viruses (6.3-22.2%). Pregnant women who had undergone a Caesarean section were more likely to be treated with antibiotics than those who had had a vaginal delivery (40.1% versus 11.1%). Conclusions: This study defines the proportion of new mothers and young children who received individual antibiotic treatment for specific inpatient diagnoses in Sweden and provides a useful basis for future studies focusing on antibiotic use.Swedish Research Council, 2011-3060Swedish Initiative for Research on Microdata in the Social And Medical Sciences (SIMSAM), 80748301 and 340-2013- 5867Stockholm County Council (ALF)Swedish Heart Lung FoundationStrategic Research Program in Epidemiology at Karolinska InstitutetManuscrip

Antibiotics in fetal and early life and subsequent childhood asthma : nationwide population based study with sibling analysis

OBJECTIVE: To investigate the association between exposure to antibiotics in fetal and early life and asthma in childhood, with adjustment for confounding factors. DESIGN: Nationwide prospective population based cohort study, including sibling control design. SETTING: Swedish population identified from national demographic and health registers. PARTICIPANTS: 493,785 children born 2006-10; 180,894 of these were eligible for sibling analyses. MAIN OUTCOME MEASURE: Asthma defined as having both an asthma diagnosis and dispensed asthma drugs. The association between antibiotic exposure and asthma was investigated in the whole cohort with Cox proportional hazard regression. A stratified proportional hazards model conditional on sibling group was used to adjust for shared factors within families. Confounding by respiratory infections was assessed by investigating whether specific groups of antibiotics were associated with asthma. RESULTS: Antibiotic exposure in fetal life was associated with an increased risk of asthma in cohort analyses (hazard ratio 1.28, 95% confidence interval 1.25 to 1.32), but not in sibling analyses (0.99, 0.92 to 1.07). In cohort analyses, antibiotics used to treat respiratory infections in childhood were associated with a more pronounced increased risk of asthma (4.12, 3.78 to 4.50) than antibiotics used for urinary tract and skin infections (1.54, 1.24 to 1.92). In sibling analyses, the excess risks after exposure to antibiotics for respiratory infections decreased (2.36, 1.78 to 3.13) and disappeared for antibiotics for urinary tract and skin (0.85, 0.47 to 1.55). CONCLUSIONS: Previous positive associations between exposure to antibiotics in fetal and early life and subsequent childhood asthma could have been caused by confounding by shared familial factors, in addition to confounding by respiratory infections.NonePublishe

Fetal and early life antibiotics exposure and very early onset inflammatory bowel disease – a population-based study

Objective Earlier studies on antibiotics exposure and development of IBD (Crohn’s disease (CD) and ulcerative colitis (UC)) may have been biased by familial factors and gastroenteritis. We aimed to estimate the association between antibiotics during pregnancy or infantile age and very early onset (VEO) IBD. Design In this cohort study of 827 239 children born in Sweden between 2006 and 2013, we examined the link between exposure to systemic antibiotics and VEO-IBD (diagnosis <6 years of age), using Cox proportional hazard regression models. Information on antibiotics and IBD was retrieved from the nationwide population-based Swedish Prescribed Drug Register and the National Patient Register. We specifically examined potential confounding from parental IBD and gastroenteritis. Results Children exposed to antibiotics during pregnancy were at increased risk of IBD compared with general population controls (adjusted HR (aHR) 1.93; 95% CI 1.06 to 3.50). Corresponding aHRs were 2.48 (95% CI 1.01 to 6.08) for CD and 1.25 (95% CI 0.47 to 3.26) for UC, respectively. For antibiotics in infantile age, the aHR for IBD was 1.11 (95% CI 0.57 to 2.15); for CD 0.72 (95% CI 0.27 to 1.92) and 1.23 (95% CI 0.45 to 3.39) for UC. Excluding children with gastroenteritis 12 months prior to the first IBD diagnosis retained similar aHR for antibiotics during pregnancy and CD, while the association no longer remained significant for IBD. Conclusion We found that exposure to antibiotics during pregnancy, but not in infantile age, is associated with an increased risk of VEO-IBD regardless of gastroenteritis. The risk increase for exposure in pregnancy may be due to changes in the microbiota.Financial support was provided from the Swedish Research Council through the Swedish Initiative for Research on Microdata in the Social And Medical Sciences (SIMSAM) framework grant no 340-2013-5867, grants provided by the Stockholm County Council (ALF-projects), the Swedish Heart-Lung Foundation and the Swedish Asthma and Allergy Association’s Research Foundation.Accepte

Early exposure to dogs and farm animals and the risk of childhood asthma

IMPORTANCE: The association between early exposure to animals and childhood asthma is not clear, and previous studies have yielded contradictory results. OBJECTIVE: To determine whether exposure to dogs and farm animals confers a risk of asthma. DESIGN, SETTING AND PARTICIPANTS: In a nationwide cohort study, the association between early exposure to dogs and farm animals and the risk of asthma was evaluated and included all children born in Sweden from January 1, 2001, to December 31, 2010 (N = 1,011,051), using registry data on dog and farm registration, asthma medication, diagnosis, and confounders for parents and their children. The association was assessed as the odds ratio (OR) for a current diagnosis of asthma at age 6 years for school-aged children and as the hazard ratio (HR) for incident asthma at ages 1 to 5 years for preschool-aged children. Data were analyzed from January 1, 2007, to September 30, 2012. EXPOSURES: Living with a dog or farm animal. MAIN OUTCOMES AND MEASURES: Childhood asthma diagnosis and medication used. RESULTS: Of the 1,011,051 children born during the study period, 376,638 preschool-aged (53,460 [14.2%] exposed to dogs and 1729 [0.5%] exposed to farm animals) and 276,298 school-aged children (22,629 [8.2%] exposed to dogs and 958 [0.3%] exposed to farm animals) were included in the analyses. Of these, 18,799 children (5.0%) in the preschool-aged children's cohort experienced an asthmatic event before baseline, and 28,511 cases of asthma and 906,071 years at risk were recorded during follow-up (incidence rate, 3.1 cases per 1000 years at risk). In the school-aged children's cohort, 11,585 children (4.2%) experienced an asthmatic event during the seventh year of life. Dog exposure during the first year of life was associated with a decreased risk of asthma in school-aged children (OR, 0.87; 95% CI, 0.81-0.93) and in preschool-aged children 3 years or older (HR, 0.90; 95% CI, 0.83-0.99) but not in children younger than 3 years (HR, 1.03; 95% CI, 1.00-1.07). Results were comparable when analyzing only first-born children. Farm animal exposure was associated with a reduced risk of asthma in both school-aged children and preschool-aged children (OR, 0.48; 95% CI, 0.31-0.76, and HR, 0.69; 95% CI, 0.56-0.84), respectively. CONCLUSIONS AND RELEVANCE: In this study, the data support the hypothesis that exposure to dogs and farm animals during the first year of life reduces the risk of asthma in children at age 6 years. This information might be helpful in decision making for families and physicians on the appropriateness and timing of early animal exposure.NonePublishe

Fetal death after the introduction of COVID-19 mitigation measures in Sweden, Denmark and Norway: a registry-based study

It remains unclear whether the rate of fetal death has changed during the COVID-19 pandemic. We assessed the impact of COVID-19 mitigation measures on fetal death in Sweden (449,347 births), Denmark (290,857 pregnancies) and Norway (261,057 pregnancies) using robust population-based registry data. We used Cox regression to assess the impact of the implementation of pandemic mitigation measures on March 12th, 2020, on miscarriage (fetal loss before gestational week 22) and stillbirth (fetal loss after gestational week 22). A total of 11% of 551,914 pregnancies in Denmark and Norway ended in miscarriage, while the proportion of stillbirths among 937,174 births across the three countries was 0.3%. There was no difference in the risk of fetal death during the year following pandemic mitigation measures. For miscarriage, the combined hazard ratio (HR) for Norway and Denmark was 1.01 (95% CI 0.98, 1.03), and for stillbirth, the combined HR for all three countries was 0.99 (95% CI 0.89, 1.09). We observed a slightly decreased risk of miscarriage during the first 4 months, with an HR of 0.94 (95% CI 0.90, 0.99) after lockdown. In conclusion, the risk of fetal death did not change after the implementation of COVID-19 pandemic mitigation measures in the three Scandinavian countries