Early-life environment and the risk of eczema at 2 years-Meta-analyses of six Finnish birth cohorts

BACKGROUND

Urban-related nature exposures are suggested to contribute to the rising prevalence of allergic diseases despite little supporting evidence. Our aim was to evaluate the impact of 12 land cover classes and two greenness indices around homes at birth on the development of doctor-diagnosed eczema by the age of 2 years, and the influence of birth season.

METHODS

Data from 5085 children were obtained from six Finnish birth cohorts. Exposures were provided by the Coordination of Information on the Environment in three predefined grid sizes. Adjusted logistic regression was run in each cohort, and pooled effects across cohorts were estimated using fixed or random effect meta-analyses.

RESULTS

In meta-analyses, neither greenness indices (NDVI or VCDI, 250 m × 250 m grid size) nor residential or industrial/commercial areas were associated with eczema by age of 2 years. Coniferous forest (adjusted odds ratio 1.19; 95% confidence interval 1.01-1.39 for the middle and 1.16; 0.98-1.28 for the highest vs. lowest tertile) and mixed forest (1.21; 1.02-1.42 middle vs. lowest tertile) were associated with elevated eczema risk. Higher coverage with agricultural areas tended to associate with elevated eczema risk (1.20; 0.98-1.48 vs. none). In contrast, transport infrastructure was inversely associated with eczema (0.77; 0.65-0.91 highest vs. lowest tertile).

CONCLUSION

Greenness around the home during early childhood does not seem to protect from eczema. In contrast, nearby coniferous and mixed forests may increase eczema risk, as well as being born in spring close to forest or high-green areas.

Age and sex differences in the cortisol stress reactivity and recovery among infants exposed to prenatal psychological distress

BACKGROUND

Altered hypothalamic-pituitary-adrenal axis (HPA) functioning is one of the potential mechanisms bridging exposure to maternal prenatal psychological distress (PPD) and later risk for offspring psychiatric illness. Research on infant cortisol stress reactivity, on scarcely studied recovery and their associations with maternal PPD is needed to clarify these mechanisms. Knowledge on sex differences in prospective settings is largely lacking. We aimed at filling these gaps by building upon our previous report showing that exposure to maternal prenatal depressive and anxiety symptoms associates with slower cortisol recovery among 10-week-old female infants.

METHODS

In all, 363, 205 and 263 infants at 10 weeks, six and 14 months of age from the FinnBrain Birth Cohort Study participated in a stress test comprising of venipuncture and nasopharynx sampling. Five saliva cortisol samples were collected during each visit to measure cortisol reactivity and recovery. PPD was assessed from maternal self-reports for depressive, anxiety and pregnancy-related anxiety symptoms at gestational weeks 14, 24 and 34.

RESULTS

An 11% enhanced recovery among 14-month-old females was associated with higher depressive and anxiety symptoms (95% CI=1-23%) and pregnancy-related anxiety symptoms (2-21%). No alterations in the female cortisol reactivity or male cortisol stress responses were observed.

CONCLUSIONS

The opposite directions in the associations between the PPD exposure and infant cortisol recovery among 10-week-old and 14-month-old females suggest sex- and age-dependent associations between HPA axis functioning and PPD exposure among healthy infants. Follow-up is needed to characterize the impact of this altered negative feedback mechanism on later health.

Maternal prenatal psychological distress associates with offspring early-life wheezing - FinnBrain Birth Cohort

BACKGROUND

Exposure to prenatal maternal psychological distress may contribute to the development of childhood atopic disorders. Little is known about the importance of distress severity and its duration for the risk. Our aim was to investigate how chronic maternal depressive and anxiety symptoms across gestation influence the risk of wheezing and eczema at child age 24 months.

METHODS

The study population was drawn from the FinnBrain Birth Cohort Study, including 1305 mother-infant dyads followed across gestation until the child age of 24 months when the outcomes were mother-reported wheezing ever and doctor-diagnosed eczema. To investigate the risk of wheezing phenotypes, wheezing with and without eczema was separated. Maternal distress was assessed with the Edinburgh Postnatal Depression Scale for depressive and the Symptom Checklist-90 for anxiety symptoms three times during pregnancy, and the chronicity was demonstrated using symptom trajectories composed by latent growth mixture modeling.

RESULTS

Of the children, 219/1305 (17%) had wheezing ever and 285/1276 (22%) had eczema. Risk of wheezing ever was elevated with maternal consistently high depressive symptoms (adjusted odds ratio 2.74; 95% confidence interval 1.37-5.50) or moderate and increasing anxiety symptoms (1.94; 1.06-3.54, respectively). Similarly, wheezing without eczema was associated with consistently high depressive (3.60; 1.63-7.94, respectively) and moderate and increasing anxiety symptoms (2.43; 1.21-4.91, respectively).

CONCLUSIONS

Maternal chronic psychological distress across gestation was associated with toddler wheezing and especially wheezing without other atopic features (eczema). This finding supports the theory of intrauterine programming effect by maternal psychological distress on offspring immune system and respiratory morbidity.

Prevalence and evolution of snoring and the associated factors in two-year-old children

OBJECTIVES

To evaluate the prevalence and persistence of snoring during the first two years of life in two Finnish birth cohorts and to assess the associated factors.

STUDY DESIGN

The study population comprised 947 children from the CHILD-SLEEP (CS) and 1393 children from the FinnBrain (FB) birth cohorts. Questionnaires were provided to both parents when the child was 24 months of age. The questionnaire consisted of parts concerning the child's sleep and environmental factors.

RESULTS

The combined prevalence of habitual snoring in the two birth cohorts at the age of 24 months was 2.3% (95% CI 1.5-3.1), which is markedly lower than reported previously. Children suffering from recurrent infections (CS odds ratio (OR) 3.9, 95% CI 1.2-12.5) or asthma (FB OR 4.3, 1.4-13.5) snored habitually more often. Both the mother's (CS OR 3.2, 1.2-9.0) and father's (CS OR 3.4, 1.4-8.0) snoring every night added to the risk of the child snoring. In the multivariate models, parental snoring (CS adjusted odds ratio (OR_a) 2.8, 1.1-6.8), the mother's lower level of education (CS OR_a 2.9, 1.2-7.5, FB OR_a 2.1, 1.0-4.5), and the mother's lower monthly income (FB OR_a 2.9, 1.3-6.3) associated with the child's habitual snoring.

CONCLUSIONS

The prevalence of habitual snoring in two Finnish birth cohorts is lower than reported previously. The independent risk factors for habitual snoring at the age of two years were the parents' snoring and the mother's low income and low education.

Interactions of genetic variants and prenatal stress in relation to the risk for recurrent respiratory infections in children

Genetic variants may predispose children to recurrent respiratory infections (RRIs) but studies on genotype-environment interaction are rare. We hypothesized that the risk for RRIs is elevated in children with innate immune gene variants, and that prenatal exposure to maternal psychological distress further increases the risk. In a birth cohort, children with RRIs (n = 96) were identified by the age of 24 months and compared with the remaining cohort children (n = 894). The risk for RRIs in children with preselected genetic variants and the interaction between maternal distress during pregnancy and child genotype were assessed with logistic regression. The IL6 minor allele G was associated with elevated risk for RRIs (OR 1.55; 95% CI 1.14-2.12). Overall, there was no interaction between maternal psychological distress and child genotype. Exploratory analyses showed that, the association between the variant type of IL6 and the risk for RRIs was dependent on prenatal exposure to maternal psychological distress in males (OR 1.96; 95% CI 1.04-3.67). Our study didn't find genotype-environment interaction between prenatal maternal distress and child genotype. Exploratory analyses suggest sex differences in gene-environment interaction related to susceptibility to RRIs.

Associations Between IFI44L Gene Variants and Rates of Respiratory Tract Infections During Early Childhood

Background

Genetic heterogeneity in type I interferon (IFN)–related gene IFI44L may account for variable susceptibility to respiratory tract infections (RTIs) in children.

Methods

In 2 prospective, population-based birth cohorts, the STEPS Study and the FinnBrain Birth Cohort Study, IFI44L genotypes for rs273259 and rs1333969 were determined in relation to the development of RTIs until 1 or 2 years of age, respectively. At age 3 months, whole-blood transcriptional profiles were analyzed and nasal samples were tested for respiratory viruses in a subset of children.

Results

In the STEPS Study (n = 1135), IFI44L minor/minor gene variants were associated with lower rates of acute otitis media episodes (adjusted incidence rate ratio, 0.77 [95% confidence interval, .61–.96] for rs273259 and 0.74 [.55–.99] for rs1333969) and courses of antibiotics for RTIs (0.76 [.62–.95] and 0.73 [.56–.97], respectively. In the FinnBrain cohort (n = 971), IFI44L variants were associated with lower rates of RTIs and courses of antibiotics for RTIs. In respiratory virus–positive 3-month-old children, IFI44L gene variants were associated with decreased expression levels of IFI44L and several other IFN-related genes.

Conclusions

Variant forms of IFI44L gene were protective against early-childhood RTIs or acute otitis media, and they attenuated IFN pathway activation by respiratory viruses.

Prenatal maternal distress associates with a blunted cortisol response in rhinovirus-positive infants

INTRODUCTION

Prenatal exposure to maternal psychological distress (PD) may have programming effects on the fetus/infant hypothalamic-pituitary-adrenal (HPA) axis and subsequently on the development of the fetus' immune function. Therefore, our aim was to study whether prenatal exposure to PD is related to early infant HPA axis reactivity in the context of a subclinical rhinovirus infection that challenges infants HPA axis postnatally.

METHODS

This study included 336 10-week-old infants from the nested case control Focus Cohort of the FinnBrain Birth Cohort Study. The outcome was infant HPA axis reactivity in a stress test. The acute stressor comprised of pediatric examination with venipuncture and nasal swabs for virus assessment. Saliva cortisol samples were collected at 5 time points: baseline, 0, 15, 25 and 35 min after the stressor. HPA axis reactivity was defined by the cumulative post-stressor cortisol concentration.

RESULTS

HPA axis reactivity was blunted in the PD/rhinovirus + group compared to the average of control/rhinovirus+, PD/rhinovirus-, and control/rhinovirus- groups (difference: 14.7 ln [nmol/L] × min, 95% confidence interval 3.8-25.6, p =  .008). HPA axis reactivity was significantly blunted only in boys with rhinovirus detected when separately tested for boys and girls (p =  .04).

CONCLUSION

Our finding of PD-exposed rhinovirus-positive infants having blunted cortisol secretion gives rise to a hypothesis that maternal PD during pregnancy influences infant HPA axis functioning and the functioning of the immune system. Future studies are needed to test whether this suppression of the HPA axis that co-occurs with rhinovirus infection associates with later disease development (e.g., asthma).

Prenatal Maternal Psychological Distress and Offspring Risk for Recurrent Respiratory Infections

OBJECTIVE

To assess the relation between maternal prenatal psychological distress, comprising depression and anxiety symptoms and relationship quality, and the risk of recurrent respiratory infections (RRIs) in children up to 2 years of age. Children with RRIs frequently use health care services and antibiotics. Prenatal maternal psychological distress can be one, previously unidentified risk factor for RRIs.

STUDY DESIGN

The study population was drawn from a population-based pregnancy cohort in Finland (www.finnbrain.fi). Children with RRIs (n = 204) and a comparison group (n = 1014) were identified by maternal reports at the child age of 12 or 24 months. The Edinburgh Postnatal Depression Scale, Symptom Checklist-90 anxiety subscale, the Pregnancy-Related Anxiety Questionnaire-Revised 2, and the Revised Dyadic Adjustment Scale were used to assess maternal symptoms and parental relationship quality at 34 weeks of gestation. Adjustment for maternal postnatal depressive and anxiety symptoms was performed.

RESULTS

Maternal prenatal Edinburgh Postnatal Depression Scale (OR, 1.24; 95% CI, 1.08-1.44), Symptom Checklist-90/Anxiety (OR, 1.40; 95% CI, 1.01-1.76), Pregnancy-Related Anxiety Questionnaire-Revised 2 (OR, 1.28; 95% CI, 1.11-1.47), and Revised Dyadic Adjustment Scale (OR, 1.32; 95% CI, 1.01-1.58) total sum scores were associated with child RRIs by the age of 24 months. Greater number of siblings, shorter duration of breastfeeding, and the level of maternal education were also identified as risk factors for child RRIs.

CONCLUSIONS

Maternal prenatal psychological distress is linked with a higher risk for child RRIs.