Hein Stigum

Folic acid supplements in pregnancy and early childhood respiratory health

Background: Folate supplementation is recommended for pregnant women to reduce the risk of congenital malformations. Maternal intake of folate supplements during pregnancy might also influence childhood immune phenotypes via epigenetic mechanisms. Objective: To investigate the relationship between folate supplements in pregnancy and risk of lower respiratory tract infections and wheeze in children up to 18 months of age. Methods: In the Norwegian Mother and Child Cohort Study, questionnaire data collected at several time points during pregnancy and after birth on 32 077 children born between 2000 and 2005 were used to assess the effects of folate supplements during pregnancy on respiratory outcomes up to 18 months of age, while accounting for other supplements in pregnancy and supplementation in infancy. Results: Folate supplements in the first trimester were associated with increased risk of wheeze and respiratory tract infections up to 18 months of age. Adjusting for exposure later in pregnancy and in infancy, the relative risk for wheeze for children exposed to folic acid supplements in the first trimester was 1.06 (95% CI 1.03 to 1.10), the relative risk for lower respiratory tract infections was 1.09 (95% CI 1.02 to 1.15) and the relative risk for hospitalisations for lower respiratory tract infections was 1.24 (95% CI 1.09 to 1.41). Conclusions: Folic acid supplements in pregnancy were associated with a slightly increased risk of wheeze and lower respiratory tract infections up to 18 months of age. The results suggest that methyl donors in the maternal diet during pregnancy may influence respiratory health in children consistent with epigenetic mechanisms.

Birth weight and prenatal exposure to polychlorinated biphenyls (PCBs) and dichlorodiphenyldichloroethylene (DDE): A meta-analysis within 12 European birth cohorts

Objectives: Exposure to high concentrations of persistent organochlorines may cause fetal toxicity, but the evidence at low exposure levels is limited. Large studies with substantial exposure contrasts and appropriate exposure assessment are warranted. Within the framework of the EU (European Union) ENRIECO (ENvironmental Health RIsks in European Birth Cohorts) and EU OBELIX (OBesogenic Endocrine disrupting chemicals: LInking prenatal eXposure to the development of obesity later in life) projects, we examined the hypothesis that the combination of polychlorinated biphenyls (PCBs) and dichlorodiphenyldichloroethylene (DDE) adversely affects birth weight. Methods: We used maternal and cord blood and breast milk samples of 7,990 women enrolled in 15 study populations from 12 European birth cohorts from 1990 through 2008. Using identical variable definitions, we performed for each cohort linear regression of birth weight on estimates of cord serum concentration of PCB-153 and p,p´-DDE adjusted for gestational age and a priori selected covariates. We obtained summary estimates by meta-analysis and performed analyses of interactions. Results: The median concentration of cord serum PCB-153 was 140 ng/L (range of cohort medians 20–484 ng/L) and that of p,p´-DDE was 528 ng/L (range of cohort medians 50–1,208 ng/L). Birth weight decreased with increasing cord serum concentration of PCB-153 after adjustment for potential confounders in 12 of 15 study populations. The meta-analysis including all cohorts indicated a birth weight decline of 150 g [95% confidence interval (CI): –250, –50 g] per 1-µg/L increase in PCB-153, an exposure contrast that is close to the range of exposures across the cohorts. A 1-µg/L increase in p,p´-DDE was associated with a 7-g decrease in birth weight (95% CI: –18, 4 g). Conclusions: The findings suggest that low-level exposure to PCB (or correlated exposures) impairs fetal growth, but that exposure to p,p´-DDE does not. The study adds to mounting evidence that low-level exposure to PCBs is inversely associated with fetal growth.

Recurrent pain in children, socio-economic factors and accumulation in families.

The aim of this study was to estimate the prevalence of parent-reported pain among children in the Nordic countries in 1996, and to describe the association between recurrent pain in children and parental socio-economic factors. We also wanted to estimate the association between parental pain and childhood pain and co-occurrence of different pain patterns in the same child. Data were obtained from a cross-sectional survey on childrens health and well-being in the Nordic countries in 1996. About 10, 000 children aged 2–17 years of age were selected from population registries. Mean response rate was 68%. We selected the cases ≥7 years where the respondent was the childs biological mother or father, yielding a total of 6230 subjects. The adjusted analyses were performed using logistic regression in SPSS. The total prevalence of headache, abdominal pain and back pain among children 7–17 years of age was 14.9, 8.3 and 4.7%, respectively. The most common pain combination was headache and abdominal pain. Pain was most frequent among girls. The prevalence was slightly higher in low educated or low-income families compared to those of high status. Children living in low educated, low-income, worker families had approximately a 1.4-fold odds of having pain. There was a strong association between the different pain conditions, and between pain and other forms of distress in the same child. A site-specific association between parental and child pain was also shown, but we assume that this might have been mediated through subjective (information) bias.

Use of Pornography in Traditional Media and on the Internet in Norway

We described the use of pornography in Norway, including how many people have used pornographic magazines, films, and internet sites and to what extent those who watch pornography on the internet also use it as an arena for erotic chatting. The data stem from a survey on sexual behavior among a random sample of 10,000 Norwegians between 18 and 49 years. The response rate was 34%. A total of 82% reported having read pornographic magazines, 84% had seen pornographic films, and 34% had examined pornography on the internet. Statistically significantly more men than women reported use of pornography. There was a 20% difference between men and women in use of magazines and films. Among those exposed to pornography on the internet during the past year, 14% had participated in erotic chatting. Gay/bisexual men and lesbian/bisexual women reported higher use of pornography than straight men and women. Gender was the most significant variable for the prediction of use of pornography. Level of education predicted exposure to pornography on the internet, in magazines, and in films. Younger individuals were more likely to utilize the internet both for viewing pornographic material and for chatting.

Low iron stores are related to higher blood concentrations of manganese, cobalt and cadmium in non-smoking, Norwegian women in the HUNT 2 study

Low iron (Fe) stores may influence absorption or transport of divalent metals in blood. To obtain more knowledge about such associations, the divalent metal ions cadmium (Cd), manganese (Mn), cobalt (Co), copper (Cu), zinc (Zn) and lead (Pb) and parameters of Fe metabolism (serum ferritin, haemoglobin (Hb) and transferrin) were investigated in 448 healthy, menstruating non-smoking women, age 20-55 years (mean 38 years), participating in the Norwegian HUNT 2 study. The study population was stratified for serum ferritin: 257 were iron-depleted (serum ferritin < 12 microg/L) and 84 had iron deficiency anaemia (serum ferritin < 12 microg/L and Hb < 120 g/L). The low ferritin group had increased blood concentrations of Mn, Co and Cd but normal concentrations of Cu, Zn and Pb. In multiple regression models, ferritin emerged as the main determinant of Mn, Co and Cd (p < 0.001), while no significant associations with Cu, Zn and Pb were found. Adjusted r(2) for the models were 0.28, 0.48 and 0.34, respectively. Strong positive associations between blood concentrations of Mn, Co and Cd were observed, also when controlled for their common association with ferritin. Apart from these associations, the models showed no significant interactions between the six divalent metals studied. Very mild anaemia (110 < or = Hb < 120 g/L) did not seem to have any effect independent of low ferritin. Approximately 26% of the women with iron deficiency anaemia had high concentrations of all of Mn, Co and Cd as opposed to 2.3% of iron-replete subjects. The results confirm that low serum ferritin may have an impact on body kinetics of certain divalent metal ions, but not all. Only a fraction of women with low iron status exhibited an increased blood concentration of divalent metals, providing indication of complexities in the bodys handling of these metals.

Changes in Concentrations of Perfluorinated Compounds, Polybrominated Diphenyl Ethers, and Polychlorinated Biphenyls in Norwegian Breast-Milk during Twelve Months of Lactation

At present, scientific knowledge on depuration rates of persistent organic pollutants (POPs) is limited and the previous assumptions of considerable reduction of body burdens through breast-feeding have recently been challenged. We therefore studied elimination rates of important POPs in nine Norwegian primiparous mothers and one mother breast-feeding her second child by collecting breast-milk samples (n = 70) monthly from about two weeks to up to twelve months after birth. Perfluorinated compounds (PFCs), polybrominated diphenyl ethers (PBDEs), hexabromocyclododecane (HBCD), and polychlorinated biphenyls (PCBs) were determined in the breast-milk samples. Linear mixed effect models were established for selected compounds, and significant decreases in the range of 1.2-4.7% in breast-milk concentrations per month were observed for a wide range of PCBs and PBDEs. For the first time, depuration rates for perfluorooctylsulfonate (PFOS) and perfluorooctanoic acid (PFOA) are presented, being 3.8 and 7.8% per month, respectively (p < 0.05). The relative amount of the branched PFOS isomers in the breast-milk samples was 18% on average (range 6-36%, RSD 30%). There were no significant differences in isomer pattern between the mothers, or changes during the lactation period. After a year of nursing the breast-milk concentrations of PFCs, PBDEs, and PCBs were reduced by 15-94%.

Parent-Offspring Body Mass Index Associations in the Norwegian Mother and Child Cohort Study: A Family-based Approach to Studying the Role of the Intrauterine Environment in Childhood Adiposity

In the present study, the authors investigated the role of the intrauterine environment in childhood adiposity by comparing the maternal-offspring body mass index (BMI) association with the paternal-offspring BMI association when the offspring were 3 years of age, using parental prepregnancy BMI (measured as weight in kilograms divided by height in meters squared). The parent-offspring trios (n = 29,216) were recruited during pregnancy from 2001 to 2008 into the Norwegian Mother and Child Cohort Study conducted by The Norwegian Institute of Public Health. Data from self-administered questionnaires were used in linear regression analyses. Crude analyses showed similar parental-offspring BMI associations; the mean difference in offspring BMI was 0.15 (95% confidence interval: 0.13, 0.16) per each 1-standard-deviation increase in maternal BMI and 0.15 (95% confidence interval: 0.13, 0.17) per each 1-standard-deviation increase in paternal BMI. After all adjustments, the mean difference in offspring BMI per each 1-standard-deviation increment of maternal BMI was 0.12, and the mean difference in offspring BMI per each 1-standard-deviation increment of paternal BMI was 0.13. There was no strong support for heterogeneity between the associations (P > 0.6). In conclusion, results from the present large population-based study showed similar parental-offspring BMI associations when the offspring were 3 years of age, which indicates that the maternal-offspring association may be explained by shared familial (environmental and genetic) risk factors rather than by the intrauterine environment.

Delivery by Cesarean Section and Early Childhood Respiratory Symptoms and Disorders The Norwegian Mother and Child Cohort Study

Studies have indicated that children delivered by cesarean section are at an increased risk of developing wheezing and asthma. This could be the result of an altered immune system development due to delayed gut colonization or of increased neonatal respiratory morbidity. The authors examined the associations between delivery by cesarean section and the development of wheezing, asthma, and recurrent lower respiratory tract infections in children up to 36 months of age among 37,171 children in the Norwegian Mother and Child Cohort Study. Generalized linear models were used in the multivariable analysis. Children delivered by cesarean section had an increased likelihood of current asthma at 36 months of age (relative risk = 1.17, 95% confidence interval: 1.03, 1.32), and the association was stronger among children of nonatopic mothers (relative risk = 1.33, 95% confidence interval: 1.12, 1.58). No increased risk of wheezing or recurrent lower respiratory tract infections was seen among children delivered by cesarean section. Findings were similar among children delivered by acute and elective cesarean section. In conclusion, children delivered by cesarean section may have an increased risk of current asthma at 36 months, but residual confounding cannot be excluded. In future prospective studies, investigators should reexamine this association in different age groups.

The association between self-reported physical activity and prevalence of depression and anxiety disorder in long-term survivors of testicular cancer and men in a general population sample

Goals of workPhysical activity is claimed to have a beneficial influence on a person’s mental health, though its impact may be different in cancer patients and individuals in the general population. The objective of this cross-sectional study was (1) to estimate the associations between the level of self-reported physical activity as a lifestyle factor (LPA) and the prevalence of depression and anxiety disorder in testicular cancer survivors (TCSs) and in men of similar age from the general population (GenPop), and (2) to examine whether these associations differ in the two groups.Patients and methodA total of 1260 TCSs and 20,207 men from the GenPop completed a questionnaire that assessed LPA, and depression and anxiety disorder on the Hospital Anxiety and Depression Scale (HADS).Main resultsThe prevalence of HADS-defined depression was lower among those who were physically active than in those who were physically inactive (TCSs 9% vs 17%, P<0.001; GenPop 8% vs 15%, P<0.001). Among physically inactive TCSs there was a trend towards higher a prevalence of HADS-defined anxiety disorder compared to physically active TCSs (P=0.07). In the GenPop this difference was statistically significant (P<0.001). Multivariate analysis confirmed the association between LPA and HADS-defined depression in both the TCSs [adjusted odds ratio (aOR)=0.56; 95% confidence interval (CI) (0.31, 1.02)] and the GenPop [aOR=0.58; 95% CI (0.51, 0.65)], but not the association between LPA and HADS-defined anxiety disorder. The associations between LPA and HADS-defined depression and HADS-defined anxiety disorder did not differ between the TCSs and the GenPop.ConclusionIn both the TCSs and the GenPop, the prevalence of HADS-defined depression was higher among those who were physically inactive than among those who were physically active, with no intergroup difference. There was no association between LPA and prevalence of HADS-defined anxiety disorder in either of the groups after adjusting for background variables. Prospective studies are needed to allow causal inferences to be drawn.

Maternal obesity in pregnancy and respiratory health in early childhood

Obesity is associated with systemic inflammation, immunological changes, increased risk of respiratory infections and chronic respiratory illness. Maternal obesity in pregnancy increases the risk of pregnancy complications, caesarean sections and adverse birth outcomes, which have in turn been associated with respiratory illness in children. To our knowledge, the possible influence of maternal obesity in pregnancy on respiratory illness in early childhood beyond the newborn period has not been explored. We examined the relationship between a high maternal body mass index (BMI) in pregnancy and lower respiratory tract infections and wheeze up to 18 months of age in the Norwegian Mother and Child Study (MoBa), a population-based cohort study that includes 100,000 pregnant women, conducted at the Norwegian Institute of Public Health. We analysed data from the first 33 192 children, born between 1999 and 2005. In unadjusted analyses maternal obesity in pregnancy was related to both respiratory infections and wheeze in the children. In multivariable analyses, only an effect on wheeze remained. The risk of wheeze increased linearly with maternal BMI in pregnancy, and was 3.3% higher [95% CI 1.2, 5.3] for children with mothers who were obese during pregnancy, than for children of mothers with normal BMI. This effect was not mediated through obesity-related pregnancy complications, low birthweight, preterm birth or caesarean section.