Marin Strøm

Intake of artificially sweetened soft drinks and risk of preterm delivery: a prospective cohort study in 59,334 Danish pregnant women

BACKGROUND Sugar-sweetened soft drinks have been linked to a number of adverse health outcomes such as high weight gain. Therefore, artificially sweetened soft drinks are often promoted as an alternative. However, the safety of artificial sweeteners has been disputed, and consequences of high intakes of artificial sweeteners for pregnant women have been minimally addressed. OBJECTIVE We examined the association between intakes of sugar-sweetened and artificially sweetened soft drinks and preterm delivery. DESIGN We conducted prospective cohort analyses of 59,334 women from the Danish National Birth Cohort (1996-2002). Soft drink intake was assessed in midpregnancy by using a food-frequency questionnaire. Preterm delivery ( lt 37 wk) was the primary outcome measure. Covariate information was assessed by telephone interviews. RESULTS There was an association between intake of artificially sweetened carbonated and noncarbonated soft drinks and an increased risk of preterm delivery (P for trend: le 0.001, both variables). In comparison with women with no intake of artificially sweetened carbonated soft drinks, the adjusted odds ratio for women who consumed ge 1 serving of artificially sweetened carbonated soft drinks/d was 1.38 (95% CI: 1.15, 1.65). The corresponding odds ratio for women who consumed ge 4 servings of artificially sweetened carbonated soft drinks/d was 1.78 (95% CI: 1.19, 2.66). The association was observed for normal-weight and overweight women. A stronger increase in risk was observed for early preterm and moderately preterm delivery than with late-preterm delivery. No association was observed for sugar-sweetened carbonated soft drinks (P for trend: 0.29) or for sugar-sweetened noncarbonated soft drinks (P for trend: 0.93). CONCLUSIONS Daily intake of artificially sweetened soft drinks may increase the risk of preterm delivery. Further studies are needed to reject or confirm these findings.

Fish and long-chain n−3 polyunsaturated fatty acid intakes during pregnancy and risk of postpartum depression: a prospective study based on a large national birth cohort

BACKGROUND Mothers may be reluctant to receive medical treatment of postpartum depression (PPD), despite the detrimental consequences the disorder can impose on mother and child. Research on alternative methods of prevention and treatment of PPD is warranted. Previous studies have suggested that long-chain n-3 polyunsaturated fatty acids (PUFAs) might have a beneficial effect on depression. OBJECTIVE The objective was to explore the association between intake of fish and n-3 PUFAs during pregnancy and PPD in the Danish National Birth Cohort (DNBC). DESIGN Exposure information from the DNBC was linked to the Danish patient and prescription registries for data on clinically identified cases of depression up to 1 y postpartum. Intake of fish and n-3 PUFAs was assessed in midpregnancy with a food-frequency questionnaire. Admission to the hospital for PPD (PPD-admission) and prescription of antidepressants (PPD-prescription) were treated as separate outcomes. A total of 54,202 women were included in the present study sample. RESULTS Rates of depression were 0.3% (PPD-admission) and 1.6% (PPD-prescription). No association was observed between fish intake and risk of PPD-admission [crude odds ratio of 1.01 (95% CI: 0.52, 1.97) and adjusted odds ratio of 0.82 (95% CI: 0.42, 1.64)], whereas a higher risk of PPD-prescription was found for the lowest compared with the highest fish intake group [crude odds ratio of 1.61 (95% CI: 1.26, 2.06) and adjusted odds ratio of 1.46 (95% CI: 1.12, 1.90)]. No association was observed with respect to n-3 PUFA intake. CONCLUSION Overall, our data from a large prospective cohort linked with high-quality registers showed little evidence to support an association between intake of fish or n-3 PUFAs and PPD.

Does leisure time physical activity in early pregnancy protect against pre‐eclampsia? Prospective cohort in Danish women

Objective  To examine the association between physical activity in early pregnancy and risk of pre‐eclampsia.

Fish intake during pregnancy, fetal growth, and gestational length in 19 European birth cohort studies.

BACKGROUND Fish is a rich source of essential nutrients for fetal development, but in contrast, it is also a well-known route of exposure to environmental pollutants. OBJECTIVE We assessed whether fish intake during pregnancy is associated with fetal growth and the length of gestation in a panel of European birth cohort studies. DESIGN The study sample of 151,880 mother-child pairs was derived from 19 population-based European birth cohort studies. Individual data from cohorts were pooled and harmonized. Adjusted cohort-specific effect estimates were combined by using a random- and fixed-effects meta-analysis. RESULTS Women who ate fish >1 time/wk during pregnancy had lower risk of preterm birth than did women who rarely ate fish (≤ 1 time/wk); the adjusted RR of fish intake >1 but <3 times/wk was 0.87 (95% CI: 0.82, 0.92), and for intake ≥ 3 times/wk, the adjusted RR was 0.89 (95% CI: 0.84, 0.96). Women with a higher intake of fish during pregnancy gave birth to neonates with a higher birth weight by 8.9 g (95% CI: 3.3, 14.6 g) for >1 but <3 times/wk and 15.2 g (95% CI: 8.9, 21.5 g) for ≥ 3 times/wk independent of gestational age. The association was greater in smokers and in overweight or obese women. Findings were consistent across cohorts. CONCLUSION This large, international study indicates that moderate fish intake during pregnancy is associated with lower risk of preterm birth and a small but significant increase in birth weight.

Vitamin D Status during Pregnancy and the Risk of Subsequent Postpartum Depression: A Case-Control Study

Epidemiological studies have provided evidence of an association between vitamin D insufficiency and depression and other mood disorders, and a role for vitamin D in various brain functions has been suggested. We hypothesized that low vitamin D status during pregnancy might increase the risk of postpartum depression (PPD). The objective of the study was thus to determine whether low vitamin D status during pregnancy was associated with postpartum depression. In a case-control study nested in the Danish National Birth Cohort, we measured late pregnancy serum concentrations of 25[OH]D3 in 605 women with PPD and 875 controls. Odds ratios [OR) for PPD were calculated for six levels of 25[OH]D3. Overall, we found no association between vitamin D concentrations and risk of PPD (p = 0.08). Compared with women with vitamin D concentrations between 50 and 79 nmol/L, the adjusted odds ratios for PPD were 1.35 (95% CI: 0.64; 2.85), 0.83 (CI: 0.50; 1.39) and 1.13 (CI: 0.84; 1.51) among women with vitamin D concentrations < 15 nmol/L, 15–24 nmol/L and 25–49 nmol/L, respectively, and 1.53 (CI: 1.04; 2.26) and 1.89 (CI: 1.06; 3.37) among women with vitamin D concentrations of 80–99 nmol/L and ≥ 100 nmol/L, respectively. In an additional analysis among women with sufficient vitamin D (≥ 50 nmol/L), we observed a significant positive association between vitamin D concentrations and PPD. Our results did not support an association between low maternal vitamin D concentrations during pregnancy and risk of PPD. Instead, an increased risk of PPD was found among women with the highest vitamin D concentrations.

Fish intake during pregnancy and the risk of child asthma and allergic rhinitis -longitudinal evidence from the Danish National Birth Cohort

Maternal fish intake during pregnancy may influence the risk of child asthma and allergic rhinitis, yet evidence is conflicting on its association with these outcomes. We examined the associations of maternal fish intake during pregnancy with child asthma and allergic rhinitis. Mothers in the Danish National Birth Cohort (n 28 936) reported their fish intake at 12 and 30 weeks of gestation. Using multivariate logistic regression, we examined the associations of fish intake with child wheeze, asthma and rhinitis assessed at several time points: ever wheeze, recurrent wheeze (>3 episodes), ever asthma and allergic rhinitis, and current asthma, assessed at 18 months (n approximately 22,000) and 7 years (n approximately 17,000) using self-report and registry data on hospitalisations and prescribed medications. Compared with consistently high fish intake during pregnancy (fish as a sandwich or hot meal > or equal to 2-3 times/week), never eating fish was associated with a higher risk of child asthma diagnosis at 18 months (OR 1·30, 95% CI 1·05, 1·63, P=0·02), and ever asthma by hospitalisation (OR 1·46, 95% CI 0·99, 2·13, P=0·05) and medication prescription (OR 1·37, 95% CI 1·10, 1·71, P=0·01). A dose-response was present for asthma at 18 months only (P for trend=0·001). We found no associations with wheeze or recurrent wheeze at 18 months or with allergic rhinitis. The results suggest that high (v. no) maternal fish intake during pregnancy is protective against both early and ever asthma in 7-year-old children.

A comparison of three methods to measure asthma in epidemiologic studies: results from the Danish National Birth Cohort.

Asthma is a heterogeneous outcome and how the condition should be measured to best capture clinically relevant disease in epidemiologic studies remains unclear. We compared three methods of measuring asthma in the Danish National Birth Cohort (n>50.000). When the children were 7 years old, the prevalence of asthma was estimated from a self-administered questionnaire using parental report of doctor diagnoses, ICD-10 diagnoses from a population-based hospitalization registry, and data on anti-asthmatic medication from a population-based prescription registry. We assessed the agreement between the methods using kappa statistics. Highest prevalence of asthma was found using the prescription registry (32.2%) followed by the self-report (12.0%) and the hospitalization registry (6.6%). We found a substantial non-overlap between the methods (kappa = 0.21–0.38). When all three methods were combined the asthma prevalence was 3.6%. In conclusion, self-reported asthma, ICD-10 diagnoses from a hospitalization registry and data on anti-asthmatic medication use from a prescription registry lead to different prevalences of asthma in the same cohort of children. The non-overlap between the methods may be due to different abilities of the methods to identify cases with different phenotypes, in which case they should be treated as separate outcomes in future aetiological studies.

Vitamin D Measured in Maternal Serum and Offspring Neurodevelopmental Outcomes: A Prospective Study with Long-Term Follow-Up

Background: Vitamin D is obtained from dietary sources and synthesized in the skin during exposure to ultraviolet B radiation in sunlight. During pregnancy, vitamin D is transported from mother to fetus through the placenta in the form of 25-hydroxyvitamin D [25(OH)D]. There is evidence that vitamin D influences neuronal differentiation, endocrine functions, and fetal brain growth. Animal studies indicate alterations in the offspring brain as a consequence of vitamin D deficiency during pregnancy. In humans, maternal vitamin D insufficiency has been linked to impaired child language development. Using data from a prebirth cohort with up to 22 years of follow-up, we examined the association of vitamin D status with proxies of offspring neurodevelopmental outcomes. During 1988-1989, pregnant women were recruited for the DaFO88 cohort (n = 965) in Aarhus, Denmark. Maternal concentrations of 25(OH)D were quantified in serum from week 30 of gestation via the LC-MS/MS method (n = 850). Offspring were followed up through national registries until the age of 22 years. We evaluated the association of the maternal concentration of 25(OH)D with offspring neurodevelopmental outcomes defined as first admission diagnosis or prescription of medication for (1) ADHD, (2) depression, and (3) scholastic achievement based on the mean grade on standardized written examinations in the 9th grade (final exams after 10 years of compulsory school in Denmark). Key Messages: Maternal concentrations of 25(OH)D were higher compared to current levels (median 76 nmol/l; 5th to 95th percentiles 23-152). There was a direct association between maternal vitamin D status and offspring depression (ptrend = 0.01); for ADHD there was no association. Scholastic achievement was slightly higher for offspring of mothers with a vitamin D status in the range of >50-125 nmol/l, but this nonlinear association was not statistically significant. Conclusions: Our analyses based on biomarker measurement of 25(OH)D from a cohort of 850 pregnant women combined with long-term follow-up showed no support for a beneficial fetal programming effect of vitamin D status with regard to behavioral and affective disorders and scholastic achievement.

Development and Validation of a Vitamin D Status Prediction Model in Danish Pregnant Women: A Study of the Danish National Birth Cohort

Vitamin D has been hypothesized to reduce risk of pregnancy complications such as preeclampsia, gestational diabetes mellitus, and preterm delivery. However, many of these outcomes are rare and require a large sample size to study, representing a challenge for cohorts with a limited number of preserved samples. The aims of this study were to (1) identify predictors of serum 25-hydroxy-vitamin D (25(OH)D) among pregnant women in a subsample (N = 1494) of the Danish National Birth Cohort (DNBC) and (2) develop and validate a score predicting 25(OH)D-status in order to explore associations between vitamin D and maternal and offspring health outcomes in the DNBC. In our study sample, 42.3% of the population had deficient levels of vitamin D (<50 nmol/L 25(OH)D) and average levels of 25(OH)D-status were 56.7(s.d. 24.6) nmol/L. A prediction model consisting of intake of vitamin D from diet and supplements, outdoor physical activity, tanning bed use, smoking, and month of blood draw explained 40.1% of the variance in 25(OH)D and mean measured 25(OH)D-level increased linearly by decile of predicted 25(OH)D-score. In total 32.2% of the women were placed in the same quintile by both measured and predicted 25(OH)D-values and 69.9% were placed in the same or adjacent quintile by both methods. Cohens weighted kappa coefficient (Κ = 0.3) reflected fair agreement between measured 25(OH)D-levels and predicted 25(OH)D-score. These results are comparable to other settings in which vitamin D scores have shown similar associations with disease outcomes as measured 25(OH)D-levels. Our findings suggest that predicted 25(OH)D-scores may be a useful alternative to measured 25(OH)D for examining associations between vitamin D and disease outcomes in the DNBC cohort, but cannot substitute for measured 25(OH)D-levels for estimates of prevalence.

Maternal Concentrations of Persistent Organochlorine Pollutants and the Risk of Asthma in Offspring: Results from a Prospective Cohort with 20 Years of Follow-up

Background: Previous findings suggest that developmental exposures to persistent organochlorine pollutants (POPs) may be detrimental for the development of the immune system in the offspring. Whether these suspected immunoregulatory effects persist beyond early childhood remains unclear. Objectives: The objective of this study was to evaluate the association between maternal serum concentrations of POPs and the risk of asthma in offspring after 20 years of follow-up. Methods: A birth cohort with 965 women was formed in 1988–1989 in Aarhus, Denmark. Concentrations of six polychlorinated biphenyls (PCBs) (congeners 118, 138, 153, 156, 170, 180), hexachlorobenzene (HCB), and dichlorodiphenyldichloroethylene (p,p´-DDE) were quantified in maternal serum (n = 872) collected in gestation week 30. Information about offspring use of asthma medications was obtained from the Danish Registry of Medicinal Product Statistics. Results: Maternal serum concentrations of HCB and dioxin-like PCB-118 were positively associated with offspring asthma medication use after 20 years of follow-up (p for trend < 0.05). Compared with subjects in the first tertile of maternal concentration, those in the third tertile of PCB-118 had an adjusted hazard ratio (HR) of 1.90 (95% CI: 1.12, 3.23). For HCB the HR for the third versus the first tertile of maternal concentration was 1.92 (95% CI: 1.15, 3.21). Weak positive associations were also estimated for PCB-156 and the non-dioxin-like PCBs (PCBs 138, 153, 170, 180). No associations were found for p,p´-DDE. Conclusions: Maternal concentrations of PCB-118 and HCB were associated with increased risk of asthma in offspring followed through 20 years of age. Citation: Hansen S, Strøm M, Olsen SF, Maslova E, Rantakokko P, Kiviranta H, Rytter D, Bech BH, Hansen LV, Halldorsson TI. 2014. Maternal concentrations of persistent organochlorine pollutants and the risk of asthma in offspring: results from a prospective cohort with 20 years of follow-up. Environ Health Perspect 122:93–99; http://dx.doi.org/10.1289/ehp.1206397