| 1. |
- Björk, Jonas, et al.
(författare)
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An efficient sampling strategy for selection of biobank samples using risk scores
- 2017
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Ingår i: Scandinavian Journal of Public Health. - : SAGE Publications. - 1403-4948 .- 1651-1905. ; 45:17_suppl, s. 41-44
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Tidskriftsartikel (refereegranskat)abstract
- Aim: The aim of this study was to suggest a new sample-selection strategy based on risk scores in case-control studies with biobank data. Methods: An ongoing Swedish case-control study on fetal exposure to endocrine disruptors and overweight in early childhood was used as the empirical example. Cases were defined as children with a body mass index (BMI) ≥18 kg/m2 (n=545) at four years of age, and controls as children with a BMI of 1/217 kg/m2 (n=4472 available). The risk of being overweight was modelled using logistic regression based on available covariates from the health examination and prior to selecting samples from the biobank. A risk score was estimated for each child and categorised as low (0-5%), medium (6-13%) or high (≥14%) risk of being overweight. Results: The final risk-score model, with smoking during pregnancy (p=0.001), birth weight (p<0.001), BMI of both parents (p<0.001 for both), type of residence (p=0.04) and economic situation (p=0.12), yielded an area under the receiver operating characteristic curve of 67% (n=3945 with complete data). The case group (n=416) had the following risk-score profile: low (12%), medium (46%) and high risk (43%). Twice as many controls were selected from each risk group, with further matching on sex. Computer simulations showed that the proposed selection strategy with stratification on risk scores yielded consistent improvements in statistical precision. Conclusions: Using risk scores based on available survey or register data as a basis for sample selection may improve possibilities to study heterogeneity of exposure effects in biobank-based studies.
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| 2. |
- Malmqvist, Ebba, et al.
(författare)
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Fetal growth and air pollution - A study on ultrasound and birth measures
- 2017
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Ingår i: Environmental Research. - : Elsevier BV. - 0013-9351. ; 152, s. 73-80
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Tidskriftsartikel (refereegranskat)abstract
- Air pollution has been suggested to affect fetal growth, but more data is needed to assess the timing of exposure effects by using ultrasound measures. It is also important to study effects in low exposure areas to assess eventual thresholds of effects. The MAPSS (Maternal Air Pollution in Southern Sweden) cohort consists of linked registry data for around 48,000 pregnancies from an ultrasound database, birth registry and exposure data based on residential addresses. Measures of air pollution exposure were obtained through dispersion modelling with input data from an emissions database (NOx) with high resolution (100–500 m grids). Air pollution effects were assessed with linear regressions for the following endpoints; biparietal diameter, femur length, abdominal diameter and estimated fetal weight measured in late pregnancy and birth weight and head circumference measured at birth. We estimated negative effects for NOx; in the adjusted analyses the decrease of abdominal diameter and femur length were −0.10 (−0.17, −0.03) and −0.13 (−0.17, −0.01) mm, respectively, per 10 µg/m3 increment of NOx. We also estimated an effect of NOx-exposures on birth weight by reducing birth weight by 9 g per 10 µg/m3 increment of NOx. We estimated small but statistically significant effects of air pollution on late fetal and birth size and reduced fetal growth late in pregnancy in a geographic area with levels below current WHO air quality guidelines.
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| 3. |
- Malmqvist, Ebba, et al.
(författare)
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Gestational Diabetes and Preeclampsia in Association with Air Pollution at Levels below Current Air Quality Guidelines.
- 2013
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Ingår i: Environmental Health Perspectives. - : Environmental Health Perspectives. - 1552-9924 .- 0091-6765. ; 121:4, s. 488-493
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Tidskriftsartikel (refereegranskat)abstract
- Background: Several studies have estimated associations between air pollution and birth outcomes, but few have evaluated potential effects on pregnancy complications.Objective: We investigated whether low-level exposure to air pollution is associated with gestational diabetes and preeclampsia.Methods: High-quality registry information on 81,110 singleton pregnancy outcomes in southern Sweden during 1999-2005 was linked to individual-level exposure estimates with high spatial resolution. Modeled exposure to nitrogen oxides (NOx), expressed as mean concentrations per trimester, and proximity to roads of different traffic densities were used as proxy indicators of exposure to combustion-related air pollution. The data were analyzed by logistic regression, with and without adjusting for potential confounders.Results: The prevalence of gestational diabetes increased with each NOx quartile, with an adjusted odds ratio (OR) of 1.69 (95% CI: 1.41, 2.03) for the highest (> 22.7 µg/m3) compared with the lowest quartile (2.5-8.9 µg/m3) of exposure during the second trimester. The adjusted OR for acquiring preeclampsia after exposure during the third trimester was 1.51 (1.32, 1.73) in the highest quartile of NOx compared with the lowest. Both outcomes were associated with high traffic density, but ORs were significant for gestational diabetes only.Conclusion: NOx exposure during pregnancy was associated with gestational diabetes and preeclampsia in an area with air pollution levels below current air quality guidelines.
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| 4. |
- Malmqvist, Ebba, et al.
(författare)
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Maternal Exposure to Air Pollution and Birth Outcomes.
- 2011
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Ingår i: Environmental Health Perspectives. - : Environmental Health Perspectives. - 1552-9924 .- 0091-6765. ; 119, s. 553-558
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Tidskriftsartikel (refereegranskat)abstract
- Background: The knowledge about air pollution effects on birth weight, prematurity and small for gestational age [SGA] in low-exposure areas is insufficient. Objectives: The aim of this birth cohort study was to investigate if low-level exposure to air pollution was associated with prematurity and foetal growth and if there are gender specific effects. Method: We combined high quality registry information on 81110 births with individually modeled exposure data at residence for nitrogen oxides [NOx] and proximity to roads with differing traffic density. The data were analyzed by using logistic and linear regression with and without potential confounders. Results: An increased risk for babies being SGA was observed when highest and lowest NOx quartiles were compared, adjusting for maternal age, smoking, gender and year of birth. After additional adjustment for maternal country of origin and parity (which were highly intercorrelated), the increase was no longer statistically significant. However, in subgroup analysis when highest and lowest NOx quartiles were compared, there was still an increased risk for SGA for baby girls Odds Ratio [OR] 1.12 (95% Confidence Interval [CI] 1.01, 1.24), and also if mothers had not changed residency during pregnancy OR 1.09 (95% CI 1.01, 1.18). The confounders with the greatest impact on SGA were parity and country of origin. Concerning prematurity, the prevalence was lower in the three higher NOx exposure quartiles compared to the lowest category. Conclusion: For future studies on air pollution effects on birth outcomes careful control of confounding is crucial.
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| 5. |
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| 6. |
- Martinsson, Matilda, et al.
(författare)
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Intrauterine exposure to perfluorinated compounds and overweight at age 4 : A case-control study
- 2020
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 15:3
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Tidskriftsartikel (refereegranskat)abstract
- Aims The aims were to investigate the association between maternal serum levels of perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), perfluorohexane sulfonate (PFHxS) and perfluorononanoic acid (PFNA) in early pregnancy and overweight in the child at 4 years and to assess potential heterogeneity in exposure effect between strata with different levels of other risk factors for overweight. Methods We used a case-control design and included 354 cases (ISO-BMI ≥ 18 kg/m2) and 2 controls per case (ISO-BMI ≤17 kg/m2) from child health care centers in Malmö, Sweden. Controls were selected stratified on risk scores for overweight in a propensity score framework. Maternal serum levels were analyzed in biobanked samples collected by routine around gestational week 14. Logistic regression was used to estimate odds ratios between quartiles of maternal serum levels and child overweight at age 4. Results There were no consistent monotonic exposure-response relationships. We found some significant odds ratios in specific quartiles but these were regarded as spurious findings. The absence of an effect was consistent over risk strata. Conclusions We did not find evidence of an association between maternal serum levels of PFOS, PFOA, PFHxS and PFNA in early pregnancy and child overweight at age 4. The level of other risk factors for overweight did not affect children’s susceptibility to prenatal PFAS exposure.
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