Objectives: To examine the associations between maternal vitamin D intake and childhood growth and risk of overweight up to 8 years. We further examined the effect modification by maternal prepregnancy body mass index (BMI).Design: Prospective population-based pregnancy cohort study.Setting: The Norwegian Mother, Father and Child Cohort Study.Participants: In total, 58 724 mothers and 66 840 singleton children, with information on maternal vitamin D intake during the pregnancy and minimum one postnatal anthropometric measurement.Outcome measures: Predicted weight and height growth trajectories and velocities from 1 month to 8 years, rapid growth during infancy and toddlerhood, and risk of overweight in preschool and school age.Results: Overall, maternal vitamin D intake was associated with lower weight trajectory, lower odds of rapid weight growth and higher odds of childhood overweight. In children of mothers with prepregnancy normal weight, maternal vitamin D intake was negatively associated with weight trajectory and lower OR of a rapid weight growth during the first year, compared with reference (15 µg/day, also had 0.86 (95% CI 0.77 to 0.97) and 0.88 (95% CI 0.79 to 0.99) lower odds for overweight at 3 years, compared with reference. In contrast, in children of mothers with prepregnancy overweight (BMI ≥25 kg/m²), vitamin D intake was positively associated with weight trajectory. Children of mothers with overweight, with maternal vitamin D intake of 5–9.9 µg/day, also had (1.09 (95% CI 1.01 to 1.18) and 1.12 (95% CI 1.02 to 1.23)) higher odds for overweight at 5 years and 8 years, compared with reference.Conclusions: Maternal vitamin D intake affects postnatal growth and is inversely associated with childhood overweight in children of mothers with normal weight. Associations between maternal vitamin D intake and child growth and risk of overweight varied by prepregnancy BMI.

Background: Early childhood growth can affect the child's health status later in life. Maternal vitamin D status has been suggested to affect early childhood growth. However, there is a lack of studies investigating the role of maternal vitamin D status on growth trajectories during infancy. By using growth mixture modeling (GMM), maternal vitamin D status during pregnancy can be investigated in relation to different classes of infant growth trajectories.Objectives: To examine the association between maternal 25‐hydroxyvitamin D (25OHD) and classes of infant body mass index (BMI) growth trajectories.Methods: Mother–child pairs were included from the Norwegian Mother, Father, and Child Cohort Study (MoBa,n= 2522) and the Swedish GraviD cohort (n = 862). Maternal 25OHD in pregnancy was analyzed by liquid chromatography tandem mass spectrometry. Children's weights and heights were registry‐based. GMM identified classes of infant BMI growth trajectories up to 2 years. The association between maternal 25OHD and infant BMI class by cohort was estimated using a log‐link generalized linear model. Mixed model analysis estimated the pooled association including both cohorts.Results: Two infant BMI classes were identified, stable normal and stable high. In MoBa, maternal 25OHD 75 nmol/L. In GraviD, no association was found. In pooled analysis, maternal 25OHD ≤75 nmol/L was non‐significantly associated with a higher risk of the stable high BMI growth class.Conclusions: Maternal 25OHD ≤75 nmol/L may be associated with a higher class of BMI growth trajectory during infancy.

The objective was to develop and validate a non-invasive screening tool to identify pregnant women at high risk of vitamin D deficiency. Data from the Swedish prospective cohort GraviD, 2125 pregnant women, were randomly split in halves; one for developing the screening tool, and one for validation. Risk factors of vitamin D deficiency (serum 25-hydroxyvitamin D < 30 nmol/L) were identified using logistic regression analyses and odds ratios were translated into scores. Cutt offs to indicate high risk of vitamin D deficiency were evaluated by receiver operator characteristics. Five variables (season, clothing, eye color, fortified milk intake and vitamin D supplement use) were included in the screening tool. The possible total score was 0-42. Mean (95% CI) area under the curve for classification of vitamin D deficiency was 0.921 (0.893-0.948) (p < 0.001). A score of ≥15 points had 92% sensitivity and 76% specificity to identify women with 25OHD <30 nmol/L. This cut off had a positive predictive value of 31% and a negative predictive value of 99%. This short non-invasive screening tool is valid as it correctly identified the majority of the vitamin D deficient pregnant women, who may benefit from further investigation for definite diagnosis and subsequent treatment.

Background: Norwegian data on vitamin D status among pregnant women indicate a moderate to high prevalence of insufficient vitamin D status (25-hydroxyvitamin D (25OHD) concentrations ≤50 nmol/L). There is a lack of population-based research on vitamin D intake and determinants of 25OHD in pregnant women from northern latitudes. The aims of this study were (1) to evaluate total vitamin D intake from both diet and supplements, (2) to investigate determinants of vitamin D status, and (3) to investigate the predicted response in vitamin D status by total vitamin D intake, in pregnant Norwegian women.Methods: In total, 2,960 pregnant women from The Norwegian Environmental Biobank, a sub-study within The Norwegian Mother, Father and Child Cohort Study (MoBa), were included. Total vitamin D intake was estimated from a food frequency questionnaire in gestational week 22. Concentrations of plasma 25OHD was analyzed by automated chemiluminescent microparticle immunoassay method in gestational week 18. Candidate determinant variables of 25OHD were chosen using stepwise backward selection and investigated using multivariable linear regression. Predicted 25OHD by total vitamin D intake, overall and stratified by season and pre-pregnancy BMI, was explored using restricted cubic splines in an adjusted linear regression.Results: Overall, about 61% of the women had a total vitamin D intake below the recommended intake. The main contributors to total vitamin D intake were vitamin D supplements, fish, and fortified margarine. Higher 25OHD concentrations were associated with (in descending order of the beta estimates) summer season, use of solarium, higher vitamin D intake from supplements, origin from high income country, lower pre-pregnancy BMI, higher age, higher vitamin D intake from foods, no smoking during pregnancy, higher education and energy intake. During October–May, a vitamin D intake according to the recommended intake was predicted to reach sufficient 25OHD concentrations >50 nmoL/L.Conclusion: The findings from this study highlight the importance of the vitamin D intake, as one of few modifiable determinants, to reach sufficient 25OHD concentrations during months when dermal synthesis of vitamin D is absent.

In utero exposure to deficiencies of certain nutritional factors such as vitamin D has been related to adverse cardiometabolic outcomes in the offspring, but results are conflicting. The aim of this study was to investigate the association between maternal vitamin D status during pregnancy and markers of cardiometabolic risk in childhood. Serum 25-hydroxyvitamin D (25OHD) concentrations were measured at 11- and 33-weeks' gestation. At 7-8 years of age, the children were examined regarding anthropometry, body composition (by bioelectrical impedance), and blood pressure, and a blood sample was drawn. Cardiometabolic risk was assessed using individual cardiometabolic risk factors and a composite score of adiposity, blood pressure, blood lipids, and hemoglobin A1c, using age- and sex-specific z-scores. Associations between maternal vitamin D status in early and late pregnancy and z-scores of markers of cardiometabolic risk were evaluated using adjusted linear and logistic regression analyses. In total, n = 172 mother-child pairs were included. Neither was an association found between maternal 25OHD concentration with a composite score of cardiometabolic risk in childhood (Odds Ratio (OR) 1.02 (confidence interval (CI) 0.99-1.05), and OR 0.99 (CI 0.97-1.01) in early and late pregnancy, respectively), nor with any individual marker of cardiometabolic risk. In conclusion, there were no evidence of an association between maternal vitamin D status during pregnancy and cardiometabolic risk factors in the child at 7-8 years of age.

Introduction: Maternal vitamin D status during pregnancy has been suggested to have a role in childhood adiposity development, but results are conflicting. Our aims were to investigate [1] the relationships between maternal 25-hydroxyvitamin D (25OHD) during pregnancy and the child’s body mass index (BMI) and risk of overweight at 5 years of age, and [2] maternal pre-pregnancy BMI as effect modifier for these associations.Methods: Data sources included a subsample from the Norwegian Mother, Father and Child Cohort Study (MoBa sub-cohort; N = 2,744) and the Swedish GraviD cohort study (N = 891). Maternal 25OHD was analyzed in gestational week 18 in the MoBa sub-cohort and week 10 in the GraviD cohort. In the MoBa sub-cohort, parents reported their child’s documented measures of weight and length or height from the health card at routine check-up. In the GraviD cohort, this information was collected directly from medical records. Childhood overweight (including obesity) was identified using the International Obesity Task Force cut-offs. Linear and logistic regression models were used to investigate the association between maternal 25OHD and child’s BMI and risk of overweight at 5 years of age in each cohort separately, and in a pooled dataset.Results: In the pooled analysis, maternal 25OHD <30 nmol/L was associated with lower BMI in children at 5 years of age, but not with risk of overweight. Interaction analysis showed that the association was predominant among children of mothers with pre-pregnancy BMI ≥25 kg/m².Conclusion: Low maternal vitamin D status, particularly in mothers with overweight or obesity, predicted lower BMI in their five-year-old children. However, there was no evidence of an effect on overweight in these children.