Vitamin D intake and determinants of vitamin D status during pregnancy in The Norwegian Mother, Father and Child Cohort Study.

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.

Patterns and dietary determinants of essential and toxic elements in blood measured in mid-pregnancy: The Norwegian Environmental Biobank.

BACKGROUND: Inadequate stores or intakes of essential minerals in pregnancy, or too high exposure to both toxic and essential elements, can have adverse effects on mother and child. The main aims of this study were to 1) describe the concentrations and patterns of essential and toxic elements measured in maternal whole blood during pregnancy; 2) identify dietary, lifestyle and sociodemographic determinants of element status; and 3) explore the impact of iron deficiency on blood element concentrations. METHODS: This study is based on blood samples collected from 2982 women in gestational week 18 in The Norwegian Mother and Child Cohort study (MoBa) which were analyzed as part of the Norwegian Environmental Biobank. We derived blood element patterns by exploratory factor analysis, and associations between blood element patterns and diet were explored using sparse partial least squares (sPLS) regression. RESULTS: Blood concentrations were determined for the essential elements (in the order of most abundant) Zn > Cu > Se > Mn > Mo > Co, and the toxic metals Pb > As > Hg > Cd > Tl. The concentrations were in ranges that were similar to or sometimes more favorable than in other pregnant and non-pregnant European women. We identified two blood element patterns; one including Zn, Se and Mn and another including Hg and As. For the Zn-Se-Mn pattern, use of multimineral supplements was the most important dietary determinant, while a high score in the Hg-As pattern was mainly determined by seafood consumption. Concentrations of Mn, Cd and Co were significantly higher in women with iron deficiency (plasma ferritin < 12 µg/L) than in women with plasma ferritin ≥ 12 µg/L. CONCLUSION: Our study illustrates complex relationships and coexistence of essential and toxic elements. Their potential interplay adds to the challenges of studies investigating health effects related to either diet or toxicants.

The effect of high doses of folic acid and iron supplementation in early-to-mid pregnancy on prematurity and fetal growth retardation: the mother-child cohort study in Crete, Greece (Rhea study).

PURPOSE: We examined whether high doses of folic acid and iron supplementation in early-to-mid pregnancy affect the risk of preterm birth, low birth weight, and small for gestational age neonates, in the mother-child cohort in Crete, Greece (Rhea study). METHODS: We included 1,279 women with singleton pregnancies with complete data on supplements use in early-to-mid pregnancy and birth outcomes. Anthropometric measurements at birth were obtained from medical records. Red blood cell folate concentrations in cord blood were measured in a subsample of the study population (n = 58). RESULTS: Sixty-six percent of the study participants reported high doses of supplemental folic acid use (5 mg/day), while 21 % reported excessive doses of folic acid use (>5 mg/day) in early-to-mid pregnancy. Daily intake of 5-mg supplemental folic acid was associated with a 31 % decrease in the risk of preterm birth (RR, 0.69; 95 % CI, 0.44, 0.99), 60 % decrease in the risk of delivering a low birth weight neonate (RR, 0.40; 95 % CI, 0.21, 0.76), and 66 % decrease in the risk of delivering a small for gestational age (SGA) neonate (RR, 0.34; 95 % CI, 0.16, 0.73). Daily doses of iron supplementation more than 100 mg were associated with a twofold increased risk for SGA neonates (RR, 2.14; 95 % CI, 0.99, 5.97). CONCLUSION: These findings suggest that high daily doses of supplementary folic acid in early-to-mid pregnancy may be protective for preterm birth, low birth weight, and small for gestational age neonates, while high daily doses of supplementary iron may be harmful for fetal growth.

Effect of high doses of folic acid supplementation in early pregnancy on child neurodevelopment at 18 months of age: the mother-child cohort 'Rhea' study in Crete, Greece.

OBJECTIVE: To investigate whether high doses of folic acid supplementation in early pregnancy are associated with child neurodevelopment at 18 months of age. DESIGN: The study uses data from the prospective mother-child cohort 'Rhea' study. Pregnant women completed an interviewer-administered questionnaire on folic acid supplementation at 14-18 weeks of gestation. Neurodevelopment at 18 months was assessed with the use of the Bayley Scales of Infant and Toddler Development (3rd edition). Red-blood-cell folate concentrations in cord blood were measured in a sub-sample of the study population (n 58). SETTING: Heraklion, Crete, Greece, 2007-2010. SUBJECTS: Five hundred and fifty-three mother-child pairs participating in the 'Rhea' cohort. RESULTS: Sixty-eight per cent of the study participants reported high doses of supplemental folic acid use (5 mg/d), while 24 % reported excessive doses of folic acid (>5 mg/d) in early pregnancy. Compared with non-users, daily intake of 5 mg supplemental folic acid was associated with a 5-unit increase on the scale of receptive communication and a 3·5-unit increase on the scale of expressive communication. Doses of folic acid supplementation higher than 5 mg/d were not associated with additional increase in the neurodevelopmental scales. CONCLUSIONS: This is the first prospective study showing that high doses of supplementary folic acid in early pregnancy may be associated with enhanced vocabulary development, communicational skills and verbal comprehension at 18 months of age. Additional longitudinal studies and trials are needed to confirm these results.