Associations of Maternal Vitamin B12 Concentration in Pregnancy With the Risks of Preterm Birth and Low Birth Weight: A Systematic Review and Meta-Analysis of Individual Participant Data.

Vitamin B12 (hereafter referred to as B12) deficiency in pregnancy is prevalent and has been associated with both lower birth weight (birth weight <2,500 g) and preterm birth (length of gestation <37 weeks). Nevertheless, current evidence is contradictory. We performed a systematic review and a meta-analysis of individual participant data to evaluate the associations of maternal serum or plasma B12 concentrations in pregnancy with offspring birth weight and length of gestation. Twenty-two eligible studies were identified (11,993 observations). Eighteen studies were included in the meta-analysis (11,216 observations). No linear association was observed between maternal B12 levels in pregnancy and birth weight, but B12 deficiency (<148 pmol/L) was associated with a higher risk of low birth weight in newborns (adjusted risk ratio = 1.15, 95% confidence interval (CI): 1.01, 1.31). There was a linear association between maternal levels of B12 and preterm birth (per each 1-standard-deviation increase in B12, adjusted risk ratio = 0.89, 95% CI: 0.82, 0.97). Accordingly, B12 deficiency was associated with a higher risk of preterm birth (adjusted risk ratio = 1.21, 95% CI: 0.99, 1.49). This finding supports the need for randomized controlled trials of vitamin B12 supplementation in pregnancy.

New advice on vitamin D supplements and cod liver oil for infants. / Nye råd om D-vitamintilskudd og tran til spedbarn.

Until recently, all parents have been advised to give cod liver oil to their infants. Now, cod liver oil is no longer recommended during the first year of life, but breastfed infants still need vitamin D supplements.

Maternal folate and cobalamin status predicts vitamin status in newborns and 6-month-old infants.

Our aim in this longitudinal study was to determine predictors of folate and cobalamin status in infancy. Data were collected from 364 mother-infant pairs with blood measurements from pregnancy ( approximately 18 wk; n = 149), newborns (cord serum; n = 361), and 6-mo-old partially or exclusively breast-fed children (n = 221). Serum/plasma folate, cobalamin, holotranscobalamin (holoTC), holohaptocorrin (holoHC), methylmalonic acid (MMA) and total homocysteine (tHcy) at birth and 6 mo were related to maternal vitamin status, parity, lifestyle variables, and anthropometry. In multivariate analyses, the strongest predictors of folate at birth and 6 mo were maternal folate and cord folate, respectively (P < 0.01). Maternal holoTC best predicted cobalamin status at birth (positively associated with cord cobalamin, holoTC, and holoHC; inversely with MMA and tHcy; P < or = 0.001), whereas maternal and cord holoHC were the strongest predictors of cobalamin status at 6 mo (positively associated with cobalamin, holoTC, holoHC; inversely with tHcy; P < 0.05). The association between cobalamin status and parity was negative at birth but positive at 6 mo. Birth weight, female sex, and smoking were associated with low cobalamin or high tHcy at birth but showed no or opposite associations at 6 mo. In conclusion, maternal folate and cobalamin status exerts a long-term positive effect on infant vitamin status. The effect of smoking, parity and female sex on cobalamin status did not persist beyond the newborn period. Maternal holoTC was the superior predictor of newborn cobalamin status, while holoHC could be a valuable marker for predicting cobalamin status later in infancy.

Predictors of serum ferritin and serum soluble transferrin receptor in newborns and their associations with iron status during the first 2 y of life.

BACKGROUND: Adequate iron status at birth may prevent iron deficiency in early childhood. OBJECTIVES: We aimed to identify predictors of serum ferritin (SF) and serum soluble transferrin receptor (sTfR) in healthy newborns and to relate these iron indexes to iron status in the first 2 y of life. DESIGN: Using bivariate correlations and linear regression, we related various factors in pregnancy to SF (n=363) and sTfR (n=350) in healthy, term infants. Measurements of cord SF and sTfR were compared with those of SF and sTfR at 6, 12, and 24 mo. All 4 measurements were available for 191 and 169 infants for SF and sTfR, respectively. RESULTS: Geometric mean (and 95% CI) cord SF and sTfR measurements were 159 (148, 171) microg/L and 7.3 (7.0, 7.6) mg/L, respectively. Cord SF correlated with sTfR (rho=-0.21, P<0.001). In regression analysis, cord SF correlated with smoking and the use of iron supplements during pregnancy (partial r=-0.12 and 0.16; P<0.05 for both). Cord sTfR was associated with first trimester BMI, gestational age, and male sex (partial r=0.30, 0.24, and 0.19, respectively; P<0.01 for all). Cord SF correlated with SF at 6, 12, and 24 mo (rho=0.45, 0.31, and 0.16 respectively; P<0.05 for all). At age 6 mo, 16 of 17 infants with SF <15 mug/L were boys. CONCLUSIONS: Cessation of smoking and adequate iron prophylaxis during pregnancy may improve iron status in infancy. Cord SF is a predictor of iron status in the first 2 y of life. Boys are at particular risk of low iron status in early infancy.

Folate and cobalamin status in relation to diet in healthy 2-y-old children.

BACKGROUND: Limited data exist on sources of folate and cobalamin in the toddler diet. OBJECTIVE: We examined the influence of diet on folate and cobalamin status in healthy toddlers in an unfortified population. DESIGN: Dietary intake was assessed in 178 children, aged 24 mo, by using 7-d food records and related to serum folate and cobalamin status in 155 children. RESULTS: Median (25th-75th percentile) daily intakes of folate and cobalamin were 87 µg (74-104 µg) and 3.1 µg (2.4-3.8 µg), respectively. Thirty-five percent of subjects had a folate intake below the Norwegian recommendations (80 µg folate/d), but only 5.8% of subjects had low serum folate concentrations (<10 nmol/L). All children reached the recommended cobalamin intake (0.8 µg cobalamin/d). Median (25th-75th percentile) serum concentrations were as follows: folate, 19 nmol/L (14-24 nmol/L); cobalamin, 410 pmol/L (334-521 pmol/L); holotranscobalamin, 94 pmol/L (67-121 pmol/L); holohaptocorrin, 315 pmol/L (241-409 pmol/L); methylmalonic acid, 0.16 µmol/L (0.13-0.20 µmol/L); and total homocysteine, 5.0 µmol/L (4.2-5.7 µmol/L). Folate intake correlated with serum folate concentrations (ρ = 0.25, P < 0.01), and cobalamin intake correlated with serum holotranscobalamin concentrations (ρ = 0.21, P < 0.05). In multivariate models, serum folate concentrations were significantly positively associated with the consumption of fruit and berries and grain products; however, this was not the case with dairy products, which was the food group that contributed most to folate intake. Cobalamin status was associated with dairy products (cobalamin and holotranscobalamin), cobalamin supplements (cobalamin and holohaptocorrin), and liver pâté (holotranscobalamin). CONCLUSIONS: In this unfortified toddler population, folate status was associated with intakes of fruit and berries and grain products. Cobalamin status was associated with intakes of dairy, liver pâté, and supplements. In the assessment of vitamin sources, vitamin availability must be considered.

Folate and cobalamin status in relation to breastfeeding and weaning in healthy infants.

BACKGROUND: Folate and cobalamin status changes markedly during infancy. OBJECTIVE: We aimed to examine the influence of breastfeeding on folate and cobalamin status in healthy infants. DESIGN: In a longitudinal study, we measured serum folate, cobalamin, holotranscobalamin, holohaptocorrin, methylmalonic acid, and homocysteine at birth and at ages 6, 12, and 24 mo (n = 361, 262, 244, and 224, respectively). Breastfeeding status and nutrient intake were assessed by using questionnaires and 7-d weighed-food records (at 12 mo). RESULTS: All indexes changed significantly from birth to age 24 mo (P < 0.001). Folate was high until age 6 mo and then declined. At age 6 mo, folate was positively correlated with duration of exclusive breastfeeding (rho = 0.29; P < 0.001). Cobalamin status declined after birth in breastfed but increased in nonbreastfed infants. Thus, holotranscobalamin (pmol/L) was lower in breastfed than in nonbreastfed children at age 6 mo [geometric mean: 37 (95% CI: 33, 40) and 74 (64, 86), respectively], at 12 mo [51 (46, 56) and 76 (70, 82), respectively], and at 24 mo [65 (50, 83) and 90 (85, 97), respectively; P < 0.05 for all]. Complementary feeding did not increase (6 mo) or modestly increased (12 mo) cobalamin status in breastfed children. At 12 mo, cobalamin intake (microg/d), excluding breast milk cobalamin, was lower in breastfed than in nonbreastfed infants [geometric mean: 1.4 (1.3, 1.6) and 2.4 (2.1, 2.6), respectively; P < 0.001]. However, after adjustment for total cobalamin intake, cobalamin status (ie, holotranscobalamin) remained significantly lower in breastfed than in nonbreastfed infants [54 (49, 59) and 70 (64, 78), respectively; P < 0.001]. CONCLUSIONS: Low cobalamin status is a characteristic finding in breastfed children. Reference limits according to age and breastfeeding status should be considered in early childhood.