Serum Concentrations of Vitamin D Metabolites in Exclusively Breast-Fed Infants at 70° North

ABSTRACT. The effect of prolonged breast-feeding on the serum concentrations of vitamin D metabolites, calcium, phosphate, and alkaline phosphatase was studied longitudinally in 7 infants from Northern Norway. They were exclusively breast-fed for a median of 71/2 months. Three of the mothers were supplemented with vitamin D throughout lactation. All but one of the infants had 25-hydroxyvitamin D (25-OHD) levels in the rachitic range (< 20 nmol/l) on at least one occasion. Vitamin D supplementation of the mother had no apparent effect on the infants' 25-OHD levels, but the values increased during summer. The infant who had the lowest 25-OHD levels also had decreased 1,25-dihydroxyvitamin D (1,25-(OH)₂D) concentrations, while the others maintained l,25-(OH)₂D levels within normal limits. 24,25-(OH)₂D concentrations were undetectable when the 25-OHD levels were below 35 nmol/l, but the two metabolites were closely correlated for higher values of 25-OHD. Low 25-OHD levels were associated with decreased phosphate concentrations at 6 months. The calcium levels were normal throughout the study period of one year, as were all but two of the alkaline phospatase values. Although none of the infants had clinical or biochemical evidence of rickets, the results suggest that the vitamin D supply from human milk is inadequate, and that routine vitamin D supplementation is advisable for breast-fed infants who are deprived of sunlight exposure.     

Birth weight related to social indicators in Norway

The relationship between parental social position and birthweight is being studied. A total population of 102,638 singleborn, first-born infants was included in the study. Census informationfrom 1980 was linked to the Medical Birth Registry for the years1978-1982. Children of parents with a high education (more than15 years) had the highest birth weight. The association wasdistinct and linear between low birth weight and education.The same tendency appeared for paternal socio-economic status,but differences were comparatively small. When examining incomethe pattern was different. The highest maternal income grouphad the highest proportion of low birth weight offspring. Whenexamining parental education jointly, it was found that themothers' education had the greatest impact on birth weight.By adjusting for female smoking, using survey data, the associationbetween maternal education and birth weight was weakened. However,assuming that birth weight is decreased by 200 g from smoking,the effect was still significant.     

Soluble Tumor Necrosis Factor Receptor in Serum and Urine Throughout Normal Pregnancy and at Delivery

PROBLEM : To determine the concentration of the two soluble tumor necrosis factor receptors (sTNFR), sp55 and sp75, in healthy pregnant women. METHOD : Serum and urine samples were longitudinally collected from a group of pregnant women (N=53) five times throughout pregnancy. Maternal and umbilical sera were obtained from some of the deliveries (N=31). The samples were analysed using ELISA based on two monoclonal antibodies (IV4E and 3H5) against the soluble tumor necrosis factor receptors (sp55 and sp75). RESULTS : Serum concentration of sp55 and sp75 were increased in pregnant women compared to that of nonpregnant controls. Concentration of both sTNFRs increased towards term. Labor was associated with further increase of sp55. Concentrations of sp55 and sp75 in umbilical serum were significantly higher than those of maternal serum. Significant correlations were observed between maternal and umbilical sTNFR concentrations. CONCLUSIONS : The current study suggests that pregnancy is associated with an activation of mechanisms regulating the biological activities of TNF.