SummaryVenous blood was obtained from 100 consecutive and unselected Saudi Arabian mothers and their neonates within 48 h after delivery. Plasma levels of 25-hydroxyvitamin D (25-0HD) and total calcium were measured in paired samples. Fifty-nine mothers and 70 neonates had subnormal (less than 10 ngJml) 25-OHD levels. Plasma Ca concentrations were low in 61% of the mothers and 59% of the newborns consisting of 10 preterm and 38 full term babies. There were significant correlation between the plasma levels of maternal and neonatal 25-0HD (r = 0.54; P = 0.0001), maternal 25-0HD and Ca (r = -0.22; P = 0.03), neonatal 25-0HD and Ca (r =-0.28; P =0.0009), and maternal and neonatal calcium levels (r = 0.46; P = 0.0001). Nevertheless, maternal 25-0HD was not invariably higher than that in the infant. Normocalcemia was observed in 29 neonates and 26 mothers (20 mother/baby pairs) in the presence of subnormal maternal 25-0HD. Twenty babies and 16 mothers including nine mother/baby pairs had hypocalcemia in the presence of normal levels of 25-0HD. This indicates that vitamin D plays a crucial, but not exclusive, role in calcium homeostasis during pregnancy.This study revealed that vitamin D deficiency is very prevalent during pregnancy in Saudi Arabia. It also showed that asymptomatic hypocalcemia in full term babies is far commoner than is generally appreciated. It is considered that vitamin D deficiency is primarily due to lack of exposure to sunlight. Encouragement to obtain sunlight exposure and fortification of food are the only alternative measures. Abbreviation 25-0HD, 25-hydroxyvitamin D Saudis, especially women, avoid exposure to sunlight due to cultural and traditional beliefs. Ultraviolet light has been shown to produce changes in circulating 25-0HD equivalent to those produced by a daily dose of 10,000 IU i.e. several times the recommended daily adult intake in food (21). Second, the dietary intake of vitamin D by Saudi Arabians has been shown to be far below the amount recommended by FAO/WHO, in the United States and in the United Kingdom (20,24).In spite of abundant sunlight throughout the year, several vitamin D deficiency diseases have been reported in Saudi Arabia, including rickets (8,9), fractures of the head of the femur in the elderly, and osteomalacia (24). We have noticed a strikingly high incidence of hypocalcemia in full term infants delivered at King Abdul Aziz University Hospital. In view of the wide pre". alence of vitamin D deficiency diseases, we sought to define the role of this vitamin in the pathogenesis of neonatal hypocalcemia. Since 25-0HD is the major circulating form of vitamin D and since its plasma concentrations directly reflect its status (6), we opted to measure this metabolite and total calcium concentrations in mothers and their neonates. PATIENTS AND METHODS Clinical.A 5-ml sample of venous blood was taken from each of 100 unselected mothers and 2 ml from their corresponding babies, within 48 h of delivery at King Abdul Aziz University Hospital for estimation of plasma 25-0HD ...

Transcutaneous bilirubin measurements, using the Minolta transcutaneous bilirubinometer (TcB), were performed in 68 full-term, healthy Saudi infants. Infants who had exchange transfusion and those under phototherapy were excluded. One hundred and twenty measurements were obtained and compared with serum bilirubin levels measured by the American Optics (A.O.) bilirubinometer. The serum bilirubin range was 3.8-18.4 mg/dl. The results showed that the TcB index correlates well with the serum bilirubin measurement: the regression analysis was: r = 0.878, y = 10.78 + 0.909 x, P less than 0.001. However, the regression line showed that at a serum bilirubin level above 12.9 mg/dl the sensitivity of the TcB was 69% and the specificity 92%, while its positive and negative predictive values were 58% and 95% respectively. There was a fair amount of variability around the regression line which may lead to significant errors in clinical decision-making. Thus, the TcB at present has grave limitations which restrict its usefulness in the newborn.