No abstract

No abstract

Being born small for gestational age (SGA) confers increased risks of perinatal morbidity and mortality and increases the risk of cardiovascular complications and diabetes in later life. Accumulating evidence suggests that the etiology of SGA is usually associated with poor placental vascular development in early pregnancy. We examined metabolomic profiles using ultra performance liquid chromatographyÀmass spectrometry (UPLCÀMS) in three independent studies: (a) venous cord plasma from normal and SGA babies, (b) plasma from a rat model of placental insufficiency and controls, and (c) early pregnancy peripheral plasma samples from women who subsequently delivered a SGA baby and controls. Multivariate analysis by cross-validated Partial Least Squares Discriminant Analysis (PLS-DA) of all 3 studies showed a comprehensive and similar disruption of plasma metabolism. A multivariate predictive model combining 19 metabolites produced by a Genetic Algorithm-based search program gave an Odds Ratio for developing SGA of 44, with an area under the Receiver Operator Characteristic curve of 0.9. Sphingolipids, phospholipids, carnitines, and fatty acids were among this panel of metabolites. The finding of a consistent discriminatory metabolite signature in early pregnancy plasma preceding the onset of SGA offers insight into disease pathogenesis and offers the promise of a robust presymptomatic screening test.

Nutritional requirements for vitamin D during pregnancy have been inadequately described, and there are conflicting data on the impact of gestation on vitamin D status. In the present study, we conducted a longitudinal analysis of total and free (unbound) serum 25-hydroxyvitamin D (25(OH)D), vitamin D-binding protein (DBP) and albumin concentrations in a random sample of thirty women from the Screening for Pregnancy Endpoints Ireland pregnancy cohort study at 15,20,24, 28, 32, 36 and 40 weeks of gestation and at 2 months postpartum. Concentrations of serum 25(OH)D, DBP and albumin were determined, and free 25(OH)D was calculated from the concentrations of total 25(OH)D, DBP and albumin. Serum albumin concentration decreased during pregnancy (P,0·001), with a nadir at 36 weeks (P,0·005), during which the concentration was approximately 80 % of the postnatal concentration. Serum DBP concentration increased during pregnancy and at 28 weeks of gestation, which was almost double the postnatal level (P, 0·001). Total and free 25(OH)D concentrations decreased (both P, 0·005) as pregnancy progressed, and both were lowest at 36 weeks of gestation. At 15 weeks, 10 and 63 % of the women had serum 25(OH)D concentration , 30 and 50 nmol/l, respectively, which increased to 53 and 80 % at 36 weeks of gestation. The time course of decreasing concentrations of 25(OH)D during gestation among women recruited during May -July, who delivered between October and November, and among those recruited in August -September, who delivered between February and March, was similar. The lower percentage of free 25(OH)D during pregnancy is mainly due to increased DBP. Pregnancy is a life stage at which significant changes in vitamin D and Ca metabolism occur to provide the required Ca to the fetus for bone mineral accretion; however, nutritional requirements for vitamin D to promote healthy pregnancy are not known. The current suggested cut-offs for serum 25-hydroxyvitamin D (25(OH)D) concentrations representing vitamin D sufficiency/deficiency are based on the evidence from non-pregnant adults; however, it remains to be established whether there is an increased requirement for vitamin D intake during pregnancy and lactation (1,2) . A challenge of assessing vitamin D status during pregnancy is haemodilution. The expansion of maternal plasma volume begins as early as 6 weeks of gestation and continues until it reaches a net 40 % increase at 24-34 weeks of gestation (3) and an approximately 50 % increase by 36 weeks of gestation (4) . Thus, circulating concentrations of most nutrients decrease by the end of the first 10 weeks of gestation and remain lower than non-pregnancy values until term, even though the absolute total amount of vitamins and minerals in the circulation actually increases during pregnancy (5) . The increased blood volume during pregnancy is evidenced by the reduction in the concentration of circulating serum albumin (6) . Reference values for serum 25(OH)D concentrations based on non-pregnant adults are not necessaril...