Birth Weight Rather Than Maternal Nutrition Influences Glucose Tolerance, Blood Pressure, and IGF-I Levels in Sheep

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Both small size at birth in humans and maternal undernutrition in experimental animals are associated with impaired glucose tolerance and increased blood pressure in the adult offspring. However it is not clear whether maternal undernutrition in late gestation can influence postnatal phenotype, and whether this might occur independent of size at birth. We severely undernourished pregnant ewes for 10 d (UN10) or 20 d (UN20) from 105 d gestation (term = 146 d) and studied the offspring in comparison to those born to ad libitum fed ewes (AL20). Glucose tolerance tests and blood pressure recordings were performed at 5 mo of age and repeated at 30 mo together with insulin tolerance tests and GH challenges. UN20 lambs were lighter at birth (UN20, 4.9 ± 0.1 kg, n = 23; UN10, 5.3 ± 0.1 kg, n = 26; AL20, 5.6 ± 0.2 kg, n = 26) but not from weaning onward. Plasma glucose area under the curve at 5 mo and plasma insulin at 30 mo increased with current weight and decreased with increasing birth weight. Blood pressure also increased with current weight and decreased with increasing birth weight at 5 but not 30 mo. Plasma IGF-I concentrations increased with current weight at all ages and decreased with increasing birth weight at 30 mo. Plasma insulin response to GH challenge increased with current weight. Nutrition group was not related to any of the outcomes measured when birth weight and current weight were taken into account. These data suggest that size at birth is more closely related to processes that determine postnatal phenotype than is maternal nutrition in late gestation.