Figure 3. Fetal glucose (A) and insulin (B) responses to an intravenous glucose tolerance test; arginine (C) and insulin (D) responses to an intravenous arginine challenge.

Areas under the curve shown as inset histograms. PCUN, periconceptional undernutrition. See text for details of nutritional groups. •, singleton N (SN) (n = 15); ○, singleton PCUN (SU) (n = 13); ▪, twin N (TN) (n = 26); □, twin PCUN (TU) (n = 30). Data are mean ±s.e.m.†P < 0.05 for twin effect; **P < 0.01 for nutrition effect; #P < 0.05 for twin–nutrition interaction.