Metabolic response to meal eating and extended overnight fast in twin gestation

Objective: Our purpose was to compare the metabolic response to normal meal eating and the vulnerability to starvation ketosis in twin versus singleton gestation. Study Design: Data are reported on 10 twin and 10 singleton nondiabetic gestations enrolled in a 40-hour metabolic study. Singletons were age (±5 years) and pregnancy weight (±10% ideal body weight) matched with twins. The diet (35 kcal/kg ideal body weight for singletons, 40 kcal/kg ideal body weight for twins) was distributed as one fifth at 8 am, two fifths at 1 pm, and two fifths at 6 pm. An overnight fast was extended until noon the following day. Glucose and β-hydroxybutyrate measurements were made hourly except at night, when they were made every 2 hours. Insulin values were obtained before and after dinner and on the day when breakfast was delayed. Results: The glucose, β-hydroxybutyrate, and insulin excursions in response to meal eating from 8 am to 12:00 noon on day 1 were similar in twin and singleton pregnancies (analysis of variance for repeated measures, p<0.05). On day 2, when breakfast was delayed, a progressive decrement in glucose was observed in both twins and singletons (p=0.4682). Concurrently, there was a progressive rise in β-hydroxybutyrate in both twins and singletons, which was significantly greater for twins compared with singletons (p=0.002). Conclusions: These data indicate that twin gestations are more vulnerable to the accelerated starvation of late normal pregnancy than singletons are in spite of additional caloric intake. We speculate that the observed difference may be the result of the increased metabolic demands of twin gestation.