Decreased maternal lipolysis in intrauterine growth restriction in the third trimester.

OBJECTIVE: Intrauterine growth restriction (IUGR) is a common complication of pregnancy. There are many possible aetiologic factors of maternal, placental and/or fetal origin. Often there is no known explanation. The aim of this study was to investigate whether a reduction in maternal energy substrate production could be one of the factors involved in IUGR. DESIGN: Measurement of maternal energy substrate production and glucoregulatory hormones in women with growth-restricted fetuses. SETTINGS: University Hospital, Uppsala, Sweden. POPULATION: Ten healthy pregnant women with IUGR were compared with eight recently reported healthy women with normal pregnancies. The women were studied at 35.4+/-1.6 weeks of gestation after an overnight fast. METHODS: Rates of glycerol and glucose production were analysed by gas chromatography/mass spectrometry following constant-rate infusion of [1,1,2,3,3-(2)H5]glycerol and [6,6-(2)H2]glucose. MAIN OUTCOME MEASURE: Third trimester glycerol and glucose production. RESULTS: Glycerol production, reflecting lipolysis, was lower in the women with IUGR than in those with normal pregnancies, 2.36+/-0.58 versus 3.06+/-0.66 micromol kg-1 minute-1 (P=0.033), whereas there was no difference in rate of glucose production (glucose production rate [GPR]), 12.1+/-1.5 versus 13.2+/-1.5 micromol kg-1 minute-1 (P=0.23). Plasma glycerol levels were increased in the women with IUGR (P=0.008). CONCLUSIONS: Lipolysis is lower in pregnancies complicated by IUGR as compared with normal pregnancies. Increased lipolysis during pregnancy provides substrate for maternal energy metabolism, which spares glucose for the fetus. A reduced maternal production of energy substrate could be one of several factors underlying IUGR. A lack of relationship between insulin levels and either lipolysis or GPR suggests defective regulation of energy substrate production in this group of pregnant women.

Effect of theophylline on glucose production and lipolysis in preterm infants (< or = 32 weeks).

Apnea occurs commonly in preterm infants. Theophylline is used as prophylaxis and treatment. Apart from improving ventilatory function, theophylline may also have metabolic effects, including an effect on glucose metabolism and lipolysis. No data are available on the effect of theophylline on glucose production and lipolysis in preterm infants at start of medication. Ten preterm infants with gestational ages of < or = 32 wk, postnatal ages of 16-84 h, and birth weights > 900 g were recruited. Hepatic glucose production and lipolysis were measured by use of gas chromatography/mass spectrometry after constant rate infusion of [6,6-2H2]glucose and [2-13C]glycerol tracers. Plasma glucose levels increased after theophylline administration (mean +/- SD, 4.0 +/- 1.9 mmol/L before and 4.7 +/- 2.1 mmol/L after start of therapy), whereas the rate of glucose production decreased (6.0 +/- 2.5 mg.kg-1.min-1 and 4.3 +/- 1.9 mg.kg-1.min-1, respectively). The plasma glycerol concentration did not show any change after theophylline administration (154 +/- 257 mumol/L before and 217 +/- 258 mumol/L after), and the same was true for the rate of glycerol production (5.9 +/- 2.6 mumol.kg-1.min-1 before and 6.7 +/- 3.0 mumol.kg-1.min-1 after). The fraction of glycerol converted into glucose did not change significantly, although the percentage of glucose derived from glycerol increased after theophylline administration. The results are in line with the lack of adverse metabolic effects at start of theophylline treatment in the preterm infant.