This study was to determine whether pregnancy affects maximal aerobic power. We measured heart rate, O2 uptake (VO2), CO2 production (VCO2), and ventilation at rest and during bicycle (BE) and treadmill exercise (TE) tests with rapidly increasing exercise intensities at 16, 25, and 35 wk gestation and 7 wk after delivery. Maximal heart rate was slightly lower throughout pregnancy compared with the nonpregnant state during both BE [174 +/- 2 vs. 178 +/- 2 (SE) beats/min] and TE (178 +/- 2 vs. 183 +/- 2 beats/min). Maximal VO2 was unaffected by pregnancy during BE and TE (2.20 +/- 0.08, 2.16 +/- 0.08, 2.15 +/- 0.08, and 2.19 +/- 0.08 l/min for BE and 2.45 +/- 0.08, 2.38 +/- 0.09, 2.33 +/- 0.09, and 2.39 +/- 0.08 l/min for TE at 16, 25, and 35 wk gestation and 7 wk postpartum, respectively). As a result of increased VO2 at rest, the amount of O2 available for exercise (exercise minus rest) tended to decrease with advancing gestation, reaching statistical significance only during TE at 35 wk gestation (1.99 +/- 0.08 l/min vs. 2.10 +/- 0.08 l/min postpartum). Power showed a positive linear correlation with O2 availability during BE as well as TE, and the relationship was unaffected by pregnancy.(ABSTRACT TRUNCATED AT 250 WORDS)

Catecholamine levels were measured in cord arterial blood from preterm infants. Relatively lower catecholamine levels were found in the preterm infants than in term infants, although no significant correlation was found between noradrenaline and adrenaline levels and either gestational age or birthweight. Significantly higher catecholamine levels were found after labour. Preterm females had significantly higher catecholamine levels than boys after asphyxia and tended also to have higher catecholamine levels without asphyxia, although not significant. Catecholamine levels were also significantly elevated in those infants with a low Apgar score (less than 7 at 5 min) and those who were acidotic (cord arterial pH less than 7.25). A good correlation was found between a low Apgar score and the presence of acidosis.

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Prior cardiovascular disease, smoking, and a recent episode of fatigue or flu-like symptoms are associated with an increased risk of exercise-related acute cardiac events. Athletes and physicians should pay careful attention when these factors exist or occur.