부산대학교 도서관

Smoking during pregnancy leads to lower birthweights in infants, possibly due to displacement of oxygen from maternal and fetal hemoglobin by carbon monoxide. We measured maternal and fetal O2Hb% and COHb% saturation in 4 pregnant ewes after a single smoke using reference tobacco (T), marijuana (M), or marijuana placebo (p) cigarettes. Femoral artery catheters were implanted into ewes and fetuses at 130 days gestation. At 133-140 days, fetal and maternal O2Hb% and COHb% saturations were determined before, during, and for 24 hr after a continuous 10 min exposure to T, M, or P delivered to the standing ewe through an open-ended tracheal T-tube. The sequence of exposure to T (n=4), M (n=3), and P (n=3) was randomized with >48 hr recovery between exposures. Data (mean±SD) were analyzed by ANOVA and, if p <0.05, a multiple comparison procedure was performed.After the 10 min. smoke, maternal O2Hb% dropped from 94±1 to < 92 ± 1 for 2 hr. Maternal COHb% rose from 2.0 ± 0.5 to a peak of 6.3 ± 2 at 15 min, and slowly returned to baseline by 6 hours. Fetal COHb% dropped from 41 ± 11 to 32 ± 11 and remained depressed for 1 hr after the smoke, thus representing an approximate 20% drop in O2carrying capacity. Fetal COHb% rose steadily from 4.8 ± 0.5 and did not peak until 3-6 hr after the smoke at 6.1 ± 1.All three smoke-types caused decreases in maternal and fetal O2Hb%. T appeared to raise COHb higher than M or P.We conclude that smoking decreases O2content in the fetus and speculate that multiple exposures would prolong this O2deficit. The fetus eliminates carbon monoxide much more slowly than the ewe.