Predominance of L-dopa in fetal plasma and the amniotic fluid during late gestation in the rat

The purpose of this study was to reevaluate catecholamine distribution in fetal and maternal compartments during late gestation in the rat. Fetal and maternal plasma and amniotic fluid were collected from anesthetized rats on consecutive days from day 17 to day 22, the day of parturition. The fluid was analyzed for dihydroxyphenylalanine (L-dopa), dopamine, norepinephrine, and epinephrine by radioenzymatic assays. Amniotic fluid volume was determined by a direct weighing method. L-Dopa concentrations constituted approximately 50% of total fetal plasma catecholamines and were significantly higher in fetal than in maternal circulation. Dopamine concentrations in fetal plasma were tenfold lower than those of L-dopa but were also significantly higher in fetal than in maternal plasma; norepinephrine levels were similar in both. Maternal plasma epinephrine levels remained relatively constant, whereas fetal epinephrine levels increased fiftyfold from day 17 to day 22. L-Dopa concentrations in the amniotic fluid were tenfold higher than those of dopamine, and the concentrations of both increased markedly during the last 2 days of gestation. However, this apparent rise could be attributed to the concomitant fivefold reduction in the amniotic fluid volume observed at this time. It is concluded that L-dopa is the predominant catecholamine in both the fetal plasma and the amniotic fluid during late gestation in the rat. At the present time, neither the source nor the possible physiologic functions of L-dopa during fetal life are known.     

The spontaneously hypertensive rat fetus, not the mother, is responsible for the reduced amniotic fluid PTHrP concentrations and growth restriction

Intrauterine parathyroid hormone-related protein (PTHrP) concentrations are reduced in association with growth restriction in the spontaneously hypertensive rat (SHR) compared to those of its normotensive control, the Wistar Kyoto (WKY) rat, implicating PTHrP as a pivotal fetal growth factor. The aim of this study was to examine, by embryo cross-transplanation between SHR and WKY, whether the mother, fetus, or both, are responsible for the suppressed SHR amniotic fluid PTHrP. One-day-old SHR embryos were gestated in either an SHR (SHR-in-SHR) or WKY (SHR-in-WKY) surrogate, similarly one-day-old WKY embryos were gestated in either an SHR (WKY-in-SHR) or WKY (WKY-in-WKY) mother. At 20 days gestation, maternal plasma and amniotic fluid samples were collected and assayed for PTHrP concentrations. Data were analysed by two-way ANOVA (mean+/-sem, n=5-9 mothers/group). There were no differences in litter number or maternal plasma PTHrP concentrations. Fetal weight (P< 0.009), fetal/placental weight ratio (P< 0.004) and amniotic fluid PTHrP concentrations (P< 0.001) were lower and amniotic fluid volume (P< 0.0001) was higher with an SHR fetus compared to the WKY fetus irrespective of maternal strain. Thus, the SHR fetus is growth restricted and has suppressed amniotic fluid PTHrP, which are largely determined by the fetus or gestational tissues and are independent of maternal hypertension or maternal PTHrP. We suggest that the low SHR amniotic fluid PTHrP may play a role in the development of SHR growth restriction.     

Drug accumulation in lung fluid of the fetal lamb after maternal or fetal administration

The pharmacokinetic characteristics of the antiemetic drug metoclopramide and the antihistamine diphenhydramine have been determined in a chronically catheterized pregnant sheep preparation. Metoclopramide and diphenhydramine were administered by separate maternal and fetal intravenous infusions to a steady state as well as by maternal intravenous bolus dosing. Drug concentrations in the maternal and fetal plasma and the amniotic and tracheal fluids were measured by means of capillary gas-liquid chromatographic assay techniques. Both metoclopramide and diphenhydramine were excreted into tracheal fluid in substantial quantities. Tracheal metoclopramide concentrations were found to exceed fetal plasma levels by about fifteen-fold while diphenhydramine attained maximal excretion in tracheal fluid of about five times that seen in fetal plasma. Drug levels were observed to accumulate slowly in amniotic fluid and eventually to exceed tracheal concentrations. The markedly elevated concentrations of these drugs in fetal lung fluid suggests that the fetal lung may be an important route of drug distribution, elimination, and excretion.     

Oxytocin levels in maternal and fetal plasma,amniotic fluid,and neonatal plasma and urine

Summary Oxytocin was measured in maternal and fetal plasma, amniotic fluid and neonatal plasma and urine using a specific radioimmunoassay, following extraction procedures with Florisil. Maternal oxytocin levels rose progressively with advancing gestation, but there were no significant differences between oxytocin levels around the onset of labor. No diurnal rhythm of oxytocin was evident in maternal plasma during the third trimester. Maternal and umbilical plasma oxytocin levels at spontaneous delivery were significantly higher than those at elective cesarean section. Maternal oxytocin levels in four cases of post-term delivery were lower than those during normal late pregnancy; all four cases exprerienced uterine inertia. All amniotic fluid samples had detectable oxytocin levels and there were no significant differences between oxytocin levels in the second trimester and those in the third trimester. Oxytocin levels in neonatal urine were higher than levels in amniotic fluid and lower than in the umbilical artery. Neonatal plasma oxytocin levels gradually decreased and oxytocin levels of 7-day-old infants were significantly lower than those in the umbilical artery, but higher than those in adults. In conclusion, it appears that maternal oxytocin levels may not be involved in triggering the onset of labor but may play a role in the maintenance and reinforcement of labor.     

Maternal-fetal transfer and amniotic fluid accumulation of lamivudine in human immunodeficiency virus-infected pregnant women

OBJECTIVE: The purpose of this study was to investigate placental transfer and amniotic fluid concentrations of lamivudine in human immunodeficiency virus-infected women who received the agent during pregnancy. STUDY DESIGN: Mothers in the study were receiving antiretroviral therapy that included lamivudine in a clinical setting. Maternal blood, cord blood, and amniotic fluid samples were obtained simultaneously at the time of delivery from 57 mother-infant pairs. RESULTS: At a median of 8.5 hours after the last maternal oral 150-mg dose of lamivudine, median maternal and fetal plasma concentrations were 302 and 240 ng/mL, respectively. Individual maternal and fetal concentrations were strongly correlated (r2 = 0.36; P < 10(-4)), and their median ratio was about 1. The median concentration in the amniotic fluid was 5 times higher than that in maternal plasma (upper range of ratio, 133). CONCLUSION: Lamivudine appeared to cross the placenta by simple diffusion and is concentrated in the amniotic fluid. High amniotic fluid levels of lamivudine may carry both benefits and risks for the child.     

Prolactin-releasing system in maternal, fetal, and amniotic compartments during labor

The effect of a dopamine antagonist on prolactin concentrations was studied in maternal, fetal plasma, and amniotic fluid in term gestation. Twenty-three women with normal full-term pregnancies received 10 mg metoclopramide intravenously during labor. The prolactin levels in maternal plasma increased significantly after metoclopramide. However, the prolactin levels in amniotic fluid and fetal plasma did not change significantly after administration of this drug. Although the increased values of prolactin in maternal plasma were significantly correlated with metoclopramide concentrations after metoclopramide injection, there was no correlation between these two values in amniotic fluid. The authors conclude that the prolactin-releasing system in amniotic fluid is independent of the maternal hypothalamopituitary axis.     

Amino acid variations in amniotic fluid and maternal plasma from Rh-sensitized pregnancies. II

Amino acids were quantitated by ion-exchange chromatography in amniotic fluid and maternal plasma from Rh-sensitized pregnancies. Twenty-four patients of 34 to 40 weeks' gestation were studied, and results were compared to those in normal pregnancy. Significant differences were found for amino acid concentrations in amniotic fluid and maternal plasma from those patients in whom fetal death occurred. When the fetus survived, amino acid levels were similar to normal levels. In particular, it was noted that proline levels were markedly elevated in the amniotic fluid of patients in whom fetal death occurred (p < 0.001). From this preliminary work arises the interesting possibility that an increased amniotic fluid versus maternal plasma proline level may be of diagnostic assistance in severe Rh disease.     

Maternal and fetal renin activity and renin and big renin concentrations in second-trimester pregnancy.

Plasma renin activity (PRA) and the concentrations of renin (PRC) and big renin (PBRC) have been determined in maternal and fetal blood, and renin and big renin have been measured in amniotic fluid, at 16 to 20 weeks of gestation. Gradients between peripheral arterial and venous and uterine venous maternal circulation were not apparent for PRA, PRC, or PBRC. PRC and PBRC but not PRA were consistently higher in fetal cord blood than in the maternal compartment. The concentrations of big renin and of renin were tenfold higher in amniotic fluid than in maternal plasma and were significantly correlated in amniotic fluid but not maternal or fetal plasma.     

Fetal death: A condition with a dissociation in the concentrations of soluble vascular endothelial growth factor receptor-2 between the maternal and fetal compartments

Objective.?An anti-angiogenic state has been implicated in the pathophysiology of preeclampsia, fetal growth restriction and fetal death. Vascular endothelial growth factor (VEGF), an indispensible angiogenic factor for embryonic and placental development exerts its angiogenic properties through the VEGF receptor (VEGFR)-2. A soluble form of this protein (sVEGFR-2) has been recently detected in maternal blood. The aim of this study was to determine if fetal death was associated with changes in the concentrations of sVEGFR-2 in maternal plasma and amniotic fluid.

Study Design.?Maternal plasma was obtained from patients with fetal death (n?=?59) and normal pregnant women (n?=?134). Amniotic fluid was collected from 36 patients with fetal death and the control group consisting of patients who had an amniocentesis and delivered at term (n?=?160). Patients with fetal death were classified according to the clinical circumstances into the following groups: (1) unexplained; (2) preeclampsia and/or placental abruption; (3) chromosomal and/or congenital anomalies. Plasma and amniotic fluid concentrations of sVEGFR-2 were determined by ELISA. Non-parametric statistics and logistic regression analysis were applied.

Results.?(1) Patients with a fetal death had a significantly lower median plasma concentration of sVEGFR-2 than normal pregnant women (p?<?0.001). The median plasma concentration of sVEGFR-2 in patients with unexplained fetal death and in those with preeclampsia/abruption, but not that of those with congenital anomalies, was lower than that of normal pregnant women (p?=?0.006, p?<?0.001 and p?=?0.2, respectively); (2) the association between plasma sVEGFR-2 concentrations and preterm unexplained fetal death remained significant after adjusting for potential confounders (OR: 3.2; 95% CI: 1.4–7.3 per each quartile decrease in plasma sVEGFR-2 concentrations); (3) each subgroup of fetal death had a higher median amniotic fluid concentration of sVEGFR-2 than the control group (p?<?0.001 for each); (4) the association between amniotic fluid sVEGFR-2 concentrations and preterm unexplained fetal death remained significant after adjusting for potential confounders (OR: 15.6; 95% CI: 1.5–164.2 per each quartile increase in amniotic fluid sVEGFR-2 concentrations); (5) among women with fetal death, there was no relationship between maternal plasma and amniotic fluid concentrations of sVEGFR-2 (Spearman Rho: 0.02; p?=?0.9).

Conclusion.?Pregnancies with a fetal death, at the time of diagnosis, are characterized by a decrease in the maternal plasma concentration of sVEGFR-2, but an increase in the amniotic fluid concentration of this protein. Although a decrease in sVEGFR-2 concentration in maternal circulation depends upon the clinical circumstances of fetal death, an increase in sVEGFR-2 concentration in amniotic fluid seems to be a common feature of fetal death. It remains to be determined if the perturbation in sVEGFR-2 concentrations in maternal and fetal compartments observed herein preceded the death of a fetus.     

Transfer and dynamics of uric acid in the pregnant rhesus monkey. II. A mathematical model.

The objective of the present study was to develop a mathematical model of the dynamics of uric acid between fetal and maternal compartments in the term pregnant rhesus monkey. In 3 different animals 14C-labeled uric acid was injected into the fetal circulation, the amniotic fluid and the maternal circulation, respectively. In one experiment no uric acid was administered and the fetus was deliberately killed at the beginning of the experiment. Samples of fetal and maternal blood, maternal urine and amniotic fluid were collected at regular intervals. Semilogarithmic time-activity curves were constructed and time constants were determined. An open four-compartment model (fetal-placental plasma, fetal-placental interstitial space, amniotic fluid and maternal plasma) was applied to describe the intercompartmental dynamics of uric acid. Transplacental clearance was approx. 1 ml X min-1 in both directions, maternal renal clearance was about 17 ml X min-1. These results and the calculated values of the other intercompartmental clearances support earlier results, obtained with the steady infusion method. Uric acid concentrations in amniotic fluid and fetal plasma appeared to increase significantly during the experiments. The rise in amniotic fluid levels can only be explained by accepting a yet undefined compartment in which uric acid is produced and cleared directly into the amniotic cavity. It is speculated that this additional compartment could be the fetal lung.     

孕期接触褪黑素对细菌脂多糖引起的小鼠炎性细胞因子释放的影响

目的:研究孕期接触褪黑素(MT)对细菌脂多糖(LPS)引起小鼠炎性细胞因子释放的影响。方法:孕17d鼠被随机分为对照组、LPS组和MT+LPS组,每组12只。LPS组、MT+LPS组孕鼠均给予LPS(500μg/kg,i.p.);MT+LPS组在LPS处理前0.5h给予MT(5mg/kg,i.p.);对照组孕鼠给予等容积生理盐水。于LPS或生理盐水处理1.5h后摘眼球取血,处死孕鼠,并留取羊水、胎肝、胎脑。用ELISA法分别测定母血、羊水、胎肝和胎脑中TNF-α、IL-1β、IL-6及IL-10含量。结果:LPS能显著升高母血、羊水和胎肝中TNF-α、IL-1β、IL-6及IL-10含量,MT+LPS组母血和胎肝中IL-10含量明显高于LPS组,MT预处理显著抑制LPS引起的母血TNF-α释放,但MT对LPS引起的母血和羊水中IL-1β、IL-6含量的变化无明显影响。此外,LPS显著升高胎脑中TNF-α和IL-10含量,而MT预处理却明显降低LPS引起的胎脑TNF-α释放。结论:孕期接触MT可多向调节LPS诱发的小鼠母血、羊水、胎肝和胎脑中促炎细胞因子与抗炎细胞因子释放。     

Brain natriuretic peptide and endothelin-1 in the pathogenesis of polyhydramnios-oligohydramnios in monochorionic twins

OBJECTIVE: We investigated the association between amniotic fluid levels of human brain natriuretic peptide, endothelin-1, and abnormal amniotic fluid volume in monochorionic twins with and without chronic twin-twin transfusion syndrome. STUDY DESIGN: Amniotic fluid and fetal blood samples were obtained in utero or at cesarean delivery from monochorionic twins with (n = 20) or without chronic twin-twin transfusion syndrome (n = 10). Concentrations of atrial natriuretic peptide, human brain natriuretic peptide, and endothelin-1 (in picograms per milliliters) were determined by radioimmunoassay. RESULTS: The amniotic fluid concentrations of human brain natriuretic peptide (P <.001) and endothelin-1 (P <.001) in the recipient fetuses were higher than the donor twins but were similar in the twins with no twin-twin transfusion syndrome. In the donor twins, amniotic fluid concentrations of human brain natriuretic peptide (P <.001) and endothelin-1 (P <.001) were lower than the twin pairs with no twin-twin transfusion syndrome. In both chronic twin-twin transfusion syndrome fetuses (P <.01) and fetuses with no twin-twin transfusion syndrome (P <.001), the amniotic fluid concentrations of human brain natriuretic peptide were high, although the concentrations of the endothelin-1 were lower than the fetal plasma concentrations. A positive association was present between amniotic fluid levels of human brain natriuretic peptide and endothelin-1 (R (2) = 0.51, P <.001, n = 60). Amniotic fluid human brain natriuretic peptide (r = 0.67, P <.001) and endothelin-1 (r = 0.57, P <.01) levels of the recipient twins correlated with the amniotic fluid index. CONCLUSION: These data suggest that amniotic fluid concentrations of human brain natriuretic peptide and endothelin-1 were highest in the twins with polyhydramnios and lowest in the twins with oligohydramnios, which suggests the importance of these hormones in the regulation of amniotic fluid volume.     

The effect of continuous morphine administration on maternal plasma oxytocin concentration and uterine contractions after open fetal surgery.

OBJECTIVE: A major complication of open fetal surgery is prematurity. We propose that fetal and maternal stress/pain after surgery may affect the concentration of circulating oxytocin and the frequency of uterine contractions, thus increasing the risk of preterm delivery. The objective of this study was to test whether continuous morphine sulfate administration after open fetal surgery has an effect on maternal plasma oxytocin concentration and the frequency of uterine contractions. METHODS: An established time-pregnant primate model for open fetal surgery was used. From the time of surgery until the end of the three-day study period, three animals received prophylactic antibiotics, a bolus of indomethacin, and a bolus of morphine sulfate (group I). Three other animals received the same prophylactic antibiotics and an i.v. bolus of indomethacin, as well as a continuous i.v. infusion of morphine sulfate throughout the entire study period (group II). Maternal blood samples were collected to determine oxytocin plasma concentrations. Oxytocin was measured by radioimmunoassay. Uterine activity was continuously recorded through an amniotic fluid catheter and quantified as number of contractions (10 mmHg increase from base line in intrauterine pressure) per hour (UCs/h). RESULTS: The mean maternal plasma oxytocin concentration was higher (p < 0.01) and the number of uterine contractions more frequent (p < 0.05) in the group of animals with intermittent doses of morphine than in the group that received morphine continuously. CONCLUSIONS: These data suggest that maternal plasma oxytocin concentration and uterine activity after open fetal surgery may be related to inadequate maternal/fetal analgesia/sedation.     

The effect of labor on maternal and fetal vitamins C and E

OBJECTIVE: This study was conducted to compare maternal and fetal plasma, amniotic fluid, and chorioamnion levels of vitamins C and E in term (>38 weeks' gestation) subjects undergoing elective repeat cesarean section (CS) without labor with values of subjects of similar gestational age and dietary intake undergoing labor and vaginal delivery (VD). STUDY DESIGN: Healthy women undergoing elective repeat CS (n = 5) or uncomplicated VD (n = 5) at term (>38 weeks' gestation) were studied. For CS patients, maternal and fetal (cord) blood, amniotic fluid, and chorioamnion samples were collected at time of surgery. For VD patients, maternal blood and amniotic fluid were obtained at 5 cm cervical dilation and fetal cord blood and chorioamnion were collected at delivery. Each patient completed a nutritional questionnaire. Plasma and membrane vitamin E concentrations were determined by reversed-phase high-performance liquid chromatography and standardized to cholesterol or membrane protein, respectively. Vitamin C was determined with the use of the 2,4-DNPH method. RESULTS: Dietary intakes for vitamins C and E as well as maternal and fetal vitamin E plasma concentrations were similar for CS and VD patients. In both groups, maternal levels were higher than fetal levels(P <.05). Chorioamnion membrane vitamin E measurements in both groups were similar. Vitamin C concentrations in CS and VD patients were highest in amniotic fluid, lower in fetal plasma, and lowest in maternal plasma. However, mean vitamin C concentrations in maternal plasma, amniotic fluid, and fetal plasma of VD patients were significantly lower, being only 20% +/- 6%, 29% +/- 11%, and 22% +/- 2% of values obtained from CS patients. CONCLUSION: During labor in healthy women at term, uterine contractile activity may generate reactive oxygen species (ROS) through the process of repetitive ischemia and reperfusion. With the significant depletion of vitamin C during labor, we speculate that water-soluble vitamin C scavenges ROS in the aqueous phase and recycles lipid-soluble vitamin E to combat ROS-induced tissue damage.     

Feto-maternal concentrations of diazepam and W-demethyldiazepam after intra-amniotic diazepam injection.

Ten milligrams of diazepam were injected intraamniotically in 8 mothers prior to therapeutic abortion between 12 and 19 weeks. The diazepam concentrations in the maternal plasma were comparable to those found after the same intramuscular diazepam dose to the mother. The concentration of diazepam in the amniotic fluid 12 to 18 hours after the injection was no longer significantly higher than in the maternal plasma. The concentrations of diazepam in the fetal plasma, liver and brain were comparable to the concentrations resulting from a 10 mg intramuscular diazepam dose to the mother about 2 hours before legal abortion. The feto-maternal ratio of diazepam was of same magnitude as after the intramuscular application to the mother. The results indicate that the disappearance of diazepam from the amniotic fluid in this stage of pregnancy occurs extraplacentally, through the mambranes into the uterine circulation. In the treatment of a fetus with drugs having properties similar to diazepam, intra-amniotic administration is no better than intramuscular administration to the mother.     

Role of fetal catecholamines before and during birth

It is true that developing fetus in uterus may be mostly influenced by maternal conditions. However, there is little evidence to prove the existence of nervous connection between fetus and mother. The biochemical and physiological phenomena of fetus in utero may be controlled mainly by fetal autonomy with nutritional supply from mother. The sympathoadrenal system of fetus has received much attention with the technical progress of catecholamine assays. Fetal plasma catecholamine concentrations during birth are remarkably higher than those in adult life. The function of those high catecholamine concentrations has been shown to control fetal circulation during hypoxia, to maintain glucose supply to the heart and brain, and to prepare the lung for ventilation. So it may be said that fetal plasma catecholamine surge at birth is essential to neonatal adaptation. Amniotic fluid catecholamines and their metabolites were higher in intrauterine growth retarded fetus, which consumed own catecholamine reserve in adrenal medulla before parturition. It is possible to estimate the fetal condition by measuring the concentration of catecholamines and their metabolites in amniotic fluid. The amniotic norepinephrine, epinephrine and particularly dopamine concentration has been found to increase toward term. The rise in dopamine has been assumed to stimulate intrauterine synthesis of prostaglandins. We demonstrated that L-dopa was metabolized to dopamine in fetal kidney and that dopamine in amniotic fluid was originated from fetal urine.     

Effects of maternal antioxidant supplementation on maternal and fetal antioxidant levels: a randomized, double-blind study

OBJECTIVE: We sought to determine whether vitamins C and E could be delivered to the fetal-placental unit through maternal oral supplementation. STUDY DESIGN: In a randomized, double-blind study, 20 women received a daily prenatal vitamin with or without 400 IU of vitamin E and 500 mg of vitamin C, starting at 35 weeks' gestation. At randomization, a nutritional questionnaire, plasma vitamin C and E and red blood cell (RBC) vitamin E levels were determined. At delivery, concentrations of maternal and fetal plasma vitamin C and E, maternal and fetal RBC vitamin E, amniotic fluid vitamin C, and chorioamnion vitamin E and tensile strength were determined. RESULTS: Maternal plasma vitamin E levels increased in the supplemented women but not in the control subjects. No changes in maternal vitamin C levels were noted. Maternal plasma vitamin C concentrations at delivery correlated closely with amniotic fluid vitamin C levels. Similarly, maternal plasma vitamin E levels at delivery correlated with the chorioamnion concentration of vitamin E. CONCLUSIONS: Maternal plasma vitamin E levels are increased by oral supplementation. Maternal plasma vitamin C and E concentrations correlate with the concentration of vitamin C in the amniotic fluid and vitamin E in the chorioamnion, respectively.     

Renal effects of ovine fetal arginine vasopressin secretion in response to maternal hyperosmolality

Acute increases in maternal plasma osmolality can increase amniotic fluid osmolality. Amniotic fluid is primarily derived from fetal urine production, and arginine vasopressin infusion can affect both fetal urine production and amniotic fluid osmolality. To assess the effect of short-term changes in maternal osmolality on fetal arginine vasopressin secretion and renal function, six ewes of 126 +/- 1 days' gestation received intravenous infusions of 20% mannitol (500 ml/10 min). In response to mannitol infusion, both maternal and fetal plasma osmolality increased significantly (302 +/- 3 to 326 +/- 2 and 300 +/- 1 to 309 +/- 2 mosm, respectively). Increased fetal plasma and urine arginine vasopressin concentrations were associated with significant increases in fetal urine osmolality (146 +/- 12 to 262 +/- 30 mosm) and sodium concentration (35.8 +/- 2.8 to 76.5 +/- 20 mu Eq/ml), but fetal urine production rates did not change (0.68 +/- 0.11 to 0.62 +/- 0.15 ml/min). These conclusions were reached: Acute increases in maternal osmolality can affect fetal arginine vasopressin secretion; arginine vasopressin-induced increases in fetal urine osmolality may contribute to increased amniotic fluid osmolality in response to maternal hyperosmolality.     

Disposition of ethanol in maternal blood,fetal blood,and amniotic fluid of third-trimester pregnant ewes

The disposition of ethanol in maternal arterial blood, fetal arterial blood, and amniotic fluid of nine conscious, cannulated pregnant ewes (128 to 137 days' gestation) was determined for 1-hour maternal intravenous infusion of ethanol, 1 gm/kg maternal body weight. The maternal arterial blood and fetal arterial blood ethanol concentration-time curves were virtually superimposable up to 14 hours. The apparent zero-order ethanol elimination rates for maternal arterial blood and fetal arterial blood were similar. There was a time lag in the transfer of ethanol into amniotic fluid relative to fetal arterial blood, and the peak ethanol concentration in amniotic fluid was significantly lower than the concentrations in maternal arterial blood and fetal arterial blood. The apparent zero-order ethanol elimination rate for amniotic fluid was slower, but not significantly so, compared with the ethanol elimination rates for maternal arterial blood and fetal arterial blood. Ethanol-derived acetaldehyde was found in maternal arterial blood, fetal arterial blood, and amniotic fluid at concentrations at least 1000-fold lower than the respective ethanol concentrations. The data indicate that, for administration of this ethanol dosage regimen to the third-trimester pregnant ewe, there is rapid, bidirectional placental transfer of ethanol; elimination of ethanol from the fetus is regulated primarily by maternal elimination of ethanol; the amniotic fluid may serve as a reservoir for ethanol in utero; and there is appreciable acetaldehyde-metabolizing capacity.     

Effect of prenatal betamethasone administration on maternal and fetal corticosteroid-binding globulin concentrations

OBJECTIVE: This study was undertaken to examine the effects of prenatal betamethasone administration on corticosteroid-binding globulin concentrations in maternal and fetal plasma and amniotic fluid. STUDY DESIGN: Two groups of patients with preterm labor at 24 to 35 weeks' gestation who were receiving prenatal betamethasone (2 intramuscular doses of 12 mg) were studied. Maternal plasma was obtained before and at variable intervals until 1 week after betamethasone administration. Umbilical cord blood and amniotic fluid samples were collected at the time of delivery. Samples were also collected from patients at risk for preterm delivery who did not receive glucocorticoids. RESULTS: Betamethasone suppressed maternal cortisol concentration by >70% within 24 hours of injection but did not significantly alter corticosteroid-binding capacity or relative concentrations of corticosteroid-binding globulin isoforms in either maternal or umbilical cord plasma. Betamethasone reduced corticosteroid-binding capacity in amniotic fluid within 24 hours of injection, and values remained suppressed 1 week after treatment. CONCLUSION: Maternal and fetal plasma corticosteroid-binding globulin concentrations were unchanged after maternal betamethasone administration at 24 to 32 weeks' gestation but amniotic fluid corticosteroid-binding globulin concentrations decreased significantly, suggesting different sites of either corticosteroid-binding globulin production or regulation or both.