Developmental changes in NO bioavailability in fetal erythrocytes

S-nitrosohemoglobin (HbSNO), where hemoglobin (Hb) is nitrosated at Cysbeta93, presumably controls delivery of the vasorelaxant nitric oxide (NO) to hypoxic tissues in an oxygen-sensitive manner. Little is known about how Hb regulates NO bioavailability during fetal development. A study was planned to determine the levels of HbSNO and HbFe(II)NO (NO bound to FeII of heme) in the cord blood of newborn infants of different gestational ages and establish their relationship with the levels of fetal Hb (HbF). Blood samples were collected from umbilical cord obtained from normal newborns between 24 and 41 weeks of gestation. Determinations of HbSNO and HbFe(II)NO were performed using chemiluminescence. The proportion of HbF was determined by HPLC. There were 11 preterm (24-34 weeks of gestation) and 11 term infants (37-41 weeks of gestation). The levels of HbSNO varied from 0.37 to 1.72 x 10(-5) mol/mol heme. There was a significant correlation with gestational age (r2 = 0.46, P = 0.0005) due to the effect of the decrease in the amount of HbF (r2 = 0.81, P < 0.0001). The relationship of HbFe(II)NO was not affected by gestational age or the level of HbF (mean 1.68+/-1.15 x 10(-5) mol/mol heme). Under physiological in utero conditions, fetal erythrocytes have lower levels of HbSNO, which increase in the later stage of fetal development. The levels of HbSNO in the fetal red cell are dependent on the level of adult Hb (HbA). The low HbSNO levels at physiological fetal O2 saturations during early development could protect the fetal circulation from an excess release of NO and O2.     

Phototherapy increases hemoglobin degradation and bilirubin production in preterm infants.

OBJECTIVE: To compare hemoglobin degradation and bilirubin production before and during phototherapy in preterm infants. BACKGROUND: Hemoglobin is catabolized into globin and heme, which is degraded by microsomal heme oxygenase into equimolar carbon monoxide and biliverdin. Biliverdin is then reduced into bilirubin. CO is excreted exclusively by the lungs; therefore, end-tidal carbon monoxide, corrected for inhaled CO (ETCOc), reflects hemoglobin degradation and total bilirubin production. METHOD: A prospective study design was used, including a study group of 24 preterm infants requiring phototherapy. Infants with hemolytic diseases, sepsis, recent blood transfusion, and infants on mechanical ventilation were excluded. ETCOc was measured in preterm infants before and during phototherapy. Hemoglobin degradation and bilirubin production were calculated by measuring ETCOc. RESULTS: The (mean +/- SD) birth weight of 24 preterm neonates was 1975 +/- 613 gm, gestational age was 32.7 +/- 2.3 weeks, hematocrit was 47.5 +/- 6.2 volume%, and peak bilirubin was 13.1 +/- 3.2 mg/dl. First ETCOc measurements were done at 59.6 +/- 22.2 hours of age immediately before starting phototherapy. The second ETCOc measurements were taken at 13.7 +/- 7.9 hours after starting phototherapy. The second measurement of 2.6 +/- 0.6 ppm (mean +/- SD) was significantly higher than the first ETCOc of 2.1 +/- 0.6 ppm (p < 0.05). CONCLUSION: Phototherapy increases hemoglobin degradation and bilirubin production in preterm infants.     

Plasma beta-endorphin concentration in infants with apneic spells

In an attempt to determine whether plasma beta-endorphin (beta-ED) concentrations correlate with occurrence of apnea in preterm infants, measurements were made in three groups of infants. The control group consisted of 11 infants with a mean (+/- SEM) gestational age of 30.5 +/- 0.8 weeks, a mean (+/- SEM) birthweight of 1650 +/- 180 g, and a mean (+/- SEM) postnatal age of 1.3 +/- 0.5 days. Eight infants with apnea, bradycardia, and associated hypotension had a mean (+/- SEM) gestational age, birthweight and postnatal age of 30 +/- 0.9 weeks, 1165 +/- 90 g, and 7.8 +/- 1.9 days, respectively. The third group consisted of eight infants experiencing apnea alone without bradycardia and had a mean (+/- SEM) gestational age, birthweight, and postnatal age of 31 +/- 0.8 weeks, 1380 +/- 125 g, and 2.6 +/- 0.9 days, respectively. The last two groups of infants suffered varying degrees of apnea, but differed in their severity. The plasma endorphin concentrations (+/- SEM) were 26.9 +/- 2, 68.0 +/- 9.0, and 39.6 +/- 2.0 pg/ml, respectively, for the previously described three groups. Significant elevation in beta-ED concentration was observed in the severely apneic infants with bradycardia when compared to the other two groups. The association of increased plasma beta-ED release with severe apneic spells may suggest that these endogenous opiates play a role in the pathophysiology of apnea of prematurity.     

Role of transvaginal sonographic cervical length in predicting spontaneous preterm delivery in triplet pregnancies with therapeutic cerclage

OBJECTIVE: To assess the role of transvaginal sonographic cervical length in predicting spontaneous preterm delivery at < 32 weeks in patients with both triplet pregnancy and therapeutic cerclage. STUDY DESIGN: The maternal records of all triplet pregnancies with therapeutic cerclage and sonographic cervical length before and after cerclage were reviewed (n = 17). Each of these triplet gestations was matched with 2 triplet pregnancies without cerclage based on cervical length after cerclage (+/- 0.5 cm) and gestational age (+/- 3 weeks). Statistical analysis included Fisher's exact test or chi 2 analysis, one-way analysis of variance, logistic regression analysis and receiver operating characteristic curve analysis. RESULTS: Cerclage was placed at a gestational age of 19.0 +/- 3.1 weeks (mean +/- SD) and increased cervical length from 2.0 +/- 0.7 cm to 3.1 +/- 1.4 cm (P < .05). The rate of spontaneous preterm delivery at < 32 weeks was higher among cases than controls (7/17 vs. 4/27, P = .08). Logistic regression analysis demonstrated that only postcerclage cervical length was predictive of spontaneous preterm delivery at < 32 weeks, with a cervical length of 3.3 cm the optimal predictor. CONCLUSION: In women with triplets and therapeutic cerclage, the only significant predictor of spontaneous preterm delivery at < 32 weeks is cervical length after cerclage placement.     

Minor fetal hemoglobins in relation to gestational age

Cord blood samples were obtained at delivery in 44 normal women, at gestational periods ranging from 27 to 41 weeks. All women had a normal glucose screening test and 15 were delivered preterm. With the use of Biorex 70 chromatography, red cell lysates were analyzed to determine the percentages of the different hemoglobin (Hb) components, i.e., HbF1a+b, HbFlc, HbFo, and HbA. The percentage of HbFla+b in fetal blood was higher than the corresponding percentage in adult blood. The percentages and ratios of the various Hb components were compared in preterm and term fetuses and their correlation to gestational age was tested. HbF and HbF/A ratios were higher in preterm fetuses and were negatively correlated with gestational age. HbA and HbA/F ratios were lower in preterm fetuses than in term fetuses and correlated positively with gestational age. The percentages of minor components HbFla+b, and HbFlc were not significantly different in the preterm and the term fetuses, and they did not have statistically significant correlation with gestational age. However, the ratios of these minor hemoglobins to HbF, i.e., HbFla+b/HbF, and HbFlc/HbF and HbFl/HbF were found to be significantly higher in term fetuses as compared to preterm fetuses and to correlate positively with gestational age. This is probably due to the gradual lengthening of the life span of fetal erythrocytes as term approaches, which results in the erythrocytes' increased exposure to the glycolytic intermediates and possibly to glucose.     

Safety and efficacy of long-term tocolysis with indomethacin

Indomethacin was utilized in 24 pregnancies (31 exposed fetuses) in preterm labor who labored despite intravenous tocolysis. The mean gestational age at the start of indomethacin therapy was 25.1 weeks (+/- 4.4), mean duration of indomethacin therapy was 43.9 days (+/- 31.4), mean gestational age at delivery 33.1 weeks (+/- 3.7). Neonatal follow-up revealed the same incidence of complications in these indomethacin-exposed infants, when they were compared with all other infants born in the same time period and exposed to intravenous tocolytics only when matched for gestational age at delivery.     

Perinatal outcome following intravascular transfusion in severely isoimmunized fetuses.

Twenty-six severely isoimmunized pregnancies managed exclusively with ultrasonographically guided intravascular fetal transfusions are reported. The mean gestational age plus and minus one standard deviation (+/- SD) was 26.3 +/- 3.6 weeks and the mean hematocrit (+/- SD) prior to initial transfusion was 20.6 +/- 6.7%. Four of seven hydropic fetuses and 9 of 19 without hydrops were less than or equal to 26 weeks gestation at the first transfusion. Overall survival was 85% (22/26). Survival was similar whether or not fetal hydrops was present (6/7 vs. 16/19) and whether or not the first transfusion was administered at less than or equal to 26 weeks gestation (10/13 vs. 12/13).     

Twin-to-twin transfusion syndrome with hydrops: a retrospective analysis of ten cases

We retrospectively studied 10 cases of twin-to-twin transfusion syndrome (TTTS) with fetal hydrops. TTTS was diagnosed sonographically between the 17-31 weeks of gestation. All twins were delivered by emergency cesarean section because of cardiac decompensation of one or both fetuses. The mean (+/-SD) age at diagnosis was 26.1 +/- 4.5 and the mean age at delivery was 28.8 +/- 2.0 weeks. Gestational age at birth was similar in survivors and nonsurvivors. However, surviving infants were diagnosed later in gestation (23.6 +/- 4.8 vs. 28.7 +/- 1.9 weeks; p < 0.01); and gestational age at appearance of hydrops were later in survivors (26.1 +/- 3.2 vs. 29.2 +/- 2.4 weeks; p < 0.05). Overall survival rate was 50% (10 of 20 infants). All survivors were delivered within 3 days after the appearance of fetal hydropic changes. Extrauterine treatment in earlier stages of TTTS might improve the outcome. Nevertheless, more aggressive intrauterine treatment should be considered in the most severe cases of TTTS developing before 24-25 weeks' gestation.     

Improved oxygenation with prone positioning in neonates: stability of increased transcutaneous PO2.

To evaluate the effect of body position on oxygenation and ventilation in neonates over a prolonged period, infants with respiratory disease were followed by transcutaneous (tc) monitoring for alterations in tcPO2 and tcPCO2 with position changes. In 14 studies of seven patients, prone positioning was compared with supine positioning over a 6-hour interval. All patients were premature, were receiving supplemental oxygen, and had respiratory disease secondary to prematurity. The median gestational age was 29 weeks; all infants were 2 months old or less at the time of the study. Prone positioning resulted in a significantly higher tcPO2; mean (+/- SD) tcPO2 increased from 63 (+/- 11.6) mm Hg to 71 (+/- 14.6) mm Hg, and decreased to 65 (+/- 11.2) mm Hg when the infant was returned to supine (P less than .05). This increase in tcPO2 was stable throughout 2 hours in the prone position. No significant change in tcPCO2 was detected. Infants were also found to spend a greater proportion of time sleeping when prone (75% +/- 13% vs 33% +/- 14%; P less than .05). These finding suggest that improvement in oxygenation with the prone position is stable over an extended period in the sick preterm infant.     

Impact of infertility characteristics and treatment modalities on singleton pregnancies after assisted reproduction

Obstetric and neonatal outcomes of assisted reproduction and control singletons were evaluated after taking into account treatment characteristics and infertility background. The elective single embryo transfer (eSET) group (n = 45) was compared with the compulsory single embryo transfer (cSET; n = 52), double embryo transfer (DET; n = 227) and control (n = 304) groups. Infertility-related prognostic factors for neonatal outcomes were also analysed. Data were collected with structured questionnaires at gestational week 20 and 8 weeks after delivery. Spontaneous onset of delivery was more typical of the eSET group than of cSET and DET groups (68.9 versus 52.0%, P = 0.02). Mean (+/-SD) gestation at birth (39.3 +/- 1.6 weeks) and mean birth weight (3,470 +/- 505 g) of eSET singletons were comparable with other assisted reproduction groups, but gestational duration was lower than in the eSET group than in the control group (39.9 +/- 1.4; P < 0.05). However, numbers of preterm births and low birth weight infants were similar between groups. History of induced abortion increased risk of preterm birth (OR 4.5 and 95% CI 1.2-17.1) in assisted reproduction singletons. A small though clinically unimportant difference in gestational age at birth and birth weight between assisted reproduction and control singletons was found regardless of the number of embryos transferred.     

Outcome of twin-twin transfusion diagnosed before 28 weeks of gestation

To develop prognostic indicators for those patients diagnosed with twin-twin transfusion before 28 weeks' gestation, we conducted a retrospective analysis of all cases diagnosed at Baylor College of Medicine from January 1985 through April 1989. Twenty-seven cases of twin-twin transfusion were diagnosed by ultrasound; the criteria for diagnosis were polyhydramnios in one amniotic cavity and oligohydramnios in the other cavity. The mean (+/- SD) age at diagnosis was 21.9 +/- 2.9 weeks and the mean age at delivery was 26.8 +/- 4.9 weeks. Gestational age at diagnosis was similar in survivors and non-survivors (21.7 +/- 3.7 versus 22.2 +/- 2.8 weeks; P = .35); however, surviving infants were delivered later in gestation (31.9 +/- 3.5 versus 25.9 +/- 3.4 weeks; P = .000008). The overall survival rate was 21%. Fetal hydrops correlated with poor survival. Amniocentesis for decompression and tocolysis failed to decrease perinatal mortality.     

Glycosylated hemoglobin (HbA1), glucose tolerance and neonatal outcome in gestational diabetic and non-diabetic mothers

Glycosylated hemoglobin (HbA1) was determined in three subject groups: 69 non-diabetic mothers who were delivered of normal weight infants at term (Group I), 33 non-diabetic mothers who were delivered of macrosomic infants (greater than 4000 g) at term (Group II), 51 gestational diabetics in the 3rd trimester--before onset of the diabetes therapy (Group III). In all three groups diagnostic assessment of glucose regulation was done by means of the oral glucose tolerance test during the 3rd trimester. Glycosylated hemoglobin was assayed by cation-exchange chromatography in small disposable columns. The mean values and standard deviations of HbA1 were 6.51 +/- 0.46% in Group I, 6.59 +/- 0.42% in Group II and 7.11 +/- 0.56% in Group III. Between the HbA1 values of Group III (gestational diabetes) on the one hand and those of the non-diabetic groups I and II on the other, there were highly significant differences (p less than 0.001; x2-test). HbA1 values above 7.4%--i.e. above mean + 2 s. d. of HbA1 in the non-diabetic mothers--were with 95% probability abnormal and indicative of gestational diabetes. HbA1 values between 7.0% and 7.4% were suspected of impaired glucose tolerance and gestational diabetes respectively. Between the HbA1 levels in the non-diabetic groups and those in the gestational diabetic group there was a vast zone with overlapping values. HbA1 data situated in this transitional area could be found both in non-diabetic subjects and also in those with abnormal glucose regulation. HbA1 values below 6.0% excluded gestational diabetes or otherwise impaired glucose tolerance with a high degree of probability.     

Free carnitine levels in respiratory distress syndrome during the first week of life

Antenatal carnitine administration has been shown to induce fetal lung maturity by increasing pulmonary surfactant in animal and human studies. The aim of this study was to investigate serum free carnitine (FC) levels in preterm infants with respiratory distress syndrome (RDS) and controls during the first week of postnatal life. The study groups consisted of 76 preterm infants with gestational ages ranging from 28 to 36 weeks, and birthweights ranging from 1046 to 2352 g. Serum FC levels were measured in preterm infants (group A, 37 with RDS; group B, 39 controls without RDS) within the first 6 hours after birth, on days 3 and 7. For specific analyses, serum FC levels were determined for gestational ages 28 to 31 weeks and 32 to 36 weeks in both groups. Initial FC levels were decreased insignificantly in group A (22.5 +/- 7.3 micromol/L) compared with group B (23.5 +/- 6.8 micromol/L; P > 0.05). On days 3 and 7 of life, serum FC levels were significantly lower in group A (18.3 +/- 6.1 and 10.2 +/- 3.3 micromol/L, respectively) than in group B (23.4 +/- 7.1 and 22.8 +/- 3.7 micromol/L, respectively; P < 0.05 and P < 0.05, respectively) on days 3 and 7 of life, respectively. Serum FC level remained stable in the non-RDS group ( P > 0.05), but it decreased significantly in the RDS group during the first week of postnatal life ( P < 0.05). No differences were seen between the corresponding gestational age groups. Serum FC levels in RDS infants decreased from days 1 to 7. Decreased neonatal serum carnitine levels in preterm infants with RDS during the first week of life might be caused by increasing consumption of carnitine in lung tissue for surfactant synthesis.     

Efficacy of a single dose of antenatal corticosteroids on morbidity and mortality of preterm infants

OBJECTIVE: To assess the effectiveness of an incomplete course of antenatal corticosteroids (ACS) on neonatal morbidity and mortality of preterm infants. METHODS: Preterm infants born at 25-34 weeks' gestational age between January 1, 1998 and December 31, 2003 were included in this study. Studied infants were divided in two groups: the ACS group included those infants who had been exposed to a single 12-mg dose of betamethasone before delivery while the control group included those infants who had been delivered without any antenatal corticosteroids treatment. The most important neonatal outcomes were compared between the two groups. RESULTS: One hundred and seventy neonates (41.4%) were exposed to one 12-mg dose of betamethasone before delivery, while 241 neonates (58.6%) did not receive any antenatal corticosteroids treatment. Mean gestational age at delivery (30.4+/-2.4 weeks versus 31.2+/-2.9 weeks, p=0.004) and mean birth weight (1375+/-454 g versus 1625+/-580 g, p<0.001) were lower in the ACS group. The univariate analysis showed that delivery room intubation and respiratory distress syndrome were more frequent in the ACS group and that the length of stay was also significantly longer in this group. No differences were found concerning survival, neonatal morbidity, need for and duration of mechanical ventilation and oxygen therapy. The incidence of major outcomes in survivors was also similar. Logistic regression adjusted for gestational age showed that the exposure to a single dose of betamethasone before delivery was not associated with a significant reduction in the rate of any neonatal outcome. We also compared the outcomes in function of gestational age subclasses. In the 25-27 weeks subgroup, delivery room intubation, surfactant treatment and patent ductus arteriosus (PDA) were less frequent in ACS infants; they had also shorter ventilation and oxygen duration. In the 30-31 weeks subgroup, ACS infants had a lower incidence of mechanical ventilation and a shorter duration of oxygen therapy. Finally, no differences were found in the 28-29 weeks subgroup and in the 32-34 weeks subgroup. CONCLUSION: Effects of incomplete antenatal corticosteroids are variable: they give some benefits to infants of 25-27 weeks gestational age, fail to show any difference in outcomes in the 32-34 weeks subgroup and are doubtful between these extremes.     

High-frequency oscillatory ventilation in term and near-term infants with acute respiratory failure: early rescue use

This study describes a high-frequency oscillatory ventilation (HFOV) protocol for term and near-term infants with acute respiratory failure (ARF) and reports results of its prospective application. Neonates, with gestational age >or= 34 weeks, were managed with HFOV, if required, on conventional ventilation (CV), a fraction of inspired oxygen (F IO(2)) 0.5, and a mean airway pressure > 10 cm H (2)O to maintain adequate oxygenation or a peak inspiratory pressure > 24 cm H (2)O to maintain tidal volume between 5 and 7 mL/kg of body weight. Seventy-seven infants (gestational age, 37 +/- 2,3 weeks), received HFOV after a mean duration of CV of 7.5 +/- 9.7 hours. Arterial blood gases, oxygenation index (OI), and alveolar-arterial difference in partial pressure of oxygen (P AO(2) - Pa O(2)) were recorded prospectively before and during HFOV. There were a rapid and sustained decreases in mean airway pressure (MAP), F IO(2), OI, and P AO(2) - Pa O(2) during HFOV ( P 相似文献   

Glycosylated hemoglobin: a sensitive indicator of gestational diabetes

Previous studies suggested that the assessment of hemoglobin A1 (HbA1) concentration was a poor indicator of diabetes in pregnancy. However, HbA1 was measured by ion exchange chromatography, which is subject to spurious alterations. To reevaluate the use of glycosylated hemoglobin concentration (GlyHb) as an indicator of gestational diabetes, 64 women at 10 to 15 weeks' gestation were studied by measuring GlyHb by a specific affinity chromatography assay, and blood glucose concentration was determined one hour post a 50-g oral glucose load. Gestational diabetes developed in 15 women in whom GlyHb (7.4 +/- 0.2%) was greater than in normal pregnant women (5.7 +/- 0.1%, P less than .001). If a GlyHb of 6.3% were chosen as the threshold for diagnostic evaluation for diabetes, only 6.7% of the gestational diabetics would have missed diagnosis. Of normal women, 14.2% would have been subjected to glucose tolerance test. GlyHb elevation was associated with the birth of infants large for gestational age. The assessment of GlyHb by affinity chromatography between 10 and 15 weeks' gestation may be a sensitive predictor of patients who will develop gestational diabetes.     

Subsequent pregnancy following labor of a very-low-birth-weight infant

During a period of 5 years (1978-1982), 55 mothers with an average age of 27.5 +/- 5.4 years, delivered 59 infants, weighing less than 1500 g. These infants had a mean birth weight of 1160.5 +/- 263 g and a mean gestational age of 28.7 +/- 2.25 weeks (range 25-32 weeks). Subsequently 47 (79.6%) survived and 12 (20.4%) died. There was a statistical difference of both mean gestational age and of mean gestational weight between survivors or infants with neonatal death. Twenty two of 29 mothers who subsequently became pregnant, gave birth to liveborn infants, who subsequently survived (four pregnancies terminated in induced abortion). Mean gestational age was 37 +/- 3 weeks (range 32-41 weeks) (P less than 0.001) and a mean birth weight was 2753.2 +/- 570 g (range 1620-3600 g) (P less than 0.001. All the 22 infants subsequently born weighed more than 1501 g, 7 (31.8%) infants weighed 1501-2500 g and 15 (68.2%) more than 2500 g. Similar data were obtained from a control group of 615 mothers (chosen at random) who delivered a normal infant at term, 202 subsequently became pregnant and 176 gave birth to a normal infant at term. Mean gestational age was 39.54 +/- 1.24 weeks (P less than 0.001) and mean birth weight was 3299.3 +/- 412 g (P less than 0.001). (In the control group 10 pregnancies terminated in induced abortions). The above data could be used in advising for future pregnancy outcome in regard to women with premature births.     

Integrated backscatter of the brain of preterm infants

We measured integrated backscatter (IBS) in the brain of preterm infants using acoustic ultrasound. The study group consisted of 25 preterm infants (gestational age, 32.4+/-2.5 weeks; birth weight, 1488+/-422 g). In parasagittal scans through the posterior horn of the lateral ventricle, regions of interest (ROI) were positioned in the cerebral white matter near the posterior horn (P), anterior horn (A) of the lateral ventricle, and the thalamus (T). IBS of the ROI was measured and IBS of P minus T (P-T) and IBS of A minus T (A-T) were calculated. A-T was greater than P-T. A-T and P-T decreased with increasing gestational age and birth weight. These changes may represent maturation of the cerebrum. A-T or P-T may be useful parameters of cerebral tissue characterization.     

Late hyporegenerative anemia in neonates with rhesus hemolytic disease.

This study was conducted to determine the risk factors of the late hyporegenerative anemia in Rh-isoimmunized infants. Data on 36 infants with rhesus hemolytic disease were analyzed. The mean gestational age and birth weight were 36 +/- 1.3 weeks and 2837 +/- 403 grams respectively. Twenty-seven infants (75%) received between 2 and 8 intravascular intrauterine blood transfusions. Fourteen infants (39%) required simple packed red blood cell transfusions and 11 infants (31%) required exchange blood transfusion in the immediate postnatal period. Thirty infants (83%) developed late anemia and required blood transfusions at a mean postnatal age of 43.3 +/- 15.7 days. Sixty-four percent of infants who had exchange blood transfusions did not develop late anemia, while 92% of infants who did not require exchange blood transfusion developed late anemia, and the difference was statistically significant (P = 0.035). Serum erythropoietin levels were determined in 8 infants immediately before simple transfusion for late anemia. The media serum erythropoietin level was 21.2 mU/ml, ranging between less than 10 to 114.2 mU/ml. We conclude that late hyporegenerative anemia is common among Rh isoimmunized infants, regardless of the intravascular intrauterine transfusion. Exchange blood transfusion was associated with less occurrence of late anemia.     

Pregnancy prolongation in triplet pregnancies. Oral vs. continuous subcutaneous terbutaline.

OBJECTIVE: To assess gestational gain in triplet pregnancies treated with oral terbutaline followed by treatment with continuous subcutaneous terbutaline. STUDY DESIGN: From a database of patients who received perinatal home care services, we identified women with triplet gestations first receiving daily oral terbutaline following an episode of threatened preterm labor who subsequently received continuous subcutaneous terbutaline infusion after recurrence of preterm contractions. The primary outcome studied was gestational gain with oral terbutaline vs. gestational gain with continuous subcutaneous terbutaline infusion. RESULTS: One hundred four women were studied. The mean gestational age at enrollment was 22.0 +/- 2.7 weeks. Significantly more gestational gain was achieved during subcutaneous tocolytic treatment than during oral treatment (mean 5.4 +/- 3.4 vs. 2.8 +/- 2.2 weeks, P < .001). Twenty-nine percent of desired prolongation was achieved with oral terbutaline, while 71% of desired prolongation was achieved with subcutaneous terbutaline infusion (P < .001). The mean gestational age at delivery was 33.2 +/- 2.2 weeks. CONCLUSION: Gestational gain was greater in triplet pregnancies during treatment with continuous subcutaneous terbutaline infusion than with oral terbutaline.