Intrapartum management of nonvertex second-born twins: a critical analysis.

OBJECTIVE: Our purpose was to assess the impact of the mode of delivery--vaginal delivery versus cesarean section--on the perinatal outcomes of the second-born breech twins. STUDY DESIGN: This study was a retrospective analysis of second-born breech twins with a gestational age of > or =24 weeks at the onset of labor. The patients are divided into three groups: cesarean section without labor (group I), cesarean section after labor (group II), and vaginal breech delivery (group III). RESULTS: There were 141 patients: 40 in group I, 66 in group II, and 35 in group III. There was no birth injury or neonatal death. Group II had one fetus with grade II intraventricular hemorrhage. There was no significant difference among the groups with regard to gestational age, birth weight, hyaline membrane disease, Apgar scores at 1 and 5 minutes, and cord blood gas indices, except venous pH in infants with birth weights <1500 g. CONCLUSIONS: Vaginal delivery of breech second-born twins, with gestational ages of at least 24 weeks, especially those with birth weights of > or =1500 g, appears to be a safe alternative to cesarean section.

Serial salivary estriol to detect an increased risk of preterm birth.

OBJECTIVE: To evaluate serial measurements of salivary estriol (E3) to detect increased risk of spontaneous preterm labor and preterm birth. METHODS: A masked, prospective, multicenter trial of 956 women with singleton pregnancies was completed at eight United States medical centers. Saliva was collected weekly, beginning at the 22nd week of gestation until birth, and tested for unconjugated E3 by enzyme-linked immunosorbent assay. Women were separated into high-risk and low-risk groups using the Creasy scoring system. RESULTS: A single, positive (at or above 2.1 ng/mL) salivary E3 test predicted an increased risk of spontaneous preterm labor and delivery in the total population (relative risk [RR] 4.0, P <.005), in the low-risk population (RR 4.0, P < or =.05), and in the high-risk population (RR 3.4, P =.05). Two consecutive positive tests significantly increased the RR in all study groups, with a dramatic improvement in test specificity and positive predictive value but only a modest decrease in sensitivity. In women who presented with symptomatic preterm labor, salivary E3 identified 61% of those who delivered within 2 weeks, using a threshold of 1.4 ng/mL. CONCLUSION: Elevated salivary E3 is associated with increased risk of preterm birth in asymptomatic women and symptomatic women who present for evaluation of preterm labor.

Does preeclampsia influence fetal lung maturity?

OBJECTIVE: This retrospective study compared the fetal lung maturity biochemical profile of patients having preeclampsia with that of patients having preterm labor. STUDY DESIGN: Amniotic fluid was obtained by transabdominal amniocentesis in 90 patients, 59 patients with preterm labor (PTL) and 31 patients with preeclampsia (PRE). Pregnancies with fetal growth restriction were excluded. Fetal lung maturity was assessed by lecithin/sphingomyelin ratio (L/S) and by a fluorescence polarimetry assay (FLM). Mean values of L/S ratios and FLM were compared between the PTL and the PRE groups, each within two gestational age subgroups (27-32.9 weeks gestation and 33-36 weeks gestation). Student t-test, Chi-square test Fisher's exact test were used for statistical analysis. A p value < 0.05 was considered significant. RESULTS: During the gestational age interval of 33-36 weeks, the mean L/S ratios were significantly lower in pregnancies complicated by PRE than in those complicated by PTL (1.99 +/- 0.26 and 2.4 +/- 0.57, respectively; p = 0.01). Similarly, during this gestational age interval, the FLM values were also lower in PRE than in PTL, although the difference did not reach statistical significance. CONCLUSION: During the gestational age between 33 and 36 weeks of gestation, the biochemical profile of preeclamptic patients without IUGR has a significant lower L/S ratio compared to that of preterm patients.

Tocolysis with advanced cervical dilatation.

OBJECTIVE: To assess the feasibility and potential benefit of delaying delivery in women with advanced preterm labor. METHODS: Two hundred fifty-seven gravidas with intact membranes and preterm labor at cervical dilatations of at least 3 cm were studied. Women were excluded if they had premature rupture of membranes, gestational age less than 24 or more than 35.9 weeks, complete cervical dilatation, severe hemorrhage, chorioamnionitis, and triplets or higher-order gestations. Management consisted of tocolysis with intravenous magnesium sulfate as the primary agent, antenatal steroids, antibiotics, and amniocentesis. The primary endpoint was delay to delivery interval. Statistical analyses by cervical dilatation were performed using the Pearson chi2 test and a nonparametric test of trend. RESULTS: Eighty-one percent of pregnancies were referrals in utero from outlying hospitals. Delivery was delayed 24 hours or longer in 74% and beyond 48 hours in 60% of cases. Among 229 women who delivered at our center, 21% remained undelivered after 1 week. Evaluating delay as a function of cervical dilatation, trend analysis found a highly significant inverse relationship (P < .001). Among women dilated 5 cm, 46% delivered beyond 48 hours. Among those dilated 6 cm or more, 19% delivered beyond 48 hours. Mild pulmonary edema developed in five percent, and all responded promptly to medical interventions. Chorioamnionitis developed in eight percent. CONCLUSION: Delaying delivery 24-48 hours to allow antenatal steroid use or other interventions is possible in women with advanced preterm labor.

Exercise during pregnancy: safe and beneficial for most.

Regular, moderate exercise does not significantly affect length of gestation or birth weight, and it may ease pregnancy and labor. Active pregnant women should maintain adequate hydration and nutrition, avoid hyperthermia, and take precautions if obstetric or medical complications are present. Supine exercise, contact sports, high-altitude exertion, and scuba diving should be avoided, and some women, including those who lift weights or do high-impact exercise, may need to modify their routines. Most women can begin or continue to exercise during pregnancy.

Third-trimester rudimentary horn pregnancy. A case report.

BACKGROUND: Müllerian ducts fuse in the midline to form the uterus at about 10 weeks' gestation. Rudimentary horn pregnancies are unusual occurrences. CASE: A 34-year-old woman presented at 24 weeks' gestation for prenatal care. Rudimentary horn pregnancy was diagnosed. Shortly afterwards the patient developed an acute abdomen, followed by emergency delivery. Though the risks of complications were high, none occurred. CONCLUSION: The incidence of rudimentary horn pregnancy is 1/100,000-150,000. Surgery is the treatment of choice. The prognosis is poor.

Physical activity, obesity, and diabetes in pregnancy.

Gestational diabetes mellitus (GDM) is the most common medical complication of pregnancy. Women with GDM are at elevated for numerous maternal health complications, and their infants are at elevated risk for death and morbidity. Management of GDM has traditionally been through diet and close monitoring of glucose levels, with initiation of insulin therapy when diet alone fails to maintain euglycemia. Recently, however, it has been suggested that alternative treatment modalities, such as exercise, may overcome a peripheral resistance to insulin, thus preventing GDM or controlling hyperglycemia in women with GDM. In this study, conducted from October 1995 to July 1996, the authors used a population-based birth registry to determine whether exercise has a preventive role in the development of GDM in women living in central New York State. They used contingency tables and chi-square statistics to examine bivariate differences among maternal and demographic variables and the occurrence of GDM. When stratified by prepregnancy body mass index category, exercise was associated with reduced rates of GDM only among women with a body mass index greater than 33 (odds ratio = 1.9, 95% confidence interval 1.2-3.1). The effect of exercise in obese women was further complicated by insurance status. When the data were stratified by insurance status, it appeared that women of higher socioeconomic status who were obese and did not exercise were at a significantly elevated risk of GDM compared with their counterparts of lower socioeconomic status. The results of this study suggest that for some women exercise may play a role in reducing the risk that they will develop GDM during pregnancy.

Prenatal HIV screening in pregnant women: a medical-legal review.

Identifying pregnant women's human immunodeficiency virus (HIV) infection status provides them with the opportunity to seek appropriate treatment and to take measures to prevent vertical and horizontal transmission. Prenatal screening program options include targeting at-risk women, testing on a voluntary basis, or mandating prenatal HIV screening. When examining these options, the number of cases identified, programmatic costs, long-term health care costs, and legal implications must all be considered. Research indicates that targeting at-risk women misses a significant percentage of seropositive women, although programmatic costs may be lower. It is difficult to ascertain the difference between voluntary and mandatory programs with respect to the number of cases identified and treated. As a result, long-term savings are difficult to calculate. Mandatory programs would have the greatest direct costs and place the greatest burden on the woman's constitutional rights. By making HIV counseling and testing a routine component of prenatal care, voluntary programs could achieve the benefits of prenatal HIV screening without violating the woman's civil liberties.

Association between pre-pregnancy obesity and the risk of cesarean delivery.

OBJECTIVE: To explore the relationship between pre-pregnancy obesity and the risk for cesarean delivery. METHODS: The population studied included 20,130 women with live births after 20 weeks' gestation in central New York state between June 1, 1994, and May 31, 1995. Women who were obese before pregnancy were compared with nonobese women with regard to mode of delivery. Obesity was defined as body mass index (BMI) greater than 29. Separate analyses were conducted on the entire sample and on a subset of women with singleton pregnancies and no prior cesarean deliveries, as an estimate of the risk of primary cesarean delivery in obese women. Statistical analyses included chi 2 test, crude odds ratio (OR) with 95% confidence interval (CI), and adjusted OR with 95% CI, using logistic regression to control for confounding variables. RESULTS: The adjusted OR was 1.64 (95% CI 1.46, 1.83) for obese women with singleton pregnancies and no prior cesarean deliveries to undergo cesarean delivery. The adjusted OR was 1.66 (95% CI 1.51, 1.82) for obese women in the entire sample to undergo cesarean delivery. In addition, increasing BMI was associated with increased risk for cesarean delivery. CONCLUSION: Compared with nonobese women, women who are obese before pregnancy are at increased risk for cesarean delivery. Preconceptional counseling regarding dietary and life-style modifications may alter this pattern.

Female alloimmunization with antibodies known to cause hemolytic disease.

OBJECTIVE: To determine the current frequency of red blood cell antigen alloimmunizations that are capable of causing hemolytic disease and would be suitable for prenatal DNA studies. METHODS: We reviewed blood-bank records at a single large tertiary center to identify patients with a positive antibody screen between January 1993 and June 1995. Data were analyzed based on age, gender, and specific blood-group alloimmunizations. The incidence of antibodies as published in the literature was reviewed and compared with our data. RESULTS: We identified 452 women who had a positive antibody screen. The frequencies of specific alloimmunization relevant to the development of fetal hemolytic disease were: anti-D, 18.4%; anti-E, 14%; anti-c, 5.8%; anti-C, 4.7%; Kell group, 22%; anti-MNS, 4.7%; anti-Fya (Duffy), 5.4%; and anti-Jka, 1.5%. Compared with other populations, in our group the frequency of antibodies to RhD decreased and Kell alloimmunization increased between 1967 and 1996. CONCLUSIONS: Despite the use of rhesus immune globulin, anti-D is still a common antibody identified in women presenting to a tertiary care center. The frequency of the Kell-group alloimmunization is higher among the central New York female population than in other populations. Rhesus and Kell antigen status can be determined by DNA studies. Research in prenatal determination of fetal antigen status should continue, as alloimmunization to these antigens is common.

A comparison of cross-sectional and longitudinal methods of assessing the influence of pregnancy on cardiac function during exercise.

To evaluate the influence of pregnancy on resting and exercise cardiac function, we studied 16 nonpregnant and 26 pregnant females in a two-phase study. During phase I, all pregnant subjects (P1) (mean gestational age = 29.5 +/- 7 weeks) were compared with 16 control (C) subjects. In phase II, 8 of the pregnant subjects (P2) (mean gestational age = 32.6 +/- 6 weeks) were evaluated again at 12.5 +/- 7 weeks postpartum (PP). Using Collier's CO2 rebreathing technique, exercise cardiac output (Q) was measured on a cycle ergometer during rest and at three submaximal work levels (25, 50, and 75 W), during the last minute of 5 to 7 minutes of steady-level power output. Metabolic parameters [ventilation (VE), heart rate (HR) and oxygen consumption (VO2)] were measured during the submaximal tests and throughout the progressive increase in work after the last measure of Q, until peak VO2 was achieved. The results from the phase I comparison indicated (as expected) higher resting heart rates [(90.0 +/- 3 P1; 81.8 +/- 3 bpm C), ventilation (9.5 +/- 0.3 P1; 7.5 +/- 0.5 L min-1 C), and resting oxygen consumption (0.263 +/- 0.07 P; 0.221 +/- 0.01 L min-1 C) associated with pregnancy, and these findings were similar when the pregnant subjects were compared with their postpartum values. Analysis of the various indices of cardiac function [Q, stroke volume (SV), and arteriovenous oxygen difference (A-VO2 diff)] resulted in statistically higher resting Q in pregnancy when compared with C and PP conditions. No resting differences were observed for SV or A-VO2 diff in either phase of the study. The results of the submaximal exercise tests indicated no significant differences in HR nor VO2 between P1 and C; however, P2 had significantly higher submaximal heart rates and oxygen consumption when compared with PP. Further, no significant differences were observed between P1 and C for Q, SV or A-VO2 diff, whereas P2 versus PP resulted in significantly lower SV and higher A-VO2 diff in the pregnant subjects. These findings suggest that pregnancy/control versus pregnancy/ postpartum studies yield statistically different results and that an effort needs to made by the research community to develop standardized methodologies to evaluate physiological processes in pregnancy.

A comparison of the ventilatory responses to exercise in pregnant, postpartum, and nonpregnant women.

To evaluate the influence of pregnancy on resting and exercise pulmonary function, we studied 16 nonpregnant and 26 pregnant females in a two-phase study. During phase I, all pregnant subjects (P1) (mean gestational age = 29.5 +/- 7 weeks [X +/- SD]) were compared with 16 control (C) subjects. In phase II, 8 of the pregnant subjects (P2) (mean gestational age = 32.6 +/- 6 weeks) were evaluated again at 12.5 +/- 7 weeks' postpartum (PP). Exercise respiratory function was measured during work on a cycle ergometer during rest and at three submaximal work levels (25, 50, and 75 W), during the last minute of 5 to 7 minutes of steady-level power output. Ventilatory parameters [ventilation (VE), ventilatory frequency (VF), tidal volume (TV), ventilatory equivalent for oxygen (VE/VO2) and ventilatory equivalent for carbon dioxide (VE/VCO2)] and metabolic parameters [oxygen consumption (VO2), oxygen pulse, carbon dioxide production (VCO2), respiratory exchange ratio (RER), and plasma lactate (HLA)] were measured during the submaximal tests and throughout the progressive increase in work after the 75 W work load, until peak VO2 was achieved. The results from the phase I comparison indicated (as expected) higher resting ventilation, tidal volume, oxygen consumption, carbon dioxide production, and respiratory exchange ratio associated with pregnancy, and these findings were similar when the pregnant subjects were compared with their postpartum values. Plasma lactate levels, although similar in the phase I comparison, were significantly higher during pregnancy when compared with postpartum values. No resting differences were observed for VF, O2 pulse, VE/VO, or VE/VCO2 in either phase of the study. The results of the submaximal exercise tests indicated higher submaximal levels of VE, VF, VE/VO2, VE/VCO2 in P1 versus C; however, P2 had significantly higher VE, TV, VO2, VE/VCO2, when compared with PP. The influence of pregnancy on VCO2 and RER differed by workload in both sets of comparisons. Furthermore, no significant differences were observed between P1 and C and P2 and PP for plasma lactate levels. These findings suggest that pregnancy/control versus pregnancy/postpartum studies yield different results in both ventilatory and metabolic comparisons. Consideration must be given to the type of study when discussing and applying the findings.

Prolonged exercise in pregnancy: glucose homeostasis, ventilatory and cardiovascular responses.

This study was designed to assess glucose homeostasis in pregnant women in their third trimester of gestation in response to exercise. Specifically, this study was designed to (1) compare the extend and rate at which blood glucose levels decrease in pregnant (22 to 33 weeks of gestation) versus that which occurs in nonpregnant women; and (2) determine the pattern of changes of the substrates (glucose, lactate, beta-hydroxybutyrate, and free fatty acids, and hormones (insulin), that contribute to the glucose homeostasis of pregnant (N = 10), and nonpregnant (N = 10) women in response to 1-hour prolonged moderate intensity exercise (at 55% of their VO2max). Each subject was tested for the determination of their maximal oxygen consumption (VO2max) and, based on their VO2max, they performed 60 minutes of prolonged moderate intensity exercise. Blood was collected before, during, and after the exercise bout. The results indicated that blood glucose levels of pregnant women decrease at a faster rate and to a significantly lower level post exercise (P < .05). Insulin levels of pregnant women also decreased to a significantly lower level post exercise, and lactate levels were maintained at a lower level 15 minutes after exercise. beta-hydroxybutyrate level was not different between the two groups, but demonstrated a different pattern of changes during exercise (P < .05). Furthermore, the results suggest that blood glucose levels of the late pregnant women decrease lower than those of nonpregnant women; also, there are differences in the rate and kinetics of blood glucose between pregnant and nonpregnant women. The results also indicate significant differences in the level of circulating substrates and hormones between pregnant and nonpregnant women in response to exercise.

Gestational diabetes and exercise: a survey.

Exercise has long been accepted as an adjunctive nonmedical intervention in the management of diabetes in nonpregnant subjects. It is universally accepted that pregnancy is a diabetogenic event which could develop into gestational diabetes mellitus (GDM) in up to 12% of pregnant women. GDM, a carbohydrate intolerance of variable severity with onset or first recognition during pregnancy, involves a relative resistance to insulin. Exercise becomes thus a logical intervention, only recently offered as an adjunctive therapy to pregnant diabetics. This article reviews our current understanding of the role of exercise in the management of GDM.

Body composition in pregnancy.

Concern over the influence of pregnancy-related alterations in hydration has prompted questions regarding the accuracy of using standard methods of determining body composition. We sought to investigate whether differences exist between body composition determined at 30 weeks and 39 weeks of gestation and postpartum, when measured by both bioelectrical impedance and hydrostatic weighing. This preliminary assessment of nine subjects suggests that the method used to calculate body composition during pregnancy can alter the influence of gestational age on body composition. The mechanisms underlying the differing results bear further investigation, as does the search for an accurate and reliable method for assessing body composition during pregnancy. Further research addressing these mechanisms is crucial to determining the relationship between changes in maternal fat and both maternal and fetal well-being.

Exercise: an alternative therapy for gestational diabetes.

Exercise can play a significant role in managing blood glucose levels in women who develop gestational diabetes and in women with type II diabetes who become pregnant. Because contracting muscles help stimulate glucose transport, exercise can help women control gestational diabetes without insulin. After constraints typical of pregnancy are taken into account such as soft-tissue laxity and fetal status exercise program can be tailored to the individual needs of patients. Although fit, active women may tolerate more strenuous exercise, relatively sedentary women may benefit most from non-weight-bearing exercises. Moderate workouts appear to be safe for most women who have gestational diabetes.

Salivary estriol as risk assessment for preterm labor: a prospective trial.

OBJECTIVE: Increased understanding of human parturition allows for novel approaches to (1) identification of women at increased risk for preterm birth and (2) development and controlled testing of etiology-based strategies to prevent preterm birth. STUDY DESIGN: Five hundred forty-two women were enrolled at five study sites in a prospective evaluation of salivary estriol in samples obtained weekly beginning at 22 weeks' gestation (Salest, Biex, Inc., Boulder, Colo.). Estriol concentrations were determined with a well-characterized enzyme-linked immunoassay. Women adjudged at either high risk or low risk for prematurity were evaluated through to delivery. RESULTS: A total of 267 women submitted serial samples that were analyzed; 241 women with singleton pregnancies submitted sufficient samples. Twenty-three women with singleton fetuses went into idiopathic preterm labor (without prior rupture of membranes) and were delivered preterm (mean 35 weeks' gestation); 182 were delivered at term (> or = 37 weeks' gestation). Mean (geometric) estriol concentrations were higher from 24 to 34 weeks in women with singleton pregnancies delivering preterm (p < 0.05). A surge in estriol concentrations occurred approximately 3 weeks before the onset of labor in both women delivering at term and those delivering preterm. This increase occurred approximately 4 weeks earlier in women delivered preterm versus term. Receiver-operator curve analyses showed that exceeding a 2.3 ng/ml saliva estriol level was associated with occurrence of preterm labor (71% sensitivity, 77% specificity, 23% false-positive rate). CONCLUSION: Detection of an early estriol surge or increased level (> or = 2.3 ng/ml) may be clinically helpful in identifying women at elevated risk for preterm labor and birth, allowing for evaluation of biologically based interventions in controlled trials.

A comparison of cardiopulmonary adaptations to exercise in pregnancy at sea level and altitude.

OBJECTIVE: The purpose of this study was to compare maternal cardiopulmonary and fetal responses of lowlander pregnant women in the third trimester to exercise at sea level and at an altitude of 6000 feet. STUDY DESIGN: Seven women at 33.86 +/- 1 weeks' gestation performed a symptom-limited maximal exercise test and a submaximal cardiac output exercise test at sea level at an altitude of 6000 feet. Cardiopulmonary and metabolic variables were measured and compared at sea level and altitude. RESULTS: Maximal oxygen consumption and work levels were limited by short-term altitude exposure. Ventilatory variables were not significantly influenced by altitude exposure. During submaximal exercise no alteration in exercise efficiency or response was seen for most of the variables when altitude and sea level data were compared. Both cardiac output and stroke volume were elevated at altitude at rest but not during exercise, suggesting a lower reserve for both variables at altitude. Level of plasma glucose, lactate, norepinephrine, and epinephrine were not significantly influenced by altitude exposure. Fetal heart rate responses did not differ between the sea level and altitude conditions. CONDITIONS: Lowlander pregnant women in the third trimester have some limitations to maximal aerobic capacity but not submaximal exercise on short-term altitude exposure. No ominous fetal responses have been observed during this study. The results suggest that pregnant women may engage in at least brief moderate exercise bouts at moderate altitude without adverse consequences.