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.

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.

Maternal catecholamines decrease during labor after lumbar epidural anesthesia

To determine whether epidural anesthesia during labor affects maternal circulating catecholamines, blood samples were obtained from 15 patients at the peak of and immediately after two consecutive painful contractions. A lumbar epidural local anesthetic without epinephrine was then administered. After the onset of analgesia, four blood samples were again drawn. All samples were analyzed by a radioenzymatic assay for epinephrine and norepinephrine concentrations. Before anesthesia, the mean (+/-SEM) plasma epinephrine level was 280 +/- 49 pg/ml, and the mean norepinephrine level was 866 +/- 122 pg/ml. After anesthesia, epinephrine levels decreased 56% (p less than 0.01). Although norepinephrine levels decreased approximately 19%, this reduction was not statistically significant. At the height of a contraction, catecholamine levels did not differ significantly from those occurring between contractions. Lumbar epidural anesthesia during labor reduces maternal epinephrine levels, probably by eliminating the psychological and physical stress associated with painful uterine contractions or by denervating the adrenal medulla. Whatever the mechanism, reducing pain and activity of the sympathetic nervous system should increase uterine blood flow.

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.

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.

Exercise in gestational diabetes. An optional therapeutic approach?

Forty-one patients with gestational diabetes requiring insulin were enrolled in a randomized study to investigate the efficacy of an exercise program in normalizing glucose tolerance. Seventeen of 21 patients completed the exercise program while maintaining normoglycemia and obviating insulin therapy. Maternal and neonatal complications did not differ between the study and control groups. The type of program described appears to be safe and can serve as a model for exercise prescription for pregnant diabetic women to attain improved glucose tolerance.

The mechanical properties of prematurely and non--prematurely ruptured membranes. Methods and preliminary results

The mechanical properties of the chorioamniotic membranes have been studied by several investigators over the past 100 years. No relationship between membrane strength, as measured by rupture tension, and premature or non-premature rupture of the membranes has been demonstrable. In the present study, several measures of the mechanical properties of the chorioamniotic membranes were examined. These included thickness, rupture tension, work to rupture, strain to rupture, and moduli of elasticity (Young). Prematurely and non-prematurely ruptured membranes differed with respect to thickness near the rupture site and Young's modulus near the placenta. Differences between the groups for the other parameters were not significant. This study suggests that there may be inherent differences between membranes which rupture prematurely and those which do not.

Pulmonary responses to exercise in pregnancy

The pulmonary responses of 88 pregnant women were compared to those of 39 nonpregnant control subjects during different exercise intensities. At rest the pregnant women had higher tidal volumes, oxygen consumption, carbon dioxide production, and respiratory exchange ratio. With increased work loads the pregnant volunteers have consistently lagged behind the nonpregnant control subjects for every parameter, which indicates a decrease in pulmonary reserve and inability to exercise anaerobically.

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.

C-reactive protein as a predictor for chorioamnionitis in cases of premature rupture of the membranes

We evaluated C-reactive protein for its ability to predict the occurrence of clinical chorioamnionitis in 51 patients with spontaneous premature rupture of the membranes at less than or equal to 34 weeks of gestational age. All the patients had determinations of C-reactive protein on admission, and then 25 patients were tested daily. Of the total 51 patients, 14 developed clinical signs compatible with a diagnosis of chorioamnionitis. An analysis was conducted to compare the use of C-reactive protein to that of white blood cell count in predicting febrile disease. Our study indicates that C-reactive protein is an accurate and early marker for predicting clinical chorioamnionitis. White blood cell and differential counts are less accurate in such prediction, especially after steroid treatment.

Fetal heart rate responses to maternal exercise

The fetal heart rate responses to mild, moderate, and strenuous maternal exercise were studied in 45 healthy subjects. In the majority of cases, the fetal heart rate increased during and after maternal exercise. Fetal bradycardia was recorded in five fetuses; this appears to be a sporadic event. There was no correlation between the individual fetal heart responses, gestational age, exercise intensity, and maternal circulating catecholamines.

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.

C-reactive protein in pregnancy and in the postpartum period

Serum C-reactive protein levels were measured by means of the nephelometric immunoassay technique in 215 pregnant women at various gestational ages. The results indicate a positive correlation of serum C-reactive protein levels with gestational age. In addition, we studied serum C-reactive protein concentrations in 37 pregnant women in labor and during the postpartum period. Delivery was accomplished by either the vaginal or abdominal route and was associated with significant C-reactive protein production.

Fetal bradycardia induced by maternal exercise

Fetal bradycardia that occurred during maternal exercise (a symptom-limited VO2 max treadmill test) in the fetuses of three healthy pregnant women is described. The mechanism of this bradycardia is believed to be mediated by catecholamines. The fetal bradycardia seems to be transitory and appears to be compensated for by an increase in fetal heart rate after the cessation of exercise.

Therapeutic exercise for insulin-requiring gestational diabetics: effects on the fetus--results of a randomized prospective longitudinal study

Regular physical activity is an established therapeutic adjunct in diabetes, but has not been offered to pregnant diabetics in the past; for sports might induce significant cardiovascular and hormonal changes that are able to reduce blood flow to the uterus and thus limit oxygen transfer to the fetus. Studying the impact of a medically supervised exercise program on gestational diabetes mellitus [GDM) in a randomised prospective longitudinal study, this paper aims to assess the effects of maternal moderate and strenuous exercise on the fetus. By evaluating shortterm fetal responses as reflected in heart rate patterns (FHR) and longterm-pregnancy complications and neonatal outcome, our results suggest that--in absence of ominous FHR changes or significant changes in uterine activity following the exercise sessions or increased diabetes-related peri- and neonatal morbidity--regular physical activity seems to be a safe therapeutic option for the fetus of GDM mothers.

Recent advances in understanding maternal and fetal responses to exercise

In the past decade, physical health fitness has become increasingly more important in the lives of women of child-bearing age. Many have made regular, and sometimes vigorous commitments to exercise programs. In 1985, the American College of Obstetricians and Gynecologists (ACOG) developed a set of guidelines for women who plan to exercise during pregnancy. Recommendations were based on available, but somewhat limited, scientific data and common sense. Since that time, researchers have learned a significant amount of new information about how a pregnant woman and her fetus respond to aerobic activity. The objective of this communication is to review recent investigations in this area. Specific topics include a) maternal responses to exercise, b) fetal responses to maternal exercise, c) animal research models, and d) pregnancy and physical conditioning. Our objectives are to present information that will a) stimulate new and innovative research designs for exercise and pregnancy studies, and b) add significantly to our knowledge and ability to develop safe and effective exercise programs for women who wish to remain physically active throughout a normal-term pregnancy.

A randomized multicenter trial assessing a home uterine activity monitoring device used in the absence of daily nursing contact

OBJECTIVE

To evaluate the effectiveness of home uterine activity monitoring in the early detection of preterm labor among women with a history of preterm delivery.

STUDY DESIGN

Two hundred eighteen women from four centers were prospectively randomized to routine high-risk prenatal care alone (not monitored) or to the same prenatal care with twice-daily home uterine activity monitoring without daily nursing support (monitored). All women had a history of preterm delivery. The primary study end point was cervical status as measured by cervical dilatation at the time of diagnosis of preterm labor.

RESULTS

The two study group populations at entry into the study were similar in medical and demographic characteristics. Of 187 women completing the trial, 21 (24.4%) of the women in the monitored group (n = 86) and 22 (21.8%) of the women in the unmonitored (control) group (n = 101) experienced preterm labor (not significant). Mean cervical dilatation at the time of diagnosis of preterm labor was 1.7 cm in the monitored group and 2.8 cm in the unmonitored group (p = 0.004). A total of 52.4% of the women in the monitored group had a cervical dilatation of < 2 cm when preterm labor was detected, compared with 18.2% of the women in the unmonitored group (p = 0.019). The median duration of gestation after diagnosis of preterm labor was 21.0 days for the monitored group and 3.0 days for the unmonitored group (p = 0.016).

CONCLUSION

The diagnosis of preterm labor for women using home uterine activity monitoring without daily nursing contact was detected with less cervical dilatation than found in those women not monitored. This earlier detection of preterm labor demonstrates the utility and effectiveness of home uterine activity monitoring devices and may lead to improved neonatal outcomes.

Sympathoadrenal activity, maternal, fetal, and neonatal responses after epidural anesthesia in the preeclamptic patient

This study confirms that preeclamptic patients have higher plasma levels of catecholamine than those of normal patients. It also demonstrates that epidural analgesia when administered to the preeclamptic patient during labor is followed by a significant reduction in the plasma levels of catecholamines without any adverse effects on maternal blood pressure, uterine activity, fetal heart rate, or the neonate.

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.

Hybrid Ni@ZnO@ZnS-Microalgae for Circular Economy: A Smart Route to the Efficient Integration of Solar Photocatalytic Water Decontamination and Bioethanol Production

Water remediation and development of carbon-neutral fuels are a priority for the evermore industrialized society. The answer to these challenges should be simple, sustainable, and inexpensive. Thus, biomimetic-inspired circular and holistic processes combing water remediation and biofuel production can be an appealing concept to deal with these global issues. A simple circular approach using helical Spirulina platensis microalgae as biotemplates to synthesize Ni@ZnO@ZnS photocatalysts for efficient solar water decontamination and bioethanol production during the recycling process is presented. Under solar irradiation, the Ni@ZnO@ZnS-Spirulina photocatalyst exhibits enhanced activity (mineralization efficiency >99%) with minimal photocorrosion and excellent reusability. At the end of its effective lifetime for water remediation, the microalgae skeleton (mainly glycogen and glucose) of the photocatalyst is recycled to directly produce bioethanol by simultaneous saccharification and fermentation process. An outstanding ethanol yield of 0.4 L kg-1, which is similar to the highest yield obtained from oxygenic photosynthetic microorganisms, is obtained. Thus, the entire process allows effective solar photocatalytic water remediation and bioethanol production at room temperature using simple and easily scalable procedures that simultaneously fixes carbon dioxide, thereby constituting a zero-carbon-emission circular process.

An in vitro model for the study of enzymatically mediated biomechanical changes in the chorioamniotic membranes

The effects of different incubation media on the biomechanical properties of nine chorioamniotic membranes were studied. Significant alterations in strain/rupture, work/rupture, and rupture/tension values have been demonstrated after a 24 hour incubation period in pseudoamniotic fluid (PAF). These changes can be arrested if enzyme inhibitors are added to the incubation media. This study suggests that biomechanical alterations in the chorioamniotic membranes may be biomechanical, namely, enzymatically mediated.

Exercise prescription in pregnancy: weight-bearing versus non-weight-bearing exercise

Bicycle ergometry (non-weight-bearing exercise) and treadmill (weight-bearing exercise) were compared to assess physiologic responses to similar work loads. A total of 22 subjects at 29.3 +/- 1.6 (+/- SEM) weeks' gestation who performed non-weight-bearing exercise were compared with 15 similarly fit subjects at 26.1 +/- 2.3 weeks' gestation who performed weight-bearing exercise at three submaximal levels. Measurements by indirect calorimetry indicate preferential carbohydrate use during non-weight-bearing exercise at submaximal levels.

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.

Hormonal responses to exercise in diabetic and nondiabetic pregnant patients

The hormonal responses to low-level exercise in pregnancy have been studied in 13 insulin-requiring diabetic patients and 42 control subjects. We found no significant changes in plasma glucose, epinephrine, glucagon, or FFA with this level of exercise in the study group and control subjects; but plasma norepinephrine showed a significant increase with exercise. This type of exercise appears to be safe and could serve as a model for exercise prescription for attaining improved glucose tolerance in pregnant diabetic women.