Vascular dimorphism ensured by regulated proteoglycan dynamics favors rapid umbilical artery closure at birth

The umbilical artery lumen closes rapidly at birth, preventing neonatal blood loss, whereas the umbilical vein remains patent longer. Here, analysis of umbilical cords from humans and other mammals identified differential arterial-venous proteoglycan dynamics as a determinant of these contrasting vascular responses. The umbilical artery, but not the vein, has an inner layer enriched in the hydrated proteoglycan aggrecan, external to which lie contraction-primed smooth muscle cells (SMC). At birth, SMC contraction drives inner layer buckling and centripetal displacement to occlude the arterial lumen, a mechanism revealed by biomechanical observations and confirmed by computational analyses. This vascular dimorphism arises from spatially regulated proteoglycan expression and breakdown. Mice lacking aggrecan or the metalloprotease ADAMTS1, which degrades proteoglycans, demonstrate their opposing roles in umbilical vascular dimorphism, including effects on SMC differentiation. Umbilical vessel dimorphism is conserved in mammals, suggesting that differential proteoglycan dynamics and inner layer buckling were positively selected during evolution.

Development of an outpatient clinic to provide pertussis vaccinations to maternity patients and family members

PURPOSE

The implementation of a hospital-based outpatient pertussis prevention program targeting maternity patients and family members is described.

SUMMARY

Faced with a rising incidence of pertussis statewide, a large Ohio hospital formed a multidisciplinary team to ensure hospital compliance with current guidelines calling for administration of the tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine to all maternity patients as well as previously unvaccinated family members and likely neonatal caregivers (i.e., "cocooning"). The team had regularly scheduled meetings to identify and address fiscal, logistic, and practice-related challenges throughout the implementation process. Key challenges included (1) determining the availability of insurance reimbursement for Tdap vaccination services, (2) cultivating support for the vaccination initiative among obstetrics and maternal-fetal medicine specialists, (3) coordinating development and dissemination of educational information to patients and their families at specified points of contact, and (4) establishing an efficient registration process for family members. The outpatient vaccination clinic was located adjacent to the hospital's maternity center in order to provide convenient access. Despite limited clinic hours (three hours daily on weekdays only) and ongoing reimbursement and funding challenges, the program has improved Tdap vaccination rates in the target population and is considered a successful demonstration of the cocooning concept.

CONCLUSION

Implementation of an outpatient clinic for neonatal pertussis prevention was well accepted by family members of newborns, and Tdap vaccinations were administered to 329 family members during the first 11 months of clinic operations.

Management of group B Streptococcus in pregnant women with penicillin allergy

OBJECTIVE

To determine whether group B Streptococcus (GBS)-colonized pregnant women who report a history of penicillin allergy can safely undergo diagnostic evaluation to rule out or confirm the potential for an IgE-mediated (allergic) reaction to penicillin.

STUDY DESIGN

Over 18 months, all pregnant women with GBS-positive vaginal/rectal cultures and a history of penicillin allergy were referred to the Department of Allergy and Immunology for a history and possible skin testing. Patients who had experienced anaphylaxis were advised to continue avoiding penicillin and were not skin tested. Women without such a history underwent immediate hypersensitivity (percutaneous and intradermal) testing using 2 penicillin reagents with controls. If skin testing was negative, intrapartum antimicrobial prophylaxis with intravenous penicillin was administered.

RESULTS

Of 28 patients with both GBS colonization and "penicillin allergy," 25 (89%) had negative skin testing to penicillin and received intrapartum penicillin for GBS prophylaxis without adverse reactions. Skin testing was positive in 2 patients, and intrapartum penicillin was not administered. Penicillin skin testing was not performed on 1 patient due to a history of anaphylaxis from penicillin.

CONCLUSION

These results indicate that most pregnant women reporting penicillin allergy undergo negative skin tests and are able to safely receive intrapartum penicillin GBS prophylaxis.

Fetal erythrocyte phospholipid polyunsaturated fatty acids are altered in pregnancy complicated with gestational diabetes mellitus

Insulin resistance and altered maternal metabolism in gestational diabetes mellitus (GDM) may impair fetal arachidonic acid (AA) and docosahexaenoic acid (DHA) status. The objectives were to test the hypothesis that fetal polyunsaturated fatty acids would be altered with GDM and identify factors related to fetal phospholipid (PL) AA and DHA. Maternal and cord vein erythrocyte PL fatty acids were determined in GDM (n = 13) and healthy pregnant women (controls, n = 12). Cord vein erythrocyte PL AA and DHA concentrations were significantly lower in GDM vs. controls. Maternal blood hemoglobin A1C was inversely correlated to fetal erythrocyte PL DHA and AA in controls and GDM (n = 25). Pregravid body mass index was negatively associated with fetal PL DHA. The data support the hypothesis that there is impairment in fetal accretion of DHA and AA in GDM.

Effectiveness of a writing improvement intervention program on the readability of the research informed consent document

BACKGROUND

Problems with the comprehensibility of human research informed consent have been documented since the 1970s, and efforts aimed at rewriting consents have not been successful in consistently producing more readable consents. This study employed researched principles of reading comprehension research to create writing intervention program designed to help the research writer produce more comprehensible informed consent documents. The purpose of this study was to determine if this intervention program was effective.

METHOD

The key component of the writing improvement intervention packet was a newly formatted consent form that contained annotated instructions for researchers on how to write each section for optimum comprehension. The resulting consent forms were evaluated using a Readability and Processability Form (RPF). The RPF is based on reading research and includes the Fry Scale, which yields an approximate grade reading level. The RPF assigned points to each of the 20 areas of comprehension analysis according to strict scoring criteria, and target scores were established by the authors in consultation with the hospital institutional review board.

RESULTS

We evaluated 66 post-intervention informed consents. The mean readability and processability score was 62, resulting in the RPF classification of "good." The established readability and processability target range was good to excellent or 61-100 points; 66% of the forms scored in this range. In our 1995 pre-intervention study, the corresponding score was 12%. The target range for grade reading level was 8th grade: 53% scored in that range as compared with 4% in 1995. A question-by-question analysis of each of the 20 checklist items on the RPF identified important aspects of the consent writing that improved and others that were still weak and needed improvement.

CONCLUSIONS

The Hartford Hospital writing improvement intervention program was associated with the production of more comprehensible informed consent documents. Using the intervention materials, investigators from a variety of departments could function independently to produce readable consent forms. This program may help others who wish to assist their research departments in creating consents that are written for optimal reading comprehension.

The role of the maternal-fetal medicine specialist

The maternal-fetal medicine specialist is trained to manage high-risk pregnancies and obstetric complications. This paper describes the role of the maternal-fetal medicine specialist on the obstetric health care team and conditions in which he or she may enhance the outcome of pregnancy.

Maternal plasma phospholipid polyunsaturated fatty acids in pregnancy with and without gestational diabetes mellitus: relations with maternal factors

BACKGROUND

The fatty acids arachidonic acid (AA; 20:4n-6) and docosahexaenoic acid (DHA; 22:6n-3) are essential for fetal growth and development, but their metabolism may be altered in insulin resistance.

OBJECTIVES

The objectives were to determine maternal plasma phospholipid polyunsaturated fatty acid concentrations in pregnant women receiving dietary therapy for gestational diabetes mellitus (GDM) and to identify maternal factors associated with plasma phospholipid AA and DHA concentrations in the third trimester.

DESIGN

Fasting plasma phospholipid fatty acids were determined in women with GDM (n = 15) receiving dietary therapy only and in healthy, pregnant women without GDM (control group, n = 15) at 27-30, 33-35, and 36-39 wk gestation.

RESULTS

Maternal plasma phospholipid (as % by wt of total fatty acids and mg/L) linoleic acid (18:2n-6), AA, and 22:5n-6 concentrations did not differ significantly between women with GDM and control subjects. The other n-6 long-chain polyunsaturated fatty acids (% by wt) were lower in GDM subjects than in control subjects. Plasma phospholipid (expressed as % by wt and mg/L) linolenic acid (18:3n-3) and summed precursors of DHA were lower and DHA (% by wt and mg/L), adjusted for dietary DHA intake, was 13% higher in GDM subjects than in control subjects. Maternal blood hemoglobin A1C was inversely related to plasma phospholipid AA (% by wt) (r = -0.56, P = 0.03) in control subjects and positively associated with plasma phospholipid AA (% by wt) in women with GDM (r = 0.76, P = 0.001). Pregravid body mass index was negatively associated with plasma phospholipid DHA (% by wt) in control subjects (r = -0.55, P = 0.04) and in women with GDM with a body mass index (in kg/m2) <30 (r = -0.76, P = 0.007).

CONCLUSIONS

This is the first report documenting alterations in maternal plasma phospholipid PUFAs in pregnant women receiving dietary therapy for GDM. In pregnant woman, both with and without GDM, maternal glycemic control and pregravid BMI appear to be significant predictors of plasma phospholipid AA and DHA, respectively, during the third trimester. Additionally, dietary DHA significantly affects phospholipid DHA concentrations.

Chaperone use by obstetrician/gynecologists

OBJECTIVE

To describe current practices of chaperone use during pelvic examinations among obstetrician/gynecologists affiliated with a large tertiary care teaching hospital.

STUDY DESIGN

Questionnaires were distributed at department of obstetrics and gynecology grand rounds to all practicing attending physicians to obtain physician demographic data, including age, years in practice, practice type (solo or group) and whether chaperones were currently used when performing pelvic examinations at the first obstetric or gynecologic office visit. Physicians were also asked whether they were taught to use chaperones for pelvic examinations during medical school or residency.

RESULTS

Of the 59 attending physicians, 100% responded to the questionnaire. As compared to female physicians, male physicians used chaperones more at the first obstetric examination (76.9% vs. 27.8%, P < .002), at gynecologic office visits (70.0% vs. 22.2%, P < .002) and for breast examinations (51.2% vs. 11.1%, P < .01). Physicians greater than 40 years old, in practice longer than 10 years and taught as medical students or residents to use chaperones were statistically more likely to use chaperones. No attendings, male or female, reported losing a patient to another provider or being sued or threatened with legal action because of not using a chaperone.

CONCLUSION

Chaperones were used more frequently during pelvic examinations by male physicians, age greater than 40, solo practice, and physicians in practice longer than 10 years. Education affected current practices as specific medical student or residency training influenced the use of chaperones in private practice.

Maternal and cord plasma lipid and lipoprotein concentrations in women with and without gestational diabetes mellitus. Predictors of birth weight?

OBJECTIVE

To describe lipid and lipoprotein perturbations in gestational diabetes mellitus (GDM) and to examine the potential consequences--e.g, increased birth weight and increased placental lipid transfer.

STUDY DESIGN

Maternal and cord free fatty acids (FFAs) and total, very low density lipoprotein (VLDL), low density lipoprotein (LDL), high density lipoprotein (HDL) (and maternal HDL2 and HDL3), triglyceride (TG), and cholesterol and dietary intake were determined for women with diet-treated GDM and for healthy pregnant women with normal glucose tolerance.

RESULTS

Women with GDM had higher hemoglobin A1c than controls, while body weight gain was significantly lower for women with GDM as compared to controls. Plasma and lipoprotein TG concentrations were greater for women with GDM, and although plasma FFAs were higher in women with GDM versus controls, the difference was not significant. No differences were observed between groups with respect to maternal plasma or lipoprotein cholesterol. Cord plasma and lipoprotein lipids were similar between groups; with the exception of VLDL + LDL TG, which was lower in women with GDM. In controls, there were significant correlations between maternal plasma TG and cord FFAs; maternal HDL2 cholesterol and cord plasma cholesterol; and maternal plasma TG, maternal HDL2 cholesterol, cord FFAs, and infant birth weight. In GDM, maternal plasma cholesterol and cord VLDL + LDL cholesterol correlated. There were no significant correlations between maternal or cord lipids and infant birth weight in women with GDM.

CONCLUSION

Hypertriglyceridemia, rather than hypercholesterolemia, is a feature of GDM. However, elevations in maternal plasma and lipoprotein TGs in women with GDM were not related to fetal lipid concentrations or infant birth weight.

Umbilical cord prolapse. Is the time from diagnosis to delivery critical?

OBJECTIVE

To review the peripartum clinical course of patients whose pregnancies are complicated by umbilical cord prolapse at a large teaching hospital and to evaluate the time from diagnosis to delivery and its impact on neonatal outcome.

STUDY DESIGN

The computerized perinatal database at Hartford Hospital was used to identify all cases of umbilical cord prolapse from 1988 to 1994. Each maternal and neonatal chart was reviewed, and the following variables were evaluated: gestational age, fetal presentation, status of membranes, time from diagnosis to delivery, mode of delivery, type of anesthesia and neonatal outcome.

RESULTS

A total of 65 cases of umbilical cord prolapse were identified from 26,545 deliveries. There were 48 cases of frank cord prolapse and 17 of occult prolapse. Cord prolapse occurred with artificial rupture of membranes in 51% of cases and in 74% of patients at term. There were 59 cesarean births and 6 vaginal deliveries (5 in the occult prolapse group). The mean time from diagnosis to delivery was 20 minutes (range, 2-77). None of the neonates with an occult cord prolapse had a five-minute Apgar score < 7, while 9 (19%) of the neonates with frank prolapse had a five-minute Apgar score < 7. In the frank prolapse group, there were five cases of neonatal asphyxia, all at a gestational age of > or = 36 weeks, and all were delivered by cesarean section. The mean delivery time for these affected neonates was 11 minutes (range, 5-16).

CONCLUSION

Our review indicated that umbilical cord prolapse continues to be associated with poor perinatal outcomes in some cases despite emergency delivery in a modern, high-risk obstetric unit. The asphyxiated neonate had a shorter-than-average time from diagnosis to delivery, suggesting that the time from diagnosis to delivery may not be the only critical determinant of neonatal outcome, particularly with frank cord prolapse. Occult cord prolapse was associated with less perinatal morbidity when compared to frank prolapse.

Elevated lipoprotein lipids and gestational hormones in women with diet-treated gestational diabetes mellitus compared to healthy pregnant controls

The objective of this study was to describe plasma and lipoprotein perturbations in gestational diabetes mellitus (GDM) compared to controls, and determine if alterations in lipids are related to gestational hormones and/or glucose control. Maternal HbA1c, free fatty acids (FFA), beta-estradiol, progesterone, prolactin, and plasma, very-low-density lipoprotein (VLDL), low-density lipoprotein (LDL), high-density lipoprotein (HDL), HDL2 and HDL3 triglyceride (TG), cholesterol, and dietary intake were determined for women with diet-treated GDM and controls in a longitudinal design. Subjects (N = 25/group) were matched for age, race, and body-mass index (BMI). Women with GDM had significantly higher HbA1c than controls, although both groups were within the normal range (4%-6%). However, body weight gain was less for women with GDM. There was a trend for higher plasma FFAs at 37-38 weeks in GDM versus controls. Plasma and lipoprotein TG among the groups increased over the third trimester, and mean concentrations were greater for women with GDM. In GDM versus controls, VLDL and HDL3 TGs were higher at all times, HDL and HDL2 TGs at 33-34 and 37-38 weeks, and LDL TGs at 37-38 weeks. In VLDL, core lipids (TG + cholesterol) increased over gestation and were greater in GDM. In HDL, the TG/cholesterol ratio was greater in GDM. In GDM versus controls, plasma progesterone and prolactin were higher at all times; beta-estradiol was elevated at 37-38 weeks. HbA1c, progesterone, and prolactin correlated with all lipoprotein TG fractions. Exaggerated hypertriglyceridemia, particularly in the VLDL and HDL fractions, is a feature of GDM. The increase in VLDL TG is likely due to an increase in VLDL synthesis, whereas particle enrichment in TG is a plausible explanation for changes in HDL TG. Slight perturbations in glucose control and gestational hormones in diet-treated GDM may contribute to the observed increase in plasma and lipoprotein TG.

External cephalic version of twin A

BACKGROUND

When a first twin presents as a breech, cesarean delivery is generally recommended. Vaginal delivery of the first twin as a breech has also been described. However, the option of external cephalic version of the first twin, followed by vaginal delivery, is rarely considered.

CASES

We report two cases in which twin A presented as a breech, one at 36 and one at 38 weeks' gestation. In each case, external cephalic version of the first twin was successful, with subsequent vaginal delivery of both twins.

CONCLUSION

External cephalic version of a malpresenting first twin is a management option that can result in successful vaginal delivery.

Intrapartum chemoprophylaxis for group B streptococcus infection to prevent neonatal disease: who should be treated?

The purpose of this study was to examine the maternal risk factors associated with early onset Group B streptococcus (GBS) sepsis and determine the potential impact of intrapartum chemoprophylaxis using these risk factors. Using a computerized perinatal database, 26,525 deliveries over a five-year period (1989 to 1994) were identified. Neonates with GBS-positive cultures were identified and the neonatal and maternal chart of each case was reviewed. Twenty-six neonates (1 of 1000) had GBS sepsis documented by blood or cerebrospinal fluid culture. Maternal risk factor(s) were identified in 13 (50%) cases: preterm labor (5), preterm premature rupture of the membranes (5), prolonged rupture of membranes (6), sibling affected by symptomatic GBS infection (2), or maternal fever during labor (5). There were four mothers whose neonates had GBS sepsis in spite of intrapartum antibiotics. Intrapartum chemoprophylaxis for GBS based on risk factors alone will identify only half of the neonates who develop disease. Extension of intrapartum chemoprophylaxis to patients with risk factors appears to be necessary to prevent early onset disease in the other half. Since 85.7% of our total obstetrical population has no risk factors, this policy would require treating 1749 women to prevent one case of GBS sepsis. Chemoprophylaxis could be more appropriately targeted if mothers colonized with GBS could be identified in early labor.

Informed consent for research: a study to evaluate readability and processability to effect change

BACKGROUND

Ninety million Americans are reported to have low literacy skills, and the problems associated with illiteracy permeate all areas of our society, including medical research. The purpose of this study was to determine the readability and comprehensibility of human research informed consent forms using established reading comprehension processes. Further, if comprehension problems were present in the forms, the study sought to identify the exact nature of these difficulties and identify specific areas where the forms could be rewritten to increase readability and understanding.

METHODS

All human research informed consents approved by Hartford Hospital in 1993 were evaluated by a Readability and Processability Form (RPF) based on reading research, including the Fry Scale which yields an approximate grade reading level. The RPF assigned points to each of the 20 areas of analysis according to strict scoring criteria, and target scores were established by the authors in consultation with the hospital.

RESULTS

Seventy-six informed consent forms were evaluated, and neither the Fry score or the RPF score was in the target range. Ninety-six percent of the forms were found to have readability levels higher than the target level (8th grade). The mean readability and processability score was 46, resulting in the classification, Minimally Adequate/Needs Improvement. (The target range was Good, 61-100.) A question by question analysis of each of the 20 checklist items on the RPF identified important aspects of text writing style that were scored as Unacceptable or Poor.

CONCLUSIONS

The descriptive data indicates that there were problems with the readability of the informed consent documents studied. The prescriptive portion of this study provides researchers with information on specific areas where their forms need to be studied and rewritten. The comprehension problems found in this study may alert others to similar problems and may provide the basis for other institutional review boards (IRBs) to study their consent forms in order to ensure that the interests of both the patient and the researcher are protected and that the obtained consent is truly informed.

Enhanced antenatal detection of group B streptococcus colonization

OBJECTIVE

To improve culture methods for the detection of group B streptococcus colonization.

METHODS

This study prospectively compared the standard culture medium, a blood agar plate, to a selective culture medium, Todd Hewitt broth with antibiotics, and compared vaginal culture with rectal culture at the first prenatal exam.

RESULTS

Of the 383 vaginal swabs received for evaluation of the two culture media, 78 (20.4%) were positive for group B streptococcus. The detection rates of the blood agar plate method and the Todd Hewitt broth with antibiotics were 64.1 and 97.4%, respectively. Using the Todd Hewitt broth with antibiotics, an additional 94 patients were cultured vaginally and rectally. Twenty-nine (30.9%) had positive cultures. The rate of detection was 58.6% for the vaginal culture, 89.7% for the rectal culture, and 100% for both culture sites combined.

CONCLUSION

These data indicate that culture detection of group B streptococcus can be improved by using both a selective broth medium and a dual vaginal and rectal culture.

Preterm premature rupture of membranes: experience with latent periods in excess of seven days

The purpose of this study was to review the maternal and neonatal outcomes of patients with preterm premature rupture of membranes (PPROM) with a latency period greater than 7 days. Using the perinatal database, there were 11,007 deliveries in a 25-month period, in which 81 patients (0.7%) with singleton pregnancies were admitted with documented PPROM between 20 and 30 weeks' gestation. Twenty-one patients (26%) remained undelivered after 1 week, and 19 of these patients were discharged to outpatient care. Twelve patients (57%) delivered at term and nine patients (43%) delivered prematurely. In the preterm group all reported increased leaking prior to delivery and all neonates had 5-minute Apgar scores higher than 7. Length of stay in the neonatal intensive care unit for all the preterm neonates ranged from 12 to 117 days. The majority of patients with PPROM will deliver within 1 week, but there is a subset of patients with PPROM (one of every seven), characterized by the absence of labor or infection, who may be managed as outpatients and delivered at term.

Quality assurance: measuring its effect on a busy obstetric service

OBJECTIVE

To evaluate the effect of establishing a new quality assurance program in obstetrics at a large teaching hospital.

METHODS

Seven obstetric clinical indicators were selected. After the computerized data base identified the patients as outliers from these indicators, the medical record of each patient was reviewed. Each case was presented to the nine-member committee, which made recommendations or actions for changes or improvement in patient care. The number of patients coming to review and the number of clinical indicators from the year before the program were compared to the results of the second year of the program.

RESULTS

The new program significantly reduced the number of patient records reviewed and the clinical indicators. Of the clinical indicators, prolonged hospitalization after both vaginal and cesarean births was decreased. Recommendations to the department included the need for better chart documentation, specific educational presentations as grand rounds, and a protocol for antibiotic use for postpartum endomyometritis.

CONCLUSION

A quality assurance program in obstetrics may decrease the number of clinical indicators after only 1 year. This decreasing trend and better documentation may be considered as measures of improvement in obstetric care.

A randomized comparison of 15- and 40-minute dosing protocols for labor augmentation and induction

OBJECTIVE

To compare two low-dose oxytocin protocols in terms of fetal distress, uterine hyperstimulation, cesarean delivery rate, maximum dose of oxytocin, and length of labor.

METHODS

We randomized 865 patients into 15-minute (incremental dose 1 mU/minute until 5 mU/minute, then 1 or 2 mU/minute) or 40-minute (incremental dose 1.5 mU/minute until 7 mU/minute, then 1.5 or 3.0 mU/minute) low-dose protocols. Before oxytocin use, all subjects were stratified according to parity and purpose of oxytocin, ie, for induction or augmentation of labor.

RESULTS

The 40-minute dosing protocol had a significantly lower maximum dose of oxytocin (augmentation, 6.5 versus 8.2 mU/minute, P < .001; induction, 11.5 versus 14.5 mU/minute, P < .001), a lower incidence of uterine hyperstimulation (augmentation, 18.8 versus 31.8%, P < .001; induction, 19.1 versus 33.0%, P < .002), and less fetal distress (augmentation, 15.5 versus 26.1%, P < .005). No significant differences were found in the cesarean rate or length of labor.

CONCLUSION

A dosing interval of 40 minutes led to lower incidences of uterine hyperstimulation and fetal distress, and decreased the maximum dose of oxytocin, without affecting the length of labor or the cesarean rate.

Glucose, insulin, gastric inhibitory polypeptide, and pancreatic polypeptide responses to polycose during pregnancy

Polycose, a glucose polymer produced by controlled acid enzyme hydrolysis of starch, has been proposed as an effective substitute for glucose solution in antepartum screening for glucose intolerance. The purposes of this study were to examine the glucose and hormonal responses to 50 g of glucose polymer (polycose) solution in pregnant and nonpregnant women and to compare these with the standard 50-g oral glucose challenge test. In addition, the subject's acceptance of the glucose polymer solution was evaluated. Subjects were examined after an overnight fast following a 3-day dietary preparation. There was no difference in glucose or insulin responses to glucose or polycose in either pregnant or nonpregnant women. In contrast, the gastric inhibitory polypeptide response to polycose was significantly higher than to glucose. No differences were observed in plasma pancreatic polypeptide responses to glucose and polycose. In the pregnant subjects, even though the plasma insulin response to carbohydrate challenge was higher than in the nonpregnant subjects, gastric inhibitory polypeptide levels were significantly lower. Patient satisfaction was similar with both carbohydrate solutions. These data suggest that polycose can be used as a substitute for glucose in antepartum testing, although the differences in the hormonal responses should be recognized. Further studies in a subject population with carbohydrate intolerance will be required before polycose use can be recommended in abnormal states.

Fetal pleural effusion: a review and meta-analysis for prognostic indicators

We reviewed the literature on fetal pleural effusion to identify prognostic indicators related to outcome. Data on 124 cases from 38 reports were collected and analyzed using chi 2 statistical analysis and stepwise multiple logistic regression. Termination of pregnancy occurred in ten cases, spontaneous resolution occurred in 11 cases with 100% survival, and overall mortality was 46%. Gestational age at delivery of greater than 31 weeks, the absence of hydrops, and the use of antenatal therapy (thoracentesis or shunt placement) were associated with good outcome. Gender of the fetus, hydramnios, extent of effusion as unilateral or bilateral, and mode of delivery were not significantly related to outcome. Recommendations for evaluation include search for other abnormalities and possible causes related to hydrops. Management is guided by gestational age and the presence of hydrops. Antenatal therapy is recommended if hydrops develops, particularly at a gestational age of less than 32 weeks.

Diagnosis of gestational diabetes in early pregnancy

OBJECTIVE

To determine whether glucose intolerance can be identified early in gestation in a high-risk population so that early intervention can be planned to prevent associated morbidity.

RESEARCH DESIGN AND METHODS

After appropriate dietary preparation, patients with a high risk for gestational diabetes underwent a 50-g oral glucose screening test during fasting. Patients were tested on enrollment and every 10 wk until delivery. Those with a 1-h plasma glucose value of greater than or equal to 7.5 mM underwent a 100-g oral glucose tolerance test. Gestational diabetes was based on either a markedly abnormal 50-g screening test or abnormal 100-g oral glucose tolerance test.

RESULTS

Ten of 15 (66%) patients who developed gestational diabetes were diagnosed during the first half of the pregnancy. Six were diagnosed in the first trimester. If the definition of an abnormal 1-h plasma glucose value was lowered from 7.5 to 7.2 mM, an additional 2 patients could have been identified in the first trimester with an improvement in sensitivity from 70 to 91% with only a slight drop in specificity (from 91 to 88%). Diagnosis of gestational diabetes was not enhanced by measuring plasma insulin concentrations or insulin-glucose molar ratios.

CONCLUSIONS

The diagnosis of gestational diabetes in a high-risk population can be made in the first half of pregnancy. Early diagnosis should permit evaluation of intervention strategies, which may result in improved perinatal outcome.

A longitudinal study comparing the prenatal care of Puerto Rican and white women

This study examined the effect of ethnicity on health-seeking attitudes and behavior, including patient compliance, use of the clinic, knowledge of childbirth, and the relationship between the patient and primary health care provider. Anthropologic techniques of observations and interviews were conducted longitudinally with 27 Puerto Rican women and 26 white women who received perinatal care at a tertiary-level hospital throughout the antepartum, intrapartum, and postpartum periods. Approximately 500 standardized and open-ended interviews and 150 observations of clinical interactions with resident physicians and nurse-midwives compared reproductive knowledge, beliefs, and practices. Results of this three-year study indicated that both groups of women were similar in age, years of education, and percentage receiving financial assistance. Puerto Rican women identified strongly as a separate ethnic group; all spoke Spanish and most were bilingual. Office visits and explanations from primary care providers were more important to women in both groups than information obtained from families, friends, or folk beliefs. Knowledge of pregnancy care procedures and childbirth, although limited, was no different between the groups. Long waits, depersonalized service, and a lack of continuity of care adversely affected patient and physician satisfaction and diminished effective doctor-patient interactions. This study suggests that differences in ethnic background do not necessarily adversely affect the delivery of reproductive health care. Indigent white and Puerto Rican women wanted the same thing: quality perinatal care and education.

Transient maternal hypotension following epidural anesthesia

Transient maternal hypotension following regional anesthesia can lead to significantly lower umbilical cord pH values. Although this acidosis has not been found to be clinically significant, acidosis may increase the placental transfer of local anesthetic agents as a result of "ion trapping." The purpose of this study was to examine the pharmacologic and clinical consequences of transient maternal hypotension following epidural anesthesia with 0.5% bupivacaine before cesarean section. Patients were divided into two groups based on the development of maternal hypotension, defined as a systolic blood pressure less than 100 torr or a decrease of 30% or more from the preanesthetic level. Thirteen patients (33%) developed hypotension that was corrected within 2.1 +/- 1.8 min. The pH of umbilical cord venous and arterial blood and the concentration of bupivacaine were significantly lower (P less than 0.05) in neonates of mothers in the hypotensive group than in neonates of mothers that did not develop hypotension. The results show, however, that transient maternal hypotension following epidural anesthesia does not lead to a greater placental transfer of bupivacaine due to "ion trapping" even though neonatal cord blood pH decreases.

Meconium aspiration syndrome: intrapartum and neonatal attributes

To identify the fetus and newborn at risk for meconium aspiration syndrome the perinatal characteristics of 238 infants delivered through meconium-stained amniotic fluid were prospectively examined. All infants with meconium-stained amniotic fluid were routinely suctioned with a DeLee apparatus before tracheal intubation and suctioning. The type and presence of meconium in the trachea, neonatal breathing before intubation, and Apgar scores were recorded in the delivery room. Intrapartum fetal monitoring data were collected for 80% (190/238) of the mothers and umbilical artery pH for 74% (177/238) of the newborns. Despite suctioning with a DeLee apparatus and endotracheal suctioning, meconium was present in the trachea in 87/238 (37%) and meconium aspiration syndrome developed in 22 (9.2%). A total of 73% of newborns who had meconium aspiration syndrome were delivered through thick meconium. Thick meconium, the presence of fetal tachycardia, and absence of intrapartum fetal cardiac accelerations identified the fetus at high risk for meconium aspiration syndrome. The presence of these monitoring findings and thick meconium should alert obstetricians to the possibility of a fetus that requires intervention. Low umbilical artery pH, Apgar scores less than 5, and meconium in the trachea further characterized the newborn at high risk for meconium aspiration syndrome. The combination of these findings may best identify the infant delivered through meconium-stained amniotic fluid who requires close observation for meconium aspiration syndrome.

Gestational diabetes mellitus: does it recur in subsequent pregnancy?

The recurrence of glucose intolerance was examined in 36 women with an index pregnancy complicated by gestational diabetes who received antepartum care at the same institution because of a subsequent pregnancy. Standard oral or intravenous glucose tolerance tests were used to document glucose intolerance or gestational diabetes. Twenty patients had gestational diabetes in the subsequent pregnancy, whereas one third of the patients tested did not demonstrate an abnormality of carbohydrate metabolism. The patients with consecutive pregnancies complicated by gestational diabetes were heavier and were delivered of heavier neonates than the patients who did not develop gestational diabetes again. Unlike the nondiabetic group, the patients who remained gestationally diabetic weighed significantly more in the subsequent pregnancy than in the index pregnancy. These results indicate that patients with gestational diabetes should be tested in subsequent pregnancies because of the impact of gestational diabetes on birth weight. However, these results also suggest that the glucose tolerance test may not be a reliable test for the detection of abnormal carbohydrate metabolism.

2-Chloroprocaine for local perineal infiltration

Lidocaine was recently found to rapidly cross the placenta and result in considerable fetal exposure after local infiltration of the perineum for episiotomy. For this reason, a more appropriate agent for local perineal infiltration might be a drug with rapid metabolism and inactive metabolites. 2-Chloroprocaine, an ester-linked local anesthetic agent, is available but is not commonly used for this procedure. The purpose of this study was to evaluate the placental transfer of 2-chloroprocaine after local perineal infiltration. The drug was administered to 17 normal term pregnant women for episiotomy. After local perineal infiltration, the levels of 2-chloroprocaine and/or its metabolite, chloroaminobenzoic acid, were quantitated in maternal and neonatal plasma or urine. The pharmacologic data indicated that 2-chloroprocaine was nondetectable at delivery in maternal and umbilical cord vein; one patient had trace levels in the cord. Chloroprocaine was not detectable in neonatal plasma, but chloroaminobenzoic acid was detectable in both maternal and cord vein plasma. Mean levels of chloroaminobenzoic acid in maternal plasma at delivery were 1.04 +/- 0.32 micrograms/ml, and mean levels in cord vein were 0.35 +/- 0.54 micrograms/ml. Clinically, 2-chloroprocaine provided good analgesia. These results indicate that very little, if any pharmacologically active drug, reaches the fetus after local perineal infiltration with 2-chloroprocaine. Therefore 2-chloroprocaine appears to be preferable to lidocaine when used for local perineal infiltration.

Effects of maternal glucose infusion on fetal acid-base status in human pregnancy

The maternal and fetal metabolic effects of three commonly used intravenous fluids administered before regional anesthesia were studied in 32 gravid women undergoing elective cesarean section at term. Patients were randomized into one of three groups to receive 1 L of either 5% dextrose (50 gm of glucose) or Ringer's lactate or isotonic saline solution before epidural anesthesia. Acute glucose infusion resulted in maternal hyperglycemia, hyperinsulinemia, and an increase in the blood lactate level. Cord blood glucose, insulin, and lactate levels were also increased in this group. The key finding of this study was the significant lowering of pH in the umbilical cord vein (7.31 +/- 0.04) and artery (7.21 +/- 0.06) in the glucose-infused group when compared with the non-glucose infusion groups (p less than 0.05). Confounding perinatal factors such as maternal position, maternal hypotension, and prolonged time of surgery did not influence the fetal acid-base status. Thus acute maternal glucose infusion in normal patients can cause fetal hyperglycemia, metabolic acidosis, and neonatal hypoglycemia. These findings may be of particular clinical importance when fetal distress or fetal hypoxemia is due to other perinatal events. Under these circumstances, acute maternal glucose infusion may further contribute to fetal metabolic acidosis.

The half-life of 2-chloroprocaine

The purpose of this study was to examine the discrepancy between the reported in vitro half-life of chloroprocaine and the slower observed disappearance of the drug in maternal plasma. The study had two aims. The first was to redetermine the in vitro half-life of 2-chloroprocaine in maternal and fetal plasma. The second was to determine the apparent half-life of 2-chloroprocaine in vivo after intrapartum epidural anesthesia in obstetric patients. Gas chromatography or gas chromatography/mass spectrometry techniques were used to measure 2-chloroprocaine in maternal or fetal plasma. Mean in vitro half-lives of 11.2 +/- 2.8 and 15.4 +/- 5.2 sec were found for maternal and fetal plasma from nine patients, respectively. The maternal half-life was significantly shorter than the fetal half-life (P less than 0.05). The mean apparent in vivo half-life in maternal plasma was found to be 3.1 +/- 1.6 min. The results of this study show that the half-life in vitro is correctly measured in seconds. However, the apparent half-life in vivo after epidural anesthesia is 3.1 +/- 1.6 min and ranges from 1.5 to 6.4 min. The differences in the magnitude of the two findings is probably due to continuous uptake of the drug from the epidural space.

Lidocaine disposition in mother, fetus, and neonate after spinal anesthesia

Although it is generally believed that concentrations of local anesthetic in maternal plasma do not reach levels that affect the fetus after spinal anesthesia, there are few studies that have measured drug levels in either maternal or neonatal plasma after spinal anesthesia. The purpose of this study was to document the disposition of lidocaine in mother, fetus, and neonate after spinal anesthesia using gas chromatographic/mass spectrometric measurement of lidocaine and two metabolites of lidocaine. Plasma concentration time curves, fetal/maternal ratios, cord artery/cord vein ratios, and neonatal urine levels were determined in ten patients. The results document that lidocaine is present in maternal and neonatal plasma. Mean (+/- SD) maternal plasma levels (0.65 +/- 0.52 micrograms/ml) were significantly lower than those previously reported after epidural anesthesia (2.09 +/- 1.31 micrograms/ml). Fetal/maternal plasma concentration ratios averaged 0.37 +/- 0.2 and mean cord arterial/cord venous ratios 0.5 +/- 6.7. Lidocaine and its metabolites were present in neonatal urine for longer than 36 hr. This study demonstrates that spinal anesthesia with lidocaine results in neonatal exposure to lidocaine.

Trends in the frequency of cesarean births

While the actual cesarean birth rate may still be increasing, it appears that the rate of increase is not as extreme. Perhaps this can be expressed as a trend. A recent study has demonstrated the ability to decrease the primary cesarean section rate without adverse perinatal effects. Confirmation that the cesarean birth rate is not necessarily linked to perinatal mortality is available from the Dublin report, in which the authors note that the trend in cesarean birth rates can be altered by a different approach to the management of labor. While still speculative, it appears that public concern and physician attitudes may soon be reflected in a trend toward decreasing cesarean birth rates.

Maternal obesity as a risk factor in gestational diabetes

Maternal obesity has been associated with both gestational diabetes mellitus (GDM) and neonatal macrosomia. Most studies of obesity in pregnancy have demonstrated an increased risk for GDM. However, the contribution of obesity as an added risk in GDM has not been examined. The purpose of this study was to examine the contribution of obesity as a risk factor to perinatal morbidity in gestationally diabetic women by comparing the maternal and neonatal outcome in obese and nonobese gestationally diabetic women. From 1979 to 1983, the maternal, intrapartum, and neonatal characteristics of all prepartum gravid patients with GDM were examined. Of the 158 patients with documented GDM, 62 (39%) were obese (weight greater than 90 kg). There was no difference in maternal age (obese 29.3 +/- 5.4 years, nonobese 28.7 +/- 6.5 years) parity, or prepartum risk score between the obese and nonobese patients. The incidence of prematurity, pre-eclampsia, fetal distress, and primary cesarean sections were not different between the groups. There were no differences in Apgar scores, gestational age, or perinatal morbidity. However, the obese patients delivered heavier neonates expressed as mean birthweight (obese 3667 +/- 682 gms, nonobese 3331 +/- 750 gms. P less than .01), the number of macrosomic (greater than 4 kg) neonates (obese 37%, nonobese 14%, P less than .001) and K-score, (obese 0.8 +/- 1, nonobese 0.4 +/- 9, P less than .05). These data indicate that obese patients with GDM have an increased risk of neonatal macrosomia.(ABSTRACT TRUNCATED AT 250 WORDS)

Gestational diabetes mellitus. Is further improvement necessary?

The maternal antepartum, intrapartum, and neonatal characteristics of 158 patients with gestational diabetes mellitus (GDM) attending a large teaching hospital between 1979 and 1983 were described and compared with a matched nondiabetic control group. The primary cesarean section rate in patients with GDM (18%) was significantly greater than in the control group (11%, P less than 0.04). Neonatal macrosomia, as reflected in mean birthweight (P less than 0.04), the number of neonates weighing greater than 4 kg (P less than 0.05) and large-for-gestational-age infants (P less than 0.05), and the birthweight adjusted for gestational age (K-score, P less than 0.01) was significantly increased in the diabetic group. The characteristics of patients with GDM treated with diet alone and diet and insulin together were examined. The insulin-therapy group was characterized by more patients older than 25 yr (P less than 0.01) and a higher mean birthweight (3743 +/- 677 g) (P less than 0.02) than the diet-alone group. This may reflect an increased magnitude of glucose intolerance in the insulin-treated group. Obese patients with GDM delivered heavier neonates than the nonobese patients with GDM (P less than 0.01). Although there was no difference between the groups, perinatal mortality was present in this study. These data indicate that the major perinatal morbidity in GDM included increased cesarean section for fetal macrosomia. Early diagnosis with strict diagnostic criteria and rigid antenatal surveillance may result in further improvements in outcome.

Disposition of meperidine and normeperidine following multiple doses during labor. II. Fetus and neonate

It has been suggested that continued diffusion gradients from mother to fetus would exist and that both meperidine and normeperidine would accumulate in the fetus following multiple doses of meperidine to the mother during labor. However, no pharmacokinetic data are available. Therefore, the purpose of this study was to document the disposition of meperidine and normeperidine in the fetus and neonate following multiple doses of meperidine to the mother over long time periods. Twelve infants were studied. The results show surprisingly high concentrations of both meperidine and normeperidine in fetal blood at delivery. In addition, the amount of normeperidine increased with time in umbilical cord blood, the ratio of normeperidine to meperidine increased with time, and the umbilical artery-to-vein ratio of meperidine (but not normeperidine) was greater than one following long drug-to-delivery intervals. The data also suggest that with long drug-to-delivery intervals the levels of normeperidine may become clinically important and that the elimination of both compounds by the neonate is prolonged. The study suggests that multiple doses to the mother over long time periods result in maximum accumulation of both meperidine and normeperidine in fetal tissues.

Disposition of meperidine and normeperidine following multiple doses during labor. I. Mother

Normeperidine, the active meperidine metabolite, has been implicated in adverse neonatal effects that may occur following administration of meperidine to parturients. However, recent studies have suggested that normeperidine levels are not high enough to have adverse effects following single low doses of meperidine. It is not clear what occurs following multiple injections. Therefore the purpose of this study was to quantitate plasma levels of meperidine and normeperidine in the mother following multiple doses of meperidine over long time periods and to determine the half-life of normeperidine. Twelve mothers who received multiple intravenous doses of meperidine were studied. The results show that both meperidine and normeperidine accumulate in maternal plasma following multiple injections and that the half-life of normeperidine averages 20.6 hours. The data suggest that maximum exposure of the fetus to both meperidine and normeperidine would result from multiple doses to the mother because of a continued diffusion gradient from mother to fetus.

Fetal acidosis, 2-chloroprocaine, and epidural anesthesia for cesarean section

Amide-linked local anesthetic agents, such as lidocaine and bupivacaine, can become "trapped" in their ionized forms on the fetal side of the placenta, and therefore their net transfer across the placenta is increased. An ester-linked local anesthetic agent, 2-chloroprocaine, is rapidly metabolized, and placental transfer is limited. Since the metabolism of 2-chloroprocaine by fetal plasma is slower than in maternal plasma, the potential for ion trapping exists. The purpose of this study was to determine the disposition of 2-chloroprocaine and its metabolite, chloroaminobenzoic acid, in relation to the umbilical cord vein pH at delivery, and specifically, to determine whether ion trapping exists. Epidural anesthesia with 2-chloroprocaine was administered to 44 women at term prior to cesarean section. At delivery the levels of 2-chloroprocaine and chloroaminobenzoic acid in maternal plasma and umbilical cord vein were quantitated. Neonates were divided into two groups based on the umbilical cord vein pH at delivery. Ten of the 44 patients delivered neonates with a pH less than or equal to 7.25 (acidotic group) while 34 delivered neonates with a pH greater than 7.25 (nonacidotic group). The mean umbilical cord vein pH in the acidotic and nonacidotic groups was 7.22 +/- 0.03 and 7.32 +/- 0.03, respectively (p less than 0.001). There were also no differences between the groups in maternal and neonatal clinical characteristics or in the total dose of 2-chloroprocaine administered or the drug-to-delivery interval. The pharmacologic results did not demonstrate a statistical difference in the concentration of 2-chloroprocaine or chloroaminobenzoic acid in the maternal vein or umbilical cord vein at delivery between the two groups. Thus the results of this study demonstrate that placental transfer of 2-chloroprocaine is not influenced by fetal acidosis. Therefore these data suggest that 2-chloroprocaine may be the drug of choice when fetal acidosis or distress is anticipated.

Maternal, fetal, and neonatal lidocaine levels following local perineal infiltration

Local infiltration of the perineum is a simple and commonly used technique for providing pain relief for episiotomy. It has always been considered safe and effective because a small amount of local anesthetic agent could be administered quickly and accurately to the perineum just prior to vaginal delivery and cord clamping. Because of the short time interval between local infiltration and delivery, very little anesthetic was thought to reach the fetus. However, the maternal and neonatal disposition of lidocaine following local perineal infiltration has not been well studied. The purpose of this study was to document placental transfer or nontransfer of lidocaine following local perineal infiltration. Fifteen normal parturient women at term and their infants were studied. After local perineal infiltration, the concentrations of lidocaine and two metabolites--monoethyl glycine xylidide and glycine xylidide --were determined in maternal plasma, in the umbilical cord vein at delivery, and in maternal and neonatal plasma or urine for 2 days post partum. Lidocaine and its metabolites were quantitated by gas chromatography-mass spectrometry. The pharmacologic results indicated the following: First, lidocaine is detected in maternal plasma as early as 1 minute after injection, and peak plasma concentrations occur within 3 to 15 minutes. Second, there is rapid placental transfer of lidocaine; the mean fetal/maternal ratio of 1.32 was significantly higher than that found following epidural anesthesia. Third, lidocaine and its active metabolites persisted in neonatal urine for at least 48 hours after delivery. This study suggests that local perineal infiltration with lidocaine for episiotomy should be considered similar to any other anesthetic technique in that it may result in significant neonatal drug exposure.

Maternal and neonatal elimination of CABA after epidural anesthesia with 2-chloroprocaine during parturition

Little is known about the pharmacology of the metabolites of 2-chloroprocaine in obstetrical patients. The primary objective of this study was to describe the elimination of 2-chloroaminobenzoic acid (CABA) in maternal and neonatal urine after epidural anesthesia. A secondary objective was to compare its elimination in patients with preterm and term deliveries. The study included 21 pregnant women and their offspring. The mean gestational age of the 11 preterm infants was 34 +/- 3 weeks and that of the 10 term infants was 40 +/- 2 weeks. Maternal and cord venous blood samples were obtained at delivery and 12-hr urine samples for 72 hr postpartum. Blood and urine samples were analyzed for CABA by gas chromatography using electron capture detection. Both mothers and neonates excreted considerable amounts of unchanged CABA, and mothers also excreted CABA in a conjugated form. Mean elimination rate constants were 0.263 +/- 0.193 mg X hr-1 for mothers and 0.129 +/- 0.035 micrograms X hr-1 for neonates. Over 95% of the CABA recovered from the mothers and neonates was excreted by 36 hr postpartum. Mothers excreted 40% of the administered 2-chloroprocaine as CABA and neonates excreted 0.22-0.25% of the maternal dose as CABA. No differences in elimination due to the length of gestation were found in the mothers or neonates. Although mothers excrete CABA more rapidly than neonates, the results of this study suggest that both effectively excrete CABA.

Oligohydramnios: clinical associations and predictive value for intrauterine growth retardation

Intrauterine growth retardation (IUGR) is difficult to diagnose before birth. Sonographically diagnosed oligohydramnios has been reported to be highly sensitive and reliable in detecting IUGR in carefully prescreened patients. To evaluate the clinical associations of oligohydramnios and its usefulness as a method of antenatal screening for IUGR on a large obstetric service, the consecutive ultrasound examinations of 2,453 viable singleton pregnancies with intact membranes were surveyed. The 96 (3.9%) pregnancies found to be complicated by oligohydramnios were compared with 96 with the same biparietal diameters, but with normal volumes of amniotic fluid. Mothers with oligohydramnios were younger, of lower parity, and at increased clinical risk for IUGR. Of 96 infants from oligohydramnios-complicated pregnancies, 38 (40%) were small for gestational age (SGA), compared with eight (8%) infants from pregnancies without oligohydramnios. Of 46 SGA births, 38 (83%) were preceded by sonographically diagnosed oligohydramnios (p less than 0.0001). IUGR associated with oligohydramnios tended to occur in young hypertensive gravid women, whereas non-oligohydramnios-associated IUGR tended to occur in gravid women with low prepregnancy weight. With correction for the incidences of oligohydramnios and IUGR in the unselected population, it is shown that four in 10 cases of oligohydramnios would result in SGA births (40% predictive value of an abnormal test), but that only 16% of SGA births would be preceded by sonographically diagnosed oligohydramnios. Eighty-four percent of the cases would be missed. These results suggest that, although the presence of oligohydramnios should increase the clinician's index of suspicion for IUGR, routine sonographic screening to detect oligohydramnios is not warranted.

Intrapartum paracervical block anesthesia with 2-chloroprocaine

Most of the reports of fetal bradycardia and acidosis following paracervical block anesthesia have involved the use of amide-linked anesthetics, such as lidocaine and mepivacaine. The purposes of this study were (1) to determine placental transfer of an ester-linked local anesthetic, 2-chloroprocaine, and its inactive metabolite, 2-chloroaminobenzoic acid (CABA) following paracervical block and (2) to evaluate the clinical use of 2-chloroprocaine for paracervical block anesthesia. Accordingly, 2-chloroprocaine was administered to 16 normal pregnant women in labor at term. Following injection, the levels of 2-chloroprocaine or CABA in maternal and neonatal plasma or urine were quantitated. Multiple clinical parameters, including the presence or absence of fetal bradycardia, were monitored before and after the paracervical block. The pharmacologic data indicated that 2-chloroprocaine is rapidly hydrolyzed. At delivery only trace levels of 2-chloroprocaine were present in 6.3% of the maternal samples and 25% of the cord vein samples. Furthermore, only 0.24% of the total dose of 2-chloroprocaine administered was recovered in neonatal urine as CABA. The clinical data showed no adverse effects on the parturient or neonate. Therefore, the data suggest that paracervical block anesthesia with 2-chloroprocaine may offer safe analgesia during the first stage of labor. Larger clinical studies appear warranted.