Prepregnancy maternal body mass index and venous thromboembolism: a population-based cohort study

OBJECTIVE

To assess the relation between maternal body mass index (BMI) and pregnancy-related venous thromboembolism (VTE).

DESIGN

Cohort study.

SETTING AND POPULATION

A total of 2 449 133 women with singleton pregnancies who underwent delivery hospitalisation in California between 2008 and 2012.

METHODS

Association of pre-pregnancy BMI and the risk of an antepartum and postpartum VTE was examined using logistic regression, with normal BMI as reference.

MAIN OUTCOME MEASURES

Antepartum and postpartum VTE-related hospitalisation.

RESULTS

The prevalence of antepartum and postpartum VTE increased with increasing BMI (antepartum: 2.3, 3.0, 3.8, 4.2, 4.7, and 10.6 per 10 000 women for underweight, normal BMI, overweight, obesity class I, II, and III, respectively, P < 0.001; postpartum: 2.0, 3.1, 3.9, 5.6, 9.0, and 13.2 per 10 000 women, P < 0.01). The adjusted odds of antepartum and postpartum VTE increased progressively with increasing BMI, with obesity class III women having the highest risk of pregnancy-related VTE compared with normal BMI women: adjusted odds ratio for antepartum VTE: 2.9; 95% CI 2.2-3.8 and adjusted odds ratio for postpartum VTE: 3.6; 95% CI 2.9-4.6.

CONCLUSIONS

Our findings clearly demonstrate an increasing risk of pregnancy-related VTE with increasing BMI.

TWEETABLE ABSTRACT

Obesity was associated with increased odds of antepartum and postpartum venous thromboembolism.

Utility of third trimester sonographic measurements for predicting SGA in cases of fetal gastroschisis

OBJECTIVE

To assess the accuracy of different sonographic estimated fetal weight (EFW) cutoffs, and combinations of EFW and biometric measurements for predicting small for gestational age (SGA) in fetal gastroschisis.

STUDY DESIGN

Gastroschisis cases from two centers were included. The sensitivity, specificity, positive and negative predictive values (PPV and NPV) were calculated for different EFW cutoffs, as well as EFW and biometric measurement combinations.

RESULTS

Seventy gastroschisis cases were analyzed. An EFW<10% had 94% sensitivity, 43% specificity, 33% PPV and 96% NPV for SGA at delivery. Using an EFW cutoff of <5% improved the specificity to 63% and PPV to 41%, but decreased the sensitivity to 88%. Combining an abdominal circumference (AC) or femur length (FL) z-score less than -2 with the total EFW improved the specificity and PPV but decreased the sensitivity.

CONCLUSION

A combination of a small AC or FL along with EFW increases the specificity and PPV, but decreases the sensitivity of predicting SGA.

Obstetric interventions and maternal morbidity among women who experience severe postpartum hemorrhage during cesarean delivery

BACKGROUND

Compared to vaginal delivery, women undergoing cesarean delivery are at increased risk of postpartum hemorrhage. Management approaches may differ between those undergoing prelabor cesarean delivery compared to intrapartum cesarean delivery. We examined surgical interventions, blood component use, and maternal outcomes among those experiencing severe postpartum hemorrhage within the two distinct cesarean delivery cohorts.

METHODS

We performed secondary analyses of data from two cohorts who underwent prelabor cesarean delivery or intrapartum cesarean delivery at a tertiary obstetric center in the United States between 2002 and 2012. Severe postpartum hemorrhage was classified as an estimated blood loss ≥1500mL or receipt of a red blood cell transfusion up to 48h post-cesarean delivery. We examined blood component use, medical and surgical interventions and maternal outcomes.

RESULTS

The prelabor cohort comprised 269 women and the intrapartum cohort comprised 278 women. In the prelabor cohort, one third of women received red blood cells intraoperatively or postoperatively, respectively. In the intrapartum cohort, 18% women received red blood cells intraoperatively vs. 44% postoperatively (P<0.001). In the prelabor and intrapartum cohorts, methylergonovine was the most common second-line uterotonic (33% and 43%, respectively). Women undergoing prelabor cesarean delivery had the highest rates of morbidity, with 18% requiring hysterectomy and 16% requiring intensive care admission.

CONCLUSION

Our findings provide a snapshot of contemporary transfusion and surgical practices for severe postpartum hemorrhage management during cesarean delivery. To determine optimal transfusion and management practices in this setting, large pragmatic studies are needed.

Maternal characteristics and mid-pregnancy serum biomarkers as risk factors for subtypes of preterm birth

OBJECTIVE

To examine the relationship between maternal characteristics, serum biomarkers and preterm birth (PTB) by spontaneous and medically indicated subtypes.

DESIGN

Population-based cohort.

SETTING

California, United States of America.

POPULATION

From a total population of 1 004 039 live singleton births in 2009 and 2010, 841 665 pregnancies with linked birth certificate and hospital discharge records were included.

METHODS

Characteristics were compared for term and preterm deliveries by PTB subtype using logistic regression and odds ratios adjusted for maternal characteristics and obstetric factors present in final stepwise models and 95% confidence intervals. First-trimester and second-trimester serum marker levels were analysed in a subset of 125 202 pregnancies with available first-trimester and second-trimester serum biomarker results.

MAIN OUTCOME MEASURE

PTB by subtype.

RESULTS

In fully adjusted models, ten characteristics and three serum biomarkers were associated with increased risk in each PTB subtype (Black race/ethnicity, pre-existing hypertension with and without pre-eclampsia, gestational hypertension with pre-eclampsia, pre-existing diabetes, anaemia, previous PTB, one or two or more previous caesarean section(s), interpregnancy interval ≥ 60 months, low first-trimester pregnancy-associated plasma protein A, high second-trimester α-fetoprotein, and high second-trimester dimeric inhibin A). These risks occurred in 51.6-86.2% of all pregnancies ending in PTB depending on subtype. The highest risk observed was for medically indicated PTB <32 weeks in women with pre-existing hypertension and pre-eclampsia (adjusted odds ratio 89.7, 95% CI 27.3-111.2).

CONCLUSIONS

Our findings suggest a shared aetiology across PTB subtypes. These commonalities point to targets for further study and exploration of risk reduction strategies.

TWEETABLE ABSTRACT

Findings suggest a shared aetiology across preterm birth subtypes. Patterns may inform risk reduction efforts.

Mode of anaesthesia for preterm Caesarean delivery: secondary analysis from the Maternal-Fetal Medicine Units Network Caesarean Registry

BACKGROUND

Preterm delivery is often performed by Caesarean section. We investigated modes of anaesthesia and risk factors for general anaesthesia among women undergoing preterm Caesarean delivery.

METHODS

Women undergoing Caesarean delivery between 24(+0) and 36(+6) weeks' gestation were identified from a multicentre US registry. The mode of anaesthesia was classified as neuraxial anaesthesia (spinal, epidural, or combined spinal and epidural) or general anaesthesia. Logistic regression was used to identify patient characteristic, obstetric, and peripartum risk factors associated with general anaesthesia.

RESULTS

Within the study cohort, 11 539 women had preterm Caesarean delivery; 9510 (82.4%) underwent neuraxial anaesthesia and 2029 (17.6%) general anaesthesia. In our multivariate model, African-American race [adjusted odds ratio (aOR)=1.9; 95% confidence interval (CI)=1.7-2.2], Hispanic ethnicity (aOR=1.5; 95% CI=1.2-1.8), other race (aOR=1.4; 95% CI=1.1-1.9), and haemolysis, elevated liver enzymes and low platelets (HELLP) syndrome or eclampsia (aOR=2.8; 95% CI=2.2-3.5) were independently associated with receiving general anaesthesia for preterm Caesarean delivery. Women with an emergency Caesarean delivery indication had the highest odds for general anaesthesia (aOR=3.5; 95% CI=3.1-3.9). For every 1 week decrease in gestational age at delivery, the adjusted odds of general anaesthesia increased by 13%.

CONCLUSIONS

In our study cohort, nearly one in five women received general anaesthesia for preterm Caesarean delivery. Although potential confounding by unmeasured factors cannot be excluded, our findings suggest that early gestational age at delivery, emergent Caesarean delivery indications, hypertensive disease, and non-Caucasian race or ethnicity are associated with general anaesthesia for preterm Caesarean delivery.

Magnesium sulfate exposure and neonatal intensive care unit admission at term

OBJECTIVE

The aim of this study was to investigate the effect of maternal magnesium sulfate (MgSO4) exposure for eclampsia prophylaxis on neonatal intensive care unit (NICU) admission rates for term newborns.

STUDY DESIGN

A secondary analysis of the Maternal-Fetal Medicine Unit Network Cesarean Registry, including primary and repeat cesarean deliveries, and failed and successful trials of labor after cesarean was conducted. Singleton pregnancies among women with preeclampsia and >37 weeks of gestation were included. Pregnancies with uterine rupture, chorioamnionitis and congenital malformations were excluded. Logistic regression analysis was used to determine associations between MgSO4 exposure and NICU admission. P<0.05 was considered statistically significant.

RESULT

Two thousand one hundred and sixty-six term pregnancies of women with preeclampsia were included, of whom 1747 (81%) received MgSO4 for eclampsia prophylaxis and 419 (19%) did not. NICU admission rates were higher among newborns exposed to MgSO4 vs unexposed (22% vs 12%, P<0.001). After controlling for neonatal birth weight, gestational age and maternal demographic and obstetric factors, NICU admission remained significantly associated with antenatal MgSO4 exposure (adjusted odds ratio 1.9, 95% confidence interval 1.3 to 2.6, P<0.001). Newborns exposed to MgSO4 were more likely to have Apgar scores <7 at 1 and 5 min (15% vs 11% unexposed, P=0.01 and 3% vs 0.7% unexposed, P=0.008). There were no significant differences in NICU length of stay (median 5 (range 2 to 91) vs 6 (3 to 15), P=0.5).

CONCLUSION

Antenatal maternal MgSO4 treatment was associated with increased NICU admission rates among exposed term newborns of mothers with preeclampsia. This study highlights the need for studies of maternal MgSO4 administration protocols that optimize maternal and fetal benefits and minimize risks.

Risk factors for obstetric morbidity in patients with uterine atony undergoing caesarean delivery

BACKGROUND

Uterine atony (UA) is recognized as a leading cause of postpartum haemorrhage. However, knowledge of risk factors of haemorrhage-related morbidity among patients diagnosed with UA is uncertain. We investigated risk factors for haemorrhage-related morbidity among patients undergoing Caesarean delivery with UA.

METHODS

We conducted a secondary analysis of data sourced from a 4-yr observational study at 19 US academic centres. Patients with UA were identified based on receiving methylergonovine or carboprost. Our primary outcome (haemorrhage-related morbidity) included a composite of intra- or postpartum transfusion; Caesarean hysterectomy; uterine or hypogastric artery ligation; intensive care admission for: pulmonary oedema, coagulopathy, adult respiratory distress syndrome, postoperative ventilation, or invasive line monitoring.

RESULTS

Among 57,182 patients who underwent Caesarean delivery, 2294 (4%) patients developed UA. Haemorrhage-related morbidity occurred in 450 (19.6%) patients with UA. The risk of haemorrhage-related morbidity was increased among African-Americans [adjusted odds ratio (aOR)=2.36; 95% confidence interval (CI)=1.73-3.23], Hispanics (aOR=1.4; 95% CI=1.04-1.9), women with multiple gestations (aOR=1.59; 95% CI=1.06-2.38), placenta praevia (aOR=4.89; 95% CI=3.04-7.87), patients with ASA class III (aOR=1.4; 95 CI=1.03-1.9), or ASA class IV (aOR=5.88; 95% CI=2.48-13.9), exposure to general anaesthesia (GA) (aOR=2.4; 95% CI=1.59-3.62) and combined general and regional anaesthesia (aOR=4.0; 95% CI=2.62-6.09), and ≥2 prior Caesarean deliveries (aOR=1.62; 95% CI=1.1-2.39).

CONCLUSIONS

Among patients with UA undergoing Caesarean delivery, the risk of haemorrhage-related morbidity is increased in African-Americans, Hispanics, patients with multiple gestations, placenta praevia, ASA class III or IV, ≥2 prior Caesarean deliveries and those undergoing GA.

Effect of magnesium sulfate exposure on term neonates

OBJECTIVE

To compare neonatal intensive care unit and special care unit (NICU) admission rates between term neonates exposed to antenatal magnesium sulfate (MS) and those unexposed.

STUDY DESIGN

We performed a retrospective cohort study of all singleton neonates ≥37 weeks born to women with pre-eclampsia from August 2006 to July 2008. Cases were defined by antenatal exposure to MS and controls by absence of MS exposure. The primary outcome was NICU admission. Data were analyzed via univariable and multivariable regression analyses.

RESULT

In all, 28 (14.7%) out of 190 MS-exposed neonates ≥37 weeks were admitted to the NICU, compared with 4 (5.4%) of 74 non-exposed neonates (P=0.04). This association persisted after controlling for potential confounding variables including severe pre-eclampsia and cesarean delivery (AOR 3.69, 1.13 to 11.99). NICU admission was associated in a dose-dependent relationship with total hours and mean dose of MS exposure. Number needed to harm with MS was 11 per NICU admission. Among neonates admitted to the NICU, MS-exposed were more likely to require fluid and nutritional support than unexposed neonates (60.7 vs 0%, P=0.04), and trended toward more frequent requirement for respiratory support and greater length of stay.

CONCLUSION

In term neonates, MS exposure may be associated independently with NICU admission in a dose-dependent relationship. Requirements for fluid and nutritional support are common in this group, likely due to feeding difficulties in exposed neonates. Assessment of acute care needs among all neonates exposed to MS for maternal eclampsia prophylaxis should be considered.

Single- versus double-layer hysterotomy closure at primary caesarean delivery and bladder adhesions

OBJECTIVE

To determine the association between single-layer (one running suture) and double-layer (second layer or imbricating suture) hysterotomy closure at primary caesarean delivery and subsequent adhesion formation.

DESIGN

A secondary analysis from a prospective cohort study of women undergoing first repeat caesarean section.

SETTING

Department of Obstetrics and Gynecology, Stanford University, Stanford, CA, USA.

POPULATION

One hundred and twenty-seven pregnant women undergoing first repeat caesarean section.

METHODS

Patient records were reviewed to identify whether primary caesarean hysterotomies were closed with a single or double layer. Data were analysed by Fisher's exact tests and multivariable logistic regression.

MAIN OUTCOME MEASURE

Prevalence rate of pelvic and abdominal adhesions.

RESULTS

Of the 127 women, primary hysterotomy closure was single layer in 56 and double layer in 71. Single-layer hysterotomy closure was associated with bladder adhesions at the time of repeat caesarean (24% versus 7%, P = 0.01). Single-layer closure was associated in this study with a seven-fold increase in the odds of developing bladder adhesions (odds ratio, 6.96; 95% confidence interval, 1.72-28.1), regardless of other surgical techniques, previous labour, infection and age over 35 years. There was no association between single-layer closure and other pelvic or abdominal adhesions.

CONCLUSIONS

Primary single-layer hysterotomy closure may be associated with more frequent bladder adhesions during repeat caesarean deliveries. The severity and clinical implications of these adhesions should be assessed in large prospective trials.

Delivery mode by race for breech presentation in the US

OBJECTIVE

To determine if there are differential cesarean delivery rates by race and other socio-demographic factors for women with breech infants.

STUDY DESIGN

We calculated cesarean delivery rates for 186 727 White, African American, Hispanic and Asian women delivering breech singletons with gestational age 26 to 41 weeks born in 1999 and 2000 using data from the National Center for Health Statistics. Multivariable logistic regression was used to determine differences in mode of delivery by race, adjusting for socio-demographic and medical factors.

RESULTS

Cesarean rates for breech were >80% in most gestational age groups. In 14 of 18 groups, Whites had higher cesarean delivery rates than African Americans. However, this finding did not persist after risk adjustment. Hispanics were more likely to deliver by cesarean delivery than African Americans and Whites.

CONCLUSION

Breech singleton infants are predominantly born by cesarean delivery. Although African-American women with breech presentation have lower cesarean delivery rates than Whites, this difference is not present after adjusting for socio-demographic and medical factors. Hispanics were more likely to be delivered by cesarean delivery and this difference was amplified after risk adjustment. Asians had slightly lower cesarean rates after risk adjustment, but this varied widely according to Asian subgroup.

Central nervous system lupus and pregnancy: 11-year experience at a single center

OBJECTIVE

To describe the pregnancy outcomes in women with central nervous system (CNS) manifestations of lupus.

METHODS

Between 1991 and 2002, the outcome of five pregnancies in four patients with CNS lupus were retrospectively reviewed. All patients had an established history of systemic lupus erythematosus (SLE), and either a history of CNS lupus or active CNS lupus. Pregnancy outcomes assessed included term and preterm birth, intrauterine growth restriction, abnormal antepartum testing, perinatal mortality, pre-eclampsia and other maternal morbidities.

RESULTS

Evidence of active CNS lupus symptoms developed in three of the five pregnancies. Two pregnancies were complicated by early onset pre-eclampsia, abnormal antepartum testing and extreme prematurity, with one subsequent neonatal death. The remaining three pregnancies had good neonatal outcomes, but were complicated by severe maternal post-pregnancy exacerbations, and the eventual death of one patient.

CONCLUSIONS

CNS lupus in pregnancy represents an especially severe manifestation of SLE, and may involve great maternal and fetal risks.

Does nifedipine prevent the tachysystole associated with misoprostol induction?

OBJECTIVE

To determine the efficacy of oral nifedipine as prophylaxis against uterine tachysystole associated with misoprostol induction of labor.

METHODS

A total of 116 patients undergoing induction with term, singleton pregnancies were enrolled. All patients received 50 microg misoprostol intravaginally every 4 h. Patients were randomly assigned also to receive nifedipine 10 mg orally every 4 h, or no prophylaxis. The primary outcome variable was the incidence of 12 or more contractions in any 20-min interval.

RESULTS

Data on 106 patients were available for analysis. There were 55 subjects in the misoprostol-nifedipine group and 51 controls. Nifedipine did not diminish the incidence of tachysystole when added to misoprostol (42% vs. 45% without nifedipine; p = 0.7).

CONCLUSION

Prophylactic oral nifedipine was not shown to decrease the uterine tachysystole associated with vaginal misoprostol induction at a 50-microg dose.

Fetal ear length measurement: a useful predictor of aneuploidy?

OBJECTIVE

To determine the usefulness of short ear length (EL) measurement in the prenatal detection of fetuses with chromosomal abnormalities.

DESIGN

Fetal EL measurements, routine biometry and complete anatomic survey for fetal abnormalities were prospectively performed by antenatal sonography.

SUBJECTS

One thousand eight hundred and forty-eight patients with singleton pregnancies undergoing genetic amniocentesis in the second or third trimester.

METHODS

Complete data for EL, biometry and anatomic survey for major structural abnormalities and minor sonographic markers of chromosomal abnormality were available in 1311 fetuses. Of these, 48 (3.7%) had an abnormal karyotype and 1263 (96.3%) had a normal karyotype. Using an EL measurement of < or = 10th percentile for corresponding gestational age in normal fetuses as abnormal cut-off values, detection rates for chromosomal abnormalities by short EL were determined.

RESULTS

Among the 48 abnormal karyotypes, 34 were considered significant, and 11 of these 34 (32.4%) fetuses had short EL. In 14 cases, the karyotypic abnormality was considered non-significant and fetal EL was normal in all cases. Of the 34 fetuses with significant chromosomal abnormalities, six (17.6%) on antenatal sonography had no detectable abnormal findings, other than short EL. An increased biparietal diameter (BPD)/EL ratio of > or = 4.0 was also noted in fetuses with an abnormal karyotype, but the sensitivity and predictive value of increased BPD/EL ratio alone or increased BPD/EL ratio in combination with short EL was no better than the sensitivity and predictive value of short EL alone. A combination of short EL and abnormal ultrasound, however, gave a much higher positive predictive value (46%) for significant chromosomal abnormalities.

CONCLUSIONS

Our findings suggest that in women at high risk for fetal chromosomal abnormality, a short fetal EL measurement on prenatal ultrasound, either alone or in combination with other sonographically detectable structural abnormalities, may be a useful parameter in predicting fetal aneuploidy.

Cost-effectiveness of a trial of labor after previous cesarean

OBJECTIVE

To determine the cost-effective method of delivery, from society's perspective, in patients who have had a previous cesarean.

METHODS

We completed an incremental cost-effectiveness analysis of a trial of labor relative to cesarean using a computerized model for a hypothetical 30-year old parturient. The model incorporated data from peer-reviewed studies, actual hospital costs, and utilities to quantify health-related quality of life. A threshold of $50,000 per quality-adjusted life-years was used to define cost-effective.

RESULTS

The model was most sensitive to the probability of successful vaginal delivery. If the probability of successful vaginal birth after cesarean (VBAC) was less than 0.65, elective repeat cesarean was both less costly and more effective than a trial of labor. Between 0.65 and 0.74, elective repeat cesarean was cost-effective (the cost-effectiveness ratio was less than $50,000 per quality-adjusted life-years), because, although it cost more than VBAC, it was offset by improved outcomes. Between 0.74 and 0.76, trial of labor was cost-effective. If the probability of successful vaginal delivery exceeded 0.76, trial of labor became less costly and more effective. Costs associated with a moderately morbid neonatal outcome, as well as the probabilities of infant morbidity occurring, heavily impacted our results.

CONCLUSION

The cost-effectiveness of VBAC depends on the likelihood of successful trial of labor. Our modeling suggests that a trial of labor is cost-effective if the probability of successful vaginal delivery is greater than 0.74. Improved algorithms are needed to more precisely estimate the likelihood that a patient with a previous cesarean will have a successful vaginal delivery.

New therapies for the pregnant patient with diabetes

Gestational diabetes complicates 3-5% of pregnancies. Of diabetes seen during pregnancy, 10% is pregestational and the remaining 90% represents gestational diabetes. (1,2) Pregnancy in women with pregestational diabetes is especially high risk. Spontaneous abortion, preterm labor, congenital malformations, preeclampsia, macrosomia, birth injury, and cesarean section are all increased in these pregnancies. Deterioration of maternal health during pregnancy, especially in the setting of diabetes-induced end-organ disease, is a real concern. Vigilant surveillance and management of associated disorders such as retinopathy, nephropathy, and chronic hypertension are required. During the preinsulin era, maternal and perinatal mortality in pregnancies complicated by pregestational diabetes was approximately 50%. (1,2) Although modern obstetrical management and the appropriate use of insulin have dramatically improved maternal-fetal outcomes, pregnant patient with diabetes remains at increased risk for complications. There is no doubt that optimizing maternal glucose control is a key element in avoiding established perinatal risks. The most effective means to accomplish this control are topics of active research. Further, hormonal changes during pregnancy can make glycemic control difficult even for the most compliant and educated patient. This paper discusses several new approaches, either currently in practice or under consideration, to pregnancies complicated by diabetes, including oral hypoglycemic agents, lispro, the insulin pump, and transplantation.

Ultrasonographic ear length measurement in normal second- and third-trimester fetuses

OBJECTIVE

We sought to develop a nomogram for fetal ear length measurements from a large population of healthy second- and third-trimester fetuses and to investigate the correlation of fetal ear length with other standard fetal biometry measurements, as follows: biparietal diameter, head circumference, abdominal circumference, femur length, and humerus length.

STUDY DESIGN

Ear length measurement was obtained prospectively in 4240 singleton fetuses between 15 and 40 weeks' gestational age. Either complete data for normal karyotype on amniocentesis or normal infant examination at birth or both were available in 2583 cases. These constituted the final study population.

RESULTS

A nomogram was developed by linearly regressing ear length on gestational age (Ear length [in millimeters] = 1.076 x Gestational age [in weeks] - 7. 308). There was a high correlation between ear length and gestational age (r = 0.96; P =.0001).

CONCLUSION

The results of this study provide normative data on growth of fetal ear length from 15 to 40 weeks' gestation. Good correlation was also observed between ear length and other fetal biometric measurements (biparietal diameter, head circumference, abdominal circumference, femur length, and humerus length).

Obstetric and gynecologic care of women with epilepsy

Optimal gynecologic and obstetric care for women with epilepsy requires a multidisciplinary approach throughout the various life stages. Epilepsy has important effects on puberty, contraceptive efficacy, pregnancy and fetal development, and menopause. This article discusses these effects and makes recommendations for gynecologic and obstetric care of patients with epilepsy, with particular focus on pregnancy. Despite very real risks to both the developing fetus and the mother, the majority of women with epilepsy--with appropriate pregnancy planning and management--have good pregnancy outcomes.

Randomized comparison of intravenous nitroglycerin and magnesium sulfate for treatment of preterm labor

OBJECTIVE

To compare the safety and efficacy of high-dose intravenous (IV) nitroglycerin with those of IV magnesium sulfate for acute tocolysis of preterm labor.

METHODS

Thirty-one women with preterm labor before 35 weeks' gestation were assigned randomly to IV magnesium sulfate or IV nitroglycerin for tocolysis. Preterm labor was defined as the occurrence of at least two contractions in 10 minutes, with cervical change or ruptured membranes. Acute tocolysis was defined as tocolysis for up to 48 hours. Magnesium sulfate was administered as a 4-g bolus, then at a rate of 2-4 g/h. Nitroglycerin was administered as a 100-microg bolus, then at a rate of 1- to 10-microg/kg/min. The primary outcome measure was achievement of at least 12 hours of successful tocolysis.

RESULTS

Thirty patients were available for analysis. There were no significant differences in gestational age, cervical dilation, or incidence of ruptured membranes between groups at the initiation of tocolysis. Successful tocolysis was achieved in six of 16 patients receiving nitroglycerin, compared with 11 of 14 receiving magnesium sulfate (37.5 versus 78.6%, P = .033). Tocolytic failures (nitroglycerin versus magnesium sulfate) were due to persistent contractions with cervical change or rupture of previously intact membranes (five of 16 versus two of 14), persistent hypotension (four of 16 versus none of 14), and other severe side effects (one of 16 versus one of 14). Maternal hemodynamic alterations were more pronounced in patients who received nitroglycerin, and 25% of patients assigned to nitroglycerin treatment had hypotension requiring discontinuation of therapy.

CONCLUSION

Tocolytic failures were more common with nitroglycerin than with magnesium sulfate. The hemodynamic alterations noted in patients receiving nitroglycerin, including a 25% incidence of persistent hypotension, might limit the usefulness of IV nitroglycerin for the acute tocolysis of preterm labor.

Diltiazem for maintenance tocolysis of preterm labor: comparison to nifedipine in a randomized trial

The objective of this study was to compare the safety and efficacy of maintenance tocolysis with oral diltiazem to oral nifedipine in achieving 37 weeks gestation. After successful intravenous tocolysis with magnesium sulfate, 69 women with preterm labor at <35 weeks gestation were randomly assigned to nifedipine (20 mg orally every 4-6 hr), or diltiazem (30-60 mg orally every 4-6 hr). The primary outcome was the percentage of patients achieving 37 weeks gestation. Maternal cardiovascular alterations and neonatal outcomes were also assessed. Sixty-nine patients were available for final analysis. Less patients on diltiazem as compared to nifedipine achieved 37 weeks (15.1% vs. 41.7%, P = 0.019). Gestational age at delivery was also less for patients receiving diltiazem (35.5 +/- 3.5 weeks vs. 33.4 +/- 3.9 weeks, P = 0.022). There were fewer days gained in utero from randomization to delivery with diltiazem as compared to nifedipine; however, this difference was not statistically significant (22.4 +/- 16.3 days vs. 31.2 +/- 24.4 days, P = 0.084). Maternal blood pressure and pulse during tocolysis did not differ significantly between groups. Despite the theoretical advantages of diltiazem tocolysis, maintenance tocolysis with diltiazem offered no benefit over nifedipine in achieving 37 weeks gestation. The cardiovascular alterations with either drug in normotensive, pregnant patients appear minimal.