Active management of risk in pregnancy at term in an urban population: an association between a higher induction of labor rate and a lower cesarean delivery rate

Differences in Determinants: Racialized Obstetric Care and Increases in U.S. State Labor Induction Rates

Induction of labor (IOL) rates in the United States have nearly tripled since 1990. We examine official U.S. birth records to document increases in states' IOL rates among pregnancies to Black, Latina, and White women. We test if the increases are associated with changes in demographic characteristics and risk factors among states' racial-ethnic childbearing populations. Among pregnancies to White women, increases in state IOL rates are strongly associated with changes in risk factors among White childbearing populations. However, the rising IOL rates among pregnancies to Black and Latina women are not due to changing factors in their own populations but are instead driven by changing factors among states' White childbearing populations. The results suggest systemic racism may be shaping U.S. obstetric care whereby care is not "centered at the margins" but is instead responsive to characteristics in states' White populations.

Induction of labor and risk of postpartum hemorrhage in low risk parturients

Objective

Labor induction is an increasingly common procedure, even among women at low risk, although evidence to assess its risks remains sparse. Our objective was to assess the association between induction of labor and postpartum hemorrhage (PPH) in low-risk parturients, globally and according to its indications and methods.

Method

Population-based case-control study of low-risk women who gave birth in 106 French maternity units between December 2004 and November 2006, including 4450 women with PPH, 1125 of them severe, and 1744 controls. Indications for labor induction were standard or non-standard, according to national guidelines. Induction methods were oxytocin or prostaglandins. Multilevel multivariable logistic regression modelling was used to test the independent association between induction and PPH, quantified as odds ratios.

Results

After adjustment for all potential confounders, labor induction was associated with a significantly higher risk of PPH (adjusted odds ratio, AOR1.22, 95%CI 1.04–1.42). This excess risk was found for induction with both oxytocin (AOR 1.52, 95%CI 1.19–1.93 for all and 1.57, 95%CI 1.11–2.20 for severe PPH) and prostaglandins (AOR 1.21, 95%CI 0.97–1.51 for all and 1.42, 95%CI 1.04–1.94 for severe PPH). Standard indicated induction was significantly associated with PPH (AOR1.28, 95%CI 1.06–1.55) while no significant association was found for non-standard indicated inductions.

Conclusion

Even in low risk women, induction of labor, regardless of the method used, is associated with a higher risk of PPH than spontaneous labor. However, there was no excess risk of PPH in women who underwent induction of labor for non-standard indications. This raises the hypothesis that the higher risk of PPH associated with labor induction may be limited to unfavorable obstetrical situations.

Effect of hyoscine butylbromide first stage of labour in multiparus women

BACKGROUND

Prolonged labor is one of the most important risk factors for perinatal compromise and, if caused by obstructed labor, it carries the risk of uterine rupture, postpartum hemorrhage (PPH), puerperal sepsis, and maternal death.

OBJECTIVE

To determine whether or not hyoscine butylbromide shortens the stages of labor, without an increase in maternal or neonatal complications.

METHOD

In single-blinded randomized clinical trial study, 188 multiparas women in active phase of labor who were admitted to Shahid Sadoughi Hospital from October 2006 to April 2007 in Yazd - Iran, were evaluated. They were divided hyoscine group (n = 94) received 20mg (1ml) of hyoscine and control group (n = 94) received 1 ml of normal saline was given as placebo, intravenously. The effects of hyoscine in shortening labor time; and neonatal Apgar score was compared.

RESULTS

Duration of the first (mean± SD: 186.8 ± 125.6 minutes vs. 260.4 ± 120.9 minutes, p= 0.00 1) and second stage of labor (mean± SD: 20.0 ± 8.1minutes vs. 25.8 ± 9.4 minutes, p= 0.03) was shorter in hyoscine group. Frequency of cesarean section and mean of neonatal Apgar score at minutes of one and 5 were not different in both groups. No serious adverse events were seen in the two groups.

CONCLUSION

Injection of hyoscine in active phase of labor can be effective in shortening of labor without any adverse effect on mother and fetus.

Maternal and neonatal outcomes following induction of labor: a cohort study

OBJECTIVE

To evaluate maternal and neonatal outcomes associated with birth at term by week of gestational age and also by onset of labor.

DESIGN

Cohort study.

SETTING

A state-wide perinatal outcome database.

POPULATION

28,626 women with spontaneous onset of labor, induction of labor for recognized indications and induction of labor for non-recognized indications.

METHODS

Cohort study utilizing a validated dataset comparing outcomes with type of onset of labor using a log binomial model.

MAIN OUTCOME MEASURES

Cesarean section, assisted vaginal birth, important measures of maternal and neonatal morbidity.

RESULTS

Induction of labor for non-recognized indications was associated with a significantly increased risk of a range of outcomes, including cesarean section (RR 1.67, 95% CI 1.55-1.80). The lowest risk of adverse maternal and infant outcome occurred with birth between 38 and 39 weeks and with the spontaneous onset of labor.

CONCLUSIONS

Induction of labor for non-recognized indications at term is associated with an increased risk of adverse outcomes. Caution is warranted with a liberal policy of induction of labor at term in an otherwise uncomplicated pregnancy.

National trends and racial differences in late preterm induction

OBJECTIVE

The objective of the study was to determine the trends and racial differences in late preterm induction (LPI) of labor in the United States.

STUDY DESIGN

Data from the National Vital Statistics System were used to identify women eligible for induction between 34 and 42 weeks' gestation from 1991 to 2006. Annual LPI rates were calculated, and maternal race/ethnicity was classified into 4 groups. Changes in the frequency and odds of LPI, stratified by race/ethnicity, were assessed using logistic regression.

RESULTS

Among the 42.0 million eligible women, LPI rates increased from 0.46% to 1.37% (P < .01) over 16 years. LPI rates were highest for black women (P < .01) each year, and after adjusting for confounding factors, the odds of LPI were highest (P < .01) and rose most rapidly (P < .01) for black women (non-Hispanic white: odds ratio [OR], 1 [referent]; Hispanic white: OR, 0.76; black: OR, 1.31; other: OR, 0.81; P < .01).

CONCLUSION

LPI rates were persistently highest and rose most rapidly for black women.

The influence of hospital type on induction of labor and mode of delivery

OBJECTIVE

The purpose of this study was to compare labor induction and cesarean delivery rates at term in community vs university hospitals.

STUDY DESIGN

A population-based retrospective cohort study of births was performed. Primary outcomes were term gestation at <39 weeks, labor induction, and cesarean delivery. After we adjusted for comorbidities, malpresentation, and previous cesarean delivery, logistic regression assessed the association between hospital type and primary outcomes.

RESULTS

Births occur less often in week 37 (n = 24390 [11%] vs 4006 [13%]; adjusted odds ratio [OR], 0.9; 95% confidence interval [CI], 0.8-0.9) and are similar in week 38 in community vs university hospitals. Inductions occur more commonly in community vs university settings at 37 weeks (n = 6440 [27%] vs 757 [19%]; adjusted OR, 1.7; 95% CI, 1.5-1.8) and at 38 weeks (n = 16586 [31%] vs 1530 [21%]; adjusted OR, 1.8; 95% CI, 1.7-1.9). Cesarean rates are no different between hospital types.

CONCLUSION

Induction is 70-80% more likely at community vs university hospitals before the optimal gestational age of ≥ 39 weeks, but cesarean delivery rates do not differ at term.

Trends in induction of labor at early-term gestation

OBJECTIVE

To determine the trends and racial differences in early-term induction of labor in the United States.

STUDY DESIGN

Data from the National Center for Health Statistics were used to identify women eligible for induction between 37-42 weeks' gestation in the United States from 1991-2006. Annual early-term induction rates were calculated, and maternal race/ethnicity was classified into 4 groups. The change in frequency and odds of early-term induction stratified by race/ethnicity over time was assessed.

RESULTS

Among 39.2 million eligible women, early-term induction rates increased from 2.0% to 8.0% (P < .01) over 16 years. Cross-sectional and annual early-term induction rates were highest for non-Hispanic white women during the study period (P < .01). After adjusting for confounding factors, the odds of any early-term induction were highest (P < .01) and rose most rapidly (P < .01) among non-Hispanic white women compared with women from other racial/ethnic groups.

CONCLUSION

In the United States, early-term induction rates rose significantly and were highest among non-Hispanic white women.

Late pregnancy complications can affect risk estimates of elective induction of labor

OBJECTIVE

Multiple observational studies have emphasized the increased risk of elective induction versus spontaneous labor. We estimated the risks of elective induction before 39 weeks compared to expectant management.

METHODS

Using a single institution's delivery data (1996-2004), we identified women with uncomplicated term gestations who underwent elective induction before 39 weeks (Early Induction Group). A comparison group of women eligible for elective induction before 39 weeks but who were managed expectantly was created by identifying the remaining deliveries ≥ 39 weeks and excluding women with "established" pregnancy complications such as diabetes or heart disease (Expectant Management Group), but retaining women with complications that may have developed while waiting, e.g. gestational hypertension or abruption.

RESULTS

Pregnancies in the Early Induction Group were generally not at increased risk for morbidity when compared to the entire Expectant Management Group, in whom 49% developed pregnancy complications or went postdates. These pregnancies had poorer maternal and neonatal outcomes when compared to patients who remained uncomplicated with spontaneous labor onset, thus reducing the overall benefit of expectant management.

CONCLUSIONS

Failure to account for the large proportion of women who develop late pregnancy complications can falsely elevate the estimated risk of elective induction prior to 39 weeks.

Risk adjustment in maternity care: the use of indirect standardization

PURPOSE

Annual US national rates of family physicians providing maternity care are decreasing and rates of cesarean delivery are increasing. Family physicians tend to have lower cesarean delivery rates than obstetrician specialists, but this association is usually explained by an assumed lower pre-delivery risk for cesarean delivery. This study was developed to compare the estimated risk of cesarean delivery in patients of the two specialties.

METHODS

A retrospective cohort study within an urban teaching hospital compared 100 family- physician treated subjects to 300 subjects treated by obstetrician-specialists. Risk factors for cesarean delivery were identified, and an indirect standardization procedure was used to compare the pre-38 week of gestation risk of cesarean delivery in the two groups.

RESULTS

The patients treated by family physicians had a projected pre-38 week of gestation risk of cesarean delivery (17.4%) that was similar to the actual rate of cesarean delivery in the obstetrician-specialist group (16.7%). The Standardized Cesarean Delivery Ratio was 1.04.

CONCLUSION

Lower cesarean delivery rates provided by family physicians may not be simply due to case-mix issues. Additional studies comparing the pre-delivery estimation of cesarean delivery risk would be helpful in measuring the relative levels of obstetric risk of patients treated by different maternity-care provider types.

The association between increased use of labor induction and reduced rate of cesarean delivery

AIM

An association was recently reported between a low cesarean section delivery rate and a method of obstetrical care that involved the frequent use of risk-guided prostaglandin-assisted preventive labor induction. We sought to confirm this finding in a subsequent group of pregnant women.

METHODS

A retrospective cohort study design was used to compare the outcomes of 100 consecutively delivered women, who were exposed to the alternative method of care, with the outcomes of 300 randomly chosen women who received standard management. The primary outcome was group cesarean delivery rate. Secondary outcomes were rates of neonatal intensive care unit admission, low 1-minute Apgar score, low 5-minute Apgar score, and major perineal trauma.

RESULTS

Women exposed to the alternative method of obstetrical care had a higher induction rate (59% vs. 16.3%, p < 0.001), a more frequent use of prostaglandins for cervical ripening (32% vs. 13%, p < 0.001), and a lower cesarean delivery rate (7% vs. 20.3%, p = 0.002). Exposed women did not experience higher rates of other adverse birth outcomes.

CONCLUSIONS

Exposure to an alternative method of obstetrical care that used high levels of risk-driven prostaglandin-assisted labor was again associated with two findings: a lower group cesarean delivery rate and no increases in levels of other adverse birth outcomes. An adequately powered randomized controlled trial is needed to further explore this alternative method of care.

The active management of impending cephalopelvic disproportion in nulliparous women at term: a case series

Background. The Active Management of Risk in Pregnancy at Term (AMOR-IPAT) protocol has been associated in several studies with significant reductions of group cesarean delivery rate. Present within each of these studies were nulliparous women with risk factors for cephalopelvic disproportion. Risk factors for cephalopelvic disproportion in nulliparous women are especially important because they represent the precursors for the most common indication for primary cesarean delivery. Cases. Three examples of exposure of urban nulliparous women to the AMOR-IPAT protocol are presented. Each woman's risk factor profile for Cephalopelvic Disproportion (CPD) was used to estimate her Upper Limit of Optimal Time of Vaginal Delivery for CPD (UL-OTDcpd). Labor management and clinical outcomes for each case are presented. A simple table summarizing induction rates and birth outcome rates of exposed versus nonexposed nulliparous women is also presented. Conclusion. Because the mode of delivery of the first birth substantially impacts birth options in later pregnancies, the impact of AMOR-IPAT on nulliparous patients is particularly important. Determining the UL-OTDcpd in nulliparous patients, and carefully inducing each patient who has not entered labor by her UL-OTDcpd, may be an effective way of lowering rates of cesarean delivery in nulliparous women.

Active management of risk in nulliparous pregnancy at term: association between a higher preventive labor induction rate and improved birth outcomes

OBJECTIVE

The objective of the study was to determine whether exposure of nulliparous women to a high rate of preventive labor induction was associated with improvement in birth health.

STUDY DESIGN

A risk-scoring system was used to guide the frequent use of preventive labor induction in 100 nulliparous women. The birth outcomes of this group were compared with those of 352 nulliparous women who received usual care. Cesarean delivery was the primary study outcome. The Adverse Outcome Index and the rate of uncomplicated vaginal delivery were used to measure overall birth health.

RESULTS

The exposed group experienced a higher labor induction rate (48% vs 23.6%; P < .001), a lower cesarean rate (9% vs 25.8%; adjusted odds ratio, 0.36; P = .02), and better composite birth outcomes.

CONCLUSION

Exposure of nulliparous women to a high preventive induction rate was significantly associated with improvement in birth health. Prospective randomized trials are needed to further explore the utility of risk-guided preventive labor induction.

The active management of risk in multiparous pregnancy at term: association between a higher preventive labor induction rate and improved birth outcomes

OBJECTIVE

To determine whether exposure of multiparous women to a high rate of preventive labor induction was associated with a significantly lower cesarean delivery rate.

STUDY DESIGN

Retrospective cohort study involving 123 multiparous women, who were exposed to the frequent use of preventive labor induction, and 304 multiparous women, who received standard management. Rates of cesarean delivery and other adverse birth outcomes were compared in the 2 groups. Logistic regression controlled for confounding covariates.

RESULTS

The exposed group had a lower cesarean delivery rate (adjusted odds ratio, 0.09; 0.8% vs 9.9%; P = .02) and a higher uncomplicated vaginal delivery rate (odds ratio, 0.53; 78.9% vs 66.4%; P = .01). Exposure was not associated with higher rates of other adverse birth outcomes.

CONCLUSION

Exposure of multiparous women to a high rate of preventive labor induction was significantly associated with improved birth outcomes, including a very low cesarean delivery rate. A prospective randomized trial is needed to determine causality.

Preventive labor induction-AMOR-IPAT: much promise, not yet realized

"Preventive Labor Induction-AMOR-IPAT" is a method designed to time induction before the fetus becomes too large or the placenta dysfunctional. In two retrospective cohort studies and one randomized trial, the developers claim to have reduced cesarean section rates and improved newborn outcomes. These claims have yet to be substantiated in an adequately powered trial, but having decided on the need for an induction, the investigators do manage inductions in a woman-centered and intimate style that has merit.

Postterm pregnancy: how can we improve outcomes?

Postterm pregnancy is defined as one which has progressed to 42 0/7 weeks or beyond. The most common reason to be diagnosed with a postterm pregnancy is inaccurate pregnancy dating, but it is also associated with obesity, nulliparity, and a prior history of postterm pregnancy. The rate of postterm pregnancy appears to be decreasing whether due to improved pregnancy dating or an increase in induction of labor. Postterm pregnancy is associated with both maternal and neonatal morbidity and fetal and neonatal mortality; similarly pregnancies beyond 41 weeks' gestation are associated with increases in these perinatal complications. Prevention of postterm pregnancies may include stripping or sweeping the membranes and unprotected coitus. Management of such pregnancies may include induction of labor and fetal antenatal monitoring. Individual patient management should involve careful counseling regarding the risks and benefits of each of the components of care.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this article, the reader should be able to recall the increasing risks of poor outcomes associated with prolonged pregnancy, demonstrate knowledge regarding gestational dating and use of cervical ripening agents in their care of pregnant women, and use evidence-based information when counseling their term patients regarding postterm pregnancy management.

New indications for antepartum testing: making the case for antepartum surveillance or timed delivery for women of advanced maternal age

Maternal age is an independent risk factor for stillbirth; a moderate number of these occur in normally formed babies near term. For a woman 40 years of age or older giving birth, her risk of having a chromosomal anomaly is 1/66. What is not appreciated is that even without medical risk factors, her risk of having a stillbirth after 37 weeks of gestation is 1/116. This article reviews the risks and benefits of the strategy of antepartum testing and timed delivery and discusses the limitations of the available data in this field.

Management of decreased fetal movements

Maternal perception of decreased fetal activity is a common complaint, and one of the most frequent causes of unplanned visits in pregnancy. No proposed definitions of decreased fetal movements have ever been proven to be superior to a subjective maternal perception in terms of identifying a population at risk. Women presenting with decreased fetal movements do have higher risk of stillbirth, fetal growth restriction, fetal distress, preterm birth, and other associated outcomes. Yet, little research has been conducted to identify optimal management, and no randomized controlled trials have been performed. The strong associations with adverse outcome suggest that adequate management should include the exclusion of both acute and chronic conditions associated with decreased fetal movements. We propose guidelines for management of decreased fetal movements that include both a nonstress test and an ultrasound scan and report findings in 3014 cases of decreased fetal movements.

The impact of the active management of risk in pregnancy at term on birth outcomes: a randomized clinical trial

OBJECTIVE

The purpose of this study was to compare birth outcomes that result from the active management of risk in pregnancy at term (AMOR-IPAT) to those outcomes that result from standard management.

STUDY DESIGN

This was a randomized clinical trial with 270 women of mixed parity. AMOR-IPAT used preventive labor induction to ensure delivery before the end of an estimated optimal time of delivery. Rates of 4 adverse obstetric events and 2 composite measures were used to evaluate birth outcomes.

RESULTS

The AMOR-IPAT-exposed group had a similar cesarean delivery rate (10.3% vs 14.9%; P = .25), but a lower neonatal intensive care unit admission rate (1.5% vs 6.7%; P = .03), a higher uncomplicated vaginal birth rate (73.5% vs 62.8%; P = .046), and a lower mean Adverse Outcome Index score (1.4 vs 8.6; P = .03).

CONCLUSION

AMOR-IPAT exposure improved the pattern of birth outcomes. Larger randomized clinical trials are needed to explore further the impact of AMOR-IPAT on birth outcomes and to determine the best methods of preventive labor induction.

Measuring perinatal complications: methodologic issues related to gestational age

BACKGROUND

Perinatal outcomes differ by week of gestational age. However, it appears that how measures to examine these outcomes vary among various studies. The current paper explores how perinatal complications are reported and how they might differ when different denominators, numerators, and comparison groups are utilized.

CONCLUSION

One issue that can clearly affect absolute rates and trends is how groups of women are categorized by their gestational age. Since most perinatal outcomes can only occur in women and neonates who have delivered, using the number of pregnancies delivered (PD) as the denominator of outcomes is appropriate. However, for an outcome such as antepartum stillbirth, all women who are pregnant at a particular gestational age are at risk. Thus, the denominator should include all ongoing pregnancies (OP). When gestational age is used by week this means using both deliveries during a particular week plus those women who deliver beyond the particular week of gestation in the denominator. Researchers should be careful to make sure they are utilizing the appropriate measure of perinatal complications so they do not report findings that would be misleading to clinicians, patients, and policy makers.

Induction of labor in the absence of standard medical indications: incidence and correlates

BACKGROUND

Induction of labor is an increasingly common obstetrical procedure, with approximately 20-34% of women undergoing labor induction in the United States annually.

OBJECTIVE

To determine the extent of labor induction in the absence of standard medical indications and to assess possible associations with maternal and infant characteristics and hospital factors.

METHODS

We ascertained induction of labor and associated details as part of a medical record validation study of 4541 women with live, singleton births in 2000 in Washington State using medical record, birth certificate, and hospital discharge data. In this analysis, we report findings for the 1473 women (33% of original cohort) whose medical records indicated that their labors were induced.

RESULTS

Among women with induced labor, 7.9% had no clinical information providing an indication for the induction, and 6.4% had only "nonstandard" indications recorded. Compared with women delivering in moderate volume hospitals, women who delivered at lower volume (odds ratios [OR] 3.9; 95% confidence intervals [CI] 1.8-8.6) or higher volume hospitals (OR 4.2; 95% CI 2.4-7.2) had significantly increased risk for undocumented indication of labor. Women who had undocumented indication for induction were at significantly decreased risk of giving birth at a teaching hospital and a public nonfederally owned hospital, and were at greater risk to give birth at a private religious hospital. Factors that remained independently associated with nonstandard indication for induction of labor were primiparas (OR 2.4; 95% CI 1.3-4.2); multiparas (OR 4.3; 95% CI 2.5-7.4), pregnancy-induced hypertension (OR 0.2; 95% CI 0.1-0.4), hospital volume >or=2000 births annually (OR 19.9; 95% CI 6.7-58.6), primary (OR 11.7; 95% CI 4.1-33.6), and tertiary level hospital (OR 0.4; 95% CI 0.2-0.7).

CONCLUSIONS

Our findings suggest that nearly 15% of inductions either were not clinically indicated according to standard protocols or indications were incompletely documented. At minimum, further studies are needed to explore how best to improve documentation of indications of labor because accurately describing, among other things, the process of labor induction, is a basic benchmark of care.

A preventive approach to obstetric care in a rural hospital: association between higher rates of preventive labor induction and lower rates of cesarean delivery

PURPOSE

Annual cesarean delivery rates in North America are increasing. Despite the morbidity associated with cesarean delivery, a safe preventive strategy to reduce the use of this procedure has not been forthcoming. During the 1990s, clinicians in a rural hospital developed a method of care involving prostaglandin-assisted preventive labor induction. An inverse relationship was noted between yearly hospital rates of labor induction and cesarean delivery. The purpose of our study was to compare cesarean delivery rates between practitioners who often used preventive induction and practitioners who did not, while controlling for patient mix and differences in practice style.

METHODS

Between 1993 and 1997, different hospital practitioners used risk-guided prostaglandin-assisted preventive labor induction with differing intensity. We used a retrospective cohort design, based on the practitioner providing prenatal care, to compare birth outcomes in women exposed to this alternative method of care with those in women not exposed. Multiple logistic regression analysis controlled for patient characteristics and clustering by practitioner.

RESULTS

The exposed group (n = 794), as compared with the nonexposed group (n = 1,075), had a higher labor induction rate (31.4% vs 20.4%, P <.001), a greater use of prostaglandin E2 (23.3% vs 15.7%, P <.001), and a lower cesarean delivery rate (5.3% vs 11.8%, P <.001). Adjustment for cluster effects, patient characteristics, and the use of epidural analgesia did not eliminate the significant association between exposure to this preventive method of care and a lower cesarean delivery rate. Rates of other adverse birth outcomes were either unchanged or reduced in the exposed group.

CONCLUSIONS

A preventive approach to reducing cesarean deliveries may be possible. This study found that practitioners who often used risk-guided, prostaglandin-assisted labor induction had a lower cesarean delivery rate without increases in rates of other adverse birth outcomes. Randomized controlled trials of this method of care are warranted.

Prolonged Pregnancy:

The timely onset of labor and birth is an important determinant of perinatal outcome. Prolonged (postterm) pregnancy--defined as delivery at or beyond 42 weeks' gestation--complicates 10% of all gestations and is associated with increased risks to both fetus (stillbirth, macrosomia, birth injury, meconium aspiration syndrome) and mother (cesarean delivery, severe perineal injury, postpartum hemorrhage). The risk of routine induction of labor (failed induction leading to cesarean delivery) in the era of cervical ripening is lower than previously reported. For these reasons, the authors favor a policy of routine induction of labor for low-risk pregnancies at 41 weeks' gestation.

Maternal morbidity associated with cesarean delivery without labor compared with induction of labor at term

OBJECTIVE

To estimate the maternal morbidity associated with cesarean deliveries performed at term without labor compared with morbidity associated with induction of labor at term.

METHODS

A 15-year population-based cohort study (1988-2002) using the Nova Scotia Atlee Perinatal Database compared maternal outcomes in nulliparous women delivering by cesarean delivery without labor and nulliparous women at term undergoing induction of labor for planned vaginal delivery with singleton, cephalic presentation.

RESULTS

A total of 5,779 pregnancies satisfied inclusion and exclusion criteria, 879 of which were cesarean deliveries without labor. There were no maternal deaths. There was no difference in wound infection, puerperal febrile morbidity, blood transfusion or intraoperative trauma. After controlling for potential confounders, women undergoing cesarean delivery without labor were less likely to have complications of early postpartum hemorrhage (relative risk 0.61, 95% confidence interval 0.42-0.88, number needed to treat 32) and composite maternal morbidity (relative risk 0.71, 95% confidence interval 0.52-0.95, number needed to treat 34) compared with women undergoing induction of labor. Subgroup analyses of maternal outcomes after induction of labor in women by method of delivery were also performed and demonstrated additional risks of traumatic morbidity after induction of labor. The highest morbidity was found in the assisted vaginal delivery and cesarean delivery in labor groups.

CONCLUSION

Early postpartum hemorrhage and composite maternal morbidity were decreased in cesarean delivery without labor compared with induction of labor. Hemorrhagic and traumatic morbidities with labor induction are increased after assisted vaginal delivery and cesarean delivery in labor compared with cesarean delivery without labor.

Maternal complications of pregnancy increase beyond 40 weeks of gestation in low-risk women

OBJECTIVE

We sought to determine when rates of maternal pregnancy complications increase for low-risk nulliparous and multiparous women at term.

METHODS

We designed a retrospective cohort study of low-risk women delivered beyond 37 weeks gestational age from 1976 to 2001. Rates of mode of delivery and maternal complications of labor and delivery were examined by gestational age with both bivariate and multivariate analyses. Statistical significance was designated by P<0.05.

RESULTS

We found that among the 32,828 low-risk women who delivered at 37 completed weeks and beyond, the rates of primary cesarean delivery, operative vaginal delivery, third- or fourth-degree perineal lacerations, and chorioamnionitis all increased at 40 weeks of gestation (P<0.001), and the rate of postpartum hemorrhage increased at 41 weeks of gestation (P<0.001). These increases of rates of complications were larger and increased at an earlier gestational age among nulliparous women.

CONCLUSION

We found that the risk of maternal complications for otherwise low risk nulliparous and multiparous women increased as pregnancy progressed beyond 40 weeks of gestation. Counseling of women who progress past their EDC should include comparing the risks of induction of labor to that of expectant management.

Induction of labor and cesarean delivery by gestational age

OBJECTIVE

Studies of cesarean delivery (CD) rates among women undergoing induction of labor (IOL) often compare such women to women experiencing spontaneous labor at similar gestational ages. We sought to examine the association between IOL at various gestational ages and CD, accounting for the effect of increased gestational age among the comparison group who were managed expectantly.

STUDY DESIGN

We conducted a retrospective cohort study of all term, singleton, cephalic presentation pregnancies delivered at our institution over 15 years excluding cesarean deliveries before labor. For each gestational age of induction, we created a comparison group of women who were undelivered at that gestational age, and who experienced labor at some future gestational age.

RESULTS

In women undergoing IOL at 38 weeks gestation, the CD rate was 11.9% as compared to 13.3% (P = .42) of women beyond 38 weeks gestation. The CD rate for induction of labor compared to ongoing pregnancy was 14.3% versus 15.0% (P = .62) at 39 weeks, 20.4% versus 19.0% (P = .41) at 40 weeks, and 24.3% versus 26.0% (P = .39) at 41 weeks. When controlling for potential confounding, there was a higher rate of CD among women with expectant management beyond 38 weeks (adjusted odds ratio [AOR] 1.80; 95% CI 1.29-2.53), 39 weeks (1.39; 95% CI 1.08-1.80), and 40 weeks (AOR 1.27; 95% CI 1.00-1.62).

CONCLUSION

Our findings suggest that IOL may not increase a woman's risk of CD when compared to expectant management. While this question has been addressed prospectively at 41 weeks gestation, it requires further examination at earlier gestations and among various subgroups.

The impact of the interaction between increasing gestational age and obstetrical risk on birth outcomes: evidence of a varying optimal time of delivery

OBJECTIVE

To estimate the gestational age ranges that result in optimal birth outcomes for each of four risk-defined groups.

STUDY DESIGN

Retrospective cohort study of singleton late third-trimester deliveries at a large urban teaching hospital between July 1995 and September 2003. Low-risk, advanced maternal age, hypertensive and diabetic patients were identified and grouped. Rates, by day of gestation at delivery, of cesarean delivery, major maternal perineal trauma, low 5-min APGAR score and NICU admission were determined for each study group.

RESULTS

Each study group had meaningful changes in rates of obstetric outcomes as a function of gestational age at delivery and these patterns differed from group to group. A unique optimal time of delivery (OTD) was estimated for each group. The low-risk group OTD was calculated to be 37 weeks 1 day to 41 weeks 0 day; the advanced maternal age group OTD was 38 weeks 5 days to 39 weeks 6 days; the hypertension group OTD was 39 weeks 2 days to 40 weeks 1 day; and the diabetes mellitus group OTD was 40 weeks 3 days to 41 weeks 1 day.

CONCLUSIONS

The OTD varied based on obstetrical risk. Strategies to increase the proportion of deliveries that occur within the OTD for specific risk-defined groups could theoretically improve birth outcomes.

Changes in the gestational age distribution among U.S. singleton births: impact on rates of late preterm birth, 1992 to 2002

There is mounting evidence that infants born late preterm (34-36 weeks) are at greater risk for morbidity than term infants. This article examines the changing epidemiology of gestational length among singleton births in the United States, from 1992 to 2002. Analyzing gestational age by mode of delivery, the distribution of spontaneous births shifted to the left, with 39 weeks becoming the most common length of gestation in 2002, compared with 40 weeks in 1992 (P < 0.001). Deliveries at > or =40 weeks gestation markedly decreased, accompanied by an increase in those at 34 to 39 weeks (P < 0.001). Singleton births with PROM or medical interventions had similar trends. Changes in the distribution of all singleton births differed by race/ethnicity, with non-Hispanic white infants having the largest increase in late preterm births. These observations, in addition to emerging evidence of increased morbidity, suggest the need for investigation of optimal obstetric and neonatal management of these late preterm infants.