The effect of placenta previa on neonatal mortality: a population-based study in the United States, 1989 through 1997

OBJECTIVE: The purpose of the study was to explore the associations of placenta previa with preterm delivery, growth restriction, and neonatal survival. STUDY DESIGN: A retrospective cohort study was performed of live births in the United States (1989-1991 and 1995-1997) that used the national linked birth/infant death records from 22,368,235 singleton pregnancies. The diagnosis of previa was restricted to those live births that were delivered (> or =24 weeks) by cesarean delivery. We evaluated gestational age and birth weight-specific risk of neonatal deaths (within the first 28 days) in relation to placenta previa. Fetal growth was assessed in centiles of birth weight (<3rd, 3rd-4th, 5th-9th, 10th-90th, and >90th centile), adjusted for gestational age. All analyses were adjusted for the confounding effects of the year of delivery, maternal age, gravidity, education, prenatal care, marital status, and race/ethnicity. RESULTS: Placenta previa was recorded in 2.8 per 1000 live births (n = 61,711). Neonatal mortality rate was 10.7 with previa, compared with 2.5 per 1,000 among other pregnancies (relative risk, 4.3; 95% confidence interval, 4.0,4.8). At 28 to 36 weeks, babies born to women with placenta previa weighed, on average, 210 g lower than babies born to women without placenta previa (P <.001). Compared with babies born to women without previa, the risk of death from placenta previa was lower among preterm babies (<37 weeks of gestation), with a crossover at 37 weeks where the mortality rate was higher for babies born to women with placenta previa than for babies born to women without placenta previa. This crossover also persisted in an analysis by birth weight and term births (delivered at > or =37 weeks of gestation). Mortality rates for term births were higher among babies born to women with placenta previa than among babies born women without placenta previa who were at the 10th to 90th centile (relative risk, 1.9; 95% confidence interval, 1.3, 2.8), and those at >90th centile (relative risk, 3.6; 95% confidence interval, 1.3, 9.6). Among preterm births, however, placenta previa was not associated with increased neonatal mortality by fetal growth centiles. CONCLUSION: The risk of neonatal mortality was higher for babies born to women with placenta previa than for babies born to women without placenta previa who were delivered at > or =37 weeks of gestation. Pregnancies that are diagnosed with placenta previa must be monitored carefully, especially as they approach term.     

The impact of prenatal care on neonatal deaths in the presence and absence of antenatal high-risk conditions

OBJECTIVE: The purpose of this study was to determine the association between prenatal care in the United States and the neonatal death rate in the presence and absence of antenatal high-risk conditions. STUDY DESIGN: Data were derived from the national perinatal mortality data sets for the years 1995 through 1997, which were provided by the National Center for Health Statistics. Analyses were restricted to singleton live births that occurred after 23 completed weeks of gestation. Multivariable logistic regression analyses were used to adjust for the presence or absence of various antenatal high-risk conditions, maternal age, gestational age at delivery, and birth weight. RESULTS: Of 10,530,608 singleton live births, 18,339 (1.7/1000 births) resulted in neonatal death. Neonatal death rates (per 1000 live births) were higher for African American infants compared with white infants in the presence (2.7 vs 1.5, respectively) and absence (10.7 vs 7.9, respectively) of prenatal care. Lack of prenatal care was associated with an increase in neonatal deaths, which was greater for infants born at > or =36 weeks of gestation (relative risk, 2.1; 95% CI, 1.8, 2.4). Lack of prenatal care was also associated with increased neonatal death rates in the presence of preterm premature rupture of the membranes (relative risk, 1.3; 95% CI, 1.1, 1.5), placenta previa (relative risk, 1.9; 95% CI, 1.2, 2.9), fetal growth restriction (relative risk, 1.7; 95% CI, 1.2, 1.6), and postterm pregnancy (relative risk, 1.4; 95% CI, 1.0, 2.9). CONCLUSION: In the United States, prenatal care is associated with fewer neonatal deaths in black and white infants. This beneficial effect was more pronounced for births that occurred at > or =36 weeks of gestation and in the presence of preterm premature rupture of the membranes, placenta previa, fetal growth restriction, and postterm pregnancy.     

Placenta previa in singleton and twin births in the United States, 1989 through 1998: a comparison of risk factor profiles and associated conditions

OBJECTIVE: The purpose of this study was to compare risk factor profiles for placenta previa between singleton and twin live births. STUDY DESIGN: This cohort study was based on United States natality data files (1989 through 1998) and comprised 37,956,020 singleton births and 961,578 twin births. Women who were diagnosed with placenta previa were included only if they were delivered by cesarean delivery. Risk factors for placenta previa that were examined included sociodemographic (age, gravidity, education, marital status, and race), behavioral (prenatal care, smoking, and alcohol use), previous preterm birth, and medical and obstetric factors. Effect modification between maternal age and gravidity and the dose-response relationship with number of cigarettes smoked/day on placenta previa risk were also evaluated. RESULTS: The rate of placenta previa was 40% higher among twin births (3.9 per 1,000 live births, n = 3,793 births) than among singleton births (2.8 per 1,000 live births, n = 104,754 births). Comparison of risk factors for placenta previa between the singleton and twin births revealed fairly similar risk factor profiles. Compared with primigravid women <20 years old, the risk for placenta previa increased by advancing age and by increasing number of pregnancies among both singleton and twin births. The number of cigarettes smoked per day also showed a dose-response trend for placenta previa risk in the two groups. CONCLUSION: The increased rate of placenta previa among twin births underscores the need to monitor carefully such pregnancies with heightened suspicion and awareness for the development of this condition.     

Placenta previa and the risk of preterm delivery.

OBJECTIVES: We aimed to quantify the risk of preterm delivery and maternal and neonatal morbidities associated with placenta previa. STUDY DESIGN: We conducted a retrospective cohort study of singleton births that occurred between 1976 and 2001, examining outcomes including preterm delivery and perinatal complications. Multivariate logistic regression was used to control for potential confounders. Kaplan-Meier survival curves were constructed to compare preterm delivery in pregnancies complicated by previa vs. no previa. RESULTS: Among the 38 540 women, 230 women had previas (0.6%). Compared to controls, pregnancies with previa were significantly associated with preterm delivery prior to 28 weeks (3.5% vs. 1.3%; p = 0.003), 32 weeks (11.7% vs. 2.5%; p < 0.001), and 34 weeks (16.1% vs. 3.0%; p < 0.001) of gestation. Patients with previa were more likely to be diagnosed with postpartum hemorrhage (59.7% vs. 17.3%; p < 0.001) and to receive a blood transfusion (11.8% vs. 1.1%; p < 0.001). Survival curves demonstrate the risk of preterm delivery at each week and showed an overall higher rate of preterm delivery for patients with a placenta previa. CONCLUSIONS: Placenta previa is associated with maternal and neonatal complications, including preterm delivery and postpartum hemorrhage. These specific outcomes can be used to counsel women with previa.     

Trends in twin neonatal mortality rates in the United States, 1989 through 1999: influence of birth registration and obstetric intervention

OBJECTIVE: We sought to evaluate the contributions of changes in birth registration, labor induction, and cesarean delivery on trends in twin neonatal mortality rates. STUDY DESIGN: We conducted a population-based, retrospective cohort study of twin live births, using linked birth-infant death data in the United States (1989-1999). Relative risks and 95% confidence intervals that quantified changes in neonatal (0-27 days) mortality rates were derived from ecologic logistic regression models that were fit after aggregation of the data by each state in the United States. RESULTS: The frequency of live born twins who weighed <500 g increased 72%, from 0.7% in 1989 to 1.2% in 1999, of live born twins who weighed 500 to 749 g and 750 to 999 g increased by 55% and 28%, respectively, between 1989 and 1999. Preterm birth rates increased by 19%, from 46.2% in 1989 to 57.2% in 1999. The rate of labor induction increased from 5.8% to 13.9%, and the cesarean delivery rate increased from 49.8% to 56.3%. Between 1989 to 1991 and 1997 to 1999, the crude neonatal mortality rates among twins who weighed >or=500 g declined by 37% (95% CI, 35%-40%) from 21.5 to 13.6 per 1000 twin live births. Adjustments for preterm labor induction, preterm cesarean delivery, term labor induction, term cesarean delivery, and sociodemographic factors had little influence on neonatal mortality rate trends. CONCLUSION: Increases in preterm birth because of obstetric intervention among twins have not led to increases in twin neonatal mortality rates in the United States.     

Stillbirths and neonatal deaths in appropriate, small and large birthweight for gestational age fetuses

AIMS: To compare the risk of stillbirth and neonatal death in small-for-gestational-age (SGA), appropriate-for-gestational-age (AGA) and large-for-gestational-age (LGA) fetuses and neonates. DESIGN: Retrospective analysis of 662 043 births and outcomes recorded in the Victorian Perinatal Data Collection Unit (1992-2002). INCLUSION CRITERIA: Births in Victoria in 1992-2002. EXCLUSION CRITERIA: Multiple pregnancy and congenital birth defects. MAIN OUTCOME MEASURES: Births, stillbirths and neonatal deaths at each week of gestation after 23 weeks were stratified by birthweight into appropriate, small and large for gestational age. Stillbirth risk per 1000 ongoing pregnancies and neonatal death rate per 1000 live births were calculated. RESULTS: For the AGA group, the overall stillbirth risk was 2.88 per 1000 and neonatal death rate was 1.35 per 1000. In the LGA group, these were 2.62 and 1.83 per 1000, respectively. The slight increase in neonatal death rate among LGA fetuses was confined to those delivered after 28 weeks gestation. In the SGA group, the stillbirth risk and neonatal death rate were 15.1 and 3.99 per 1000, respectively. CONCLUSION: The risk of stillbirth per week of gestational age and neonatal death rates do not differ significantly between AGA and LGA fetuses and neonates. The SGA fetus is at significantly greater risk of both stillbirth and neonatal death, particularly with advancing gestational age.     

Neonatal outcomes with placenta previa

OBJECTIVE: To identify neonatal complications associated with placenta previa. METHODS: This was a population-based, retrospective cohort study involving all singleton deliveries in Nova Scotia from 1988 to 1995. The study group consisted of all completed singleton pregnancies complicated by placenta previa; all other singleton pregnancies were considered controls. Patient information was collected from the Nova Scotia Atlee perinatal database. Neonatal complications were evaluated while controlling for potential confounders. The data were analyzed using chi2, Fisher exact test, and multiple logistic regression. RESULTS: Among 92,983 pregnancies delivered during the study period, 305 cases of placenta previa were identified (0.33%). After controlling for potential confounders, neonatal complications significantly associated with placenta previa included major congenital anomalies (odds ratio [OR] 2.48), respiratory distress syndrome (OR 4.94), and anemia (OR 2.65). The perinatal mortality rate associated with placenta previa was 2.30% (compared with 0.78% in controls) and was explained by gestational age at delivery, occurrence of congenital anomalies, and maternal age. Although there was a higher rate of preterm births in the placenta previa group (46.56% versus 7.27%), there was no difference in birth weights between groups after controlling for gestational age at delivery. CONCLUSION: Neonatal complications of placenta previa included preterm birth, congenital anomalies, respiratory distress syndrome, and anemia. There was no increased occurrence of fetal growth restriction.     

Is tocolysis safe in the management of third-trimester bleeding?

Objective: Expectant management is among the current treatment options for pregnancies complicated by third-trimester bleeding at <36 weeks’ gestation. The use of tocolytic agents to stop associated contractions is still somewhat controversial, however, and the number of cases reported to date is small. The purpose of our study was to find a large number of cases of preterm third-trimester bleeding that was treated with tocolytic agents and evaluate them for any evidence of potential harm related to the use of these agents. Study Design: Every case of third-trimester bleeding for a 6-year period was obtained from a perinatal database that was created as patients were hospitalized. Only cases of patients with onset of bleeding between 23 and 36 weeks’ gestation were analyzed. Data collected included the gestational age at the time of first bleeding, the gestational age at delivery, whether tocolytic agents were used, the need for transfusion, maternal morbidity, and neonatal outcome. Results: A total of 236 cases, consisting of 131 cases of abruptio placentae and 105 cases of placenta previa, met the study criteria. In the abruptio placentae group 95 women (73%) were treated with tocolytic agents. In this group the mean gestational age at the time of first bleeding was 28.9 weeks, the mean time from bleeding until delivery was 18.9 days, the median time from bleeding until delivery was 7 days, and the neonatal mortality rate was 51 deaths/1000 live births. In the placenta previa group 76 patients (72%) were treated with tocolytic agents. In this group the mean gestational age at first bleeding was 29.5 weeks, the mean time from bleeding until delivery was 29.3 days, the median time from bleeding until delivery was 22 days, and the neonatal mortality rate was 39 deaths/1000 live births. In both groups the need for transfusion and the incidence of fetal distress were not increased by the use of tocolytic agents. Among the 171 combined patients who underwent tocolysis, no maternal morbidity related to the tocolytic agents was found and no stillbirths occurred after admission. The neonatal deaths were all related to complications of prematurity. Conclusions: This is the largest series to date evaluating the use of tocolytic agents in preterm patients with third-trimester bleeding. From these data there does not appear to be any increased morbidity or mortality associated with tocolytic agent use in a controlled tertiary setting. A prospective randomized trial would be necessary to determine whether tocolytic use carries any benefits. (Am J Obstet Gynecol 1999;180:1572-8.)     

Association of caesarean delivery for first birth with placenta praevia and placental abruption in second pregnancy

Objective  To quantify the risk of placenta praevia and placental abruption in singleton, second pregnancies after a caesarean delivery of the first pregnancy.
Design  Retrospective cohort study.
Setting  Linked birth and infant mortality database of the USA between 1995 and 2000.
Population  A total of 5 146 742 singleton second pregnancies were available for the final analysis after excluding missing information.
Methods  Multiple logistic regressions were used to describe the relationship between caesarean section at first birth and placenta praevia and placental abruption in second-birth singletons.
Main outcome measures  Placenta praevia and placental abruption.
Results  Placenta praevia was recorded in 4.4 per 1000 second-birth singletons whose first births delivered by caesarean section and 2.7 per 1000 second-birth singletons whose first births delivered vaginally. About 6.8 per 1000 births were complicated with placental abruption in second-birth singletons whose first births delivered by caesarean section and 4.8 per 1000 birth in second-birth singletons whose first births delivered vaginally. The adjusted odds ratio (95% CIs) of previous caesarean section for placenta praevia in following second pregnancies was 1.47 (1.41, 1.52) after controlling for maternal age, race, education, marital status, maternal drinking and smoking during pregnancy, adequacy of prenatal care, and fetal gender. The corresponding figure for placental abruption was 1.40 (1.36, 1.45).
Conclusion  Caesarean section for first live birth is associated with a 47% increased risk of placenta praevia and 40% increased risk of placental abruption in second pregnancy with a singleton.     

Systematic multidisciplinary approach to reporting perinatal mortality: Lessons from a five-year regional review

Background:  Because of differences in reporting criteria throughout the world, comparing perinatal mortality rates and identifying areas of concern can be complicated and imprecise.
Aims:  To detail the systematic approach to reporting perinatal deaths and to identify any significant differences in outcomes in the Australian Capital Territory (ACT).
Methods:  Review of perinatal deaths from 2001 to 2005 in the ACT using the Australian and New Zealand Antecedent Classification of Perinatal Mortality (ANZACPM) and the Australian and New Zealand Neonatal Death Classification (ANZNDC) systems.
Results:  ACT residents' perinatal mortality rate was 10.6 per 1000 total births, fetal death rate 7.5 per 1000 total births and neonatal death rate 3.2 per 1000 live births. The three leading antecedent causes of perinatal death were congenital anomalies, spontaneous preterm birth and unexplained antepartum death. The three leading causes of neonatal death were extreme prematurity, cardiorespiratory disorders and congenital anomalies. Multiple births attributed to 20% (65 of 321) of perinatal deaths. Perinatal autopsy was performed in 50% of cases, but in only 64% of unexplained antepartum deaths.
Conclusions:  Causes of perinatal death for the ACT and surrounding New South Wales region are similar to other states using this classification system. The following are considered important lessons to promote accurate perinatal mortality reporting: (i) a universal reporting system for Australia utilising a multidisciplinary team; (ii) a high perinatal autopsy rate, especially in the critical area of antepartum death with no identifiable cause; and (iii) standardised definitions for avoidability. Attention to these areas may prompt further research and changes in practice to further reduce perinatal mortality.     

A comparative study of neonatal outcomes in placenta previa versus cesarean for other indication at term

Abstract

Objective: Currently, no ACOG guidelines address the issue of the optimal timing of delivery in placenta previa. Though there is an increased risk of neonatal morbidity and mortality when electively delivered preterm, it is unclear whether adverse neonatal outcomes exist when these pregnancies make it beyond term. By comparing neonatal outcomes amongst pregnancies with placenta previa versus those from cesarean for another indication at term, the objective of this study was to determine whether placenta previa is an independent risk factor for adverse neonatal outcomes at term.

Methods: We conducted a population-based cohort-study using the CDC’s Linked Birth–Infant Death data from the United States. The effect of placenta previa on the risk of adverse neonatal outcomes was estimated using unconditional logistic regression analysis, adjusting for relevant confounders.

Results: Our cohort consisted of 3?550?842 deliveries meeting inclusion criteria. The incidence of placenta previa at term was 1.3/1000 (n?=?4,492), accounting for 40.6% of all previa cases. Relative to cesareans for other indications, pregnancies with placenta previa had an increased risk of IUGR 3.20 [2.50–4.10], SGA 2.70 [2.45–2.97], respiratory distress 3.82 [2.91–5.00], prolonged ventilation 3.41 [2.70–4.32] and neonatal anemia 6.87 [4.43–10.65]. Rates of meconium aspiration syndrome, seizures, birth injury and overall infant mortality do not appear to be affected by this condition.

Conclusion: Relative to cesareans for other indications, placenta previa is associated with increased morbidity, but not mortality, at term. This information might be helpful in the development of future guidelines, which are currently needed to guide and standardize clinical practice regarding the optimal timing of delivery in placenta previa.     

The Egypt National Perinatal/Neonatal Mortality Study 2000.

OBJECTIVES: To estimate stillbirth, perinatal (PMR) and neonatal mortality rates (NMR) in Egypt and to assign main causes of death. STUDY DESIGN: Data were collected from a representative sample of women who gave birth from 17,521 households which were included in the Egypt Demographic and Health Survey (EDHS) 2000. Comparisons were made between three systems for classifying causes of death. RESULTS: The NMR was 25 per 1000 live births (17 early and eight late). Half the deaths occurred in the first two days of life. Neonatal causes of death were pre-maturity (39%), asphyxia (18%), infections (7%), congenital malformation (6%) and unclassified (29%). The PMR was 34 per 1000 births, mainly attributed to: asphyxia (44%) and prematurity (21%). The revised Wigglesworth classification agreed well with the physicians except the panel attributed more deaths to infections (20%). The WHO verbal autopsy algorithm left 48% of deaths unclassified. CONCLUSIONS: Infant mortality in Egypt is showing an epidemiological transition with a significant decrease in mortality, resulting in a disproportionate percentage of deaths in the first week of life. Infant mortality in Egypt declined 64% from 124 per 1000 between 1974 and 1978 to 44 per 1000 between 1995 and 1999, the decline being greatest among older infants; 55% of all infant deaths occurred during the neonatal period. The neonatal mortality rate in this study was estimated to be 25 per 1000 live births.     

Prolonged pregnancy: evaluating gestation-specific risks of fetal and infant mortality

Objective To evaluate gestation-specific risks of stillbirth, neonatal and post-neonatal mortality.
Design Retrospective analysis of 171,527 notified births (1989–1991) and subsequent infant survival at one year, from community child health records.
Setting Notifications from maternity units in the North East Thames Region, London.
Main outcome measures The incidence of births, stillbirths, neonatal and post-neonatal deaths at each gestation after 28 completed weeks. Mortality rates per 1000 total or live births and per 1000 ongoing pregnancies at each gestation were calculated.
Results The rates of stillbirth at term (2.3 per 1000 total births) and post-term (1.9 per 1000 total births) were similar. When calculated per 1000 ongoing pregnancies, the rate of stillbirth increased six-fold from 0.35 per 1000 ongoing pregnancies at 37 weeks to 2.12 per 1000 ongoing pregnancies at 43 weeks of gestation. Neonatal and post-neonatal mortality rates fell significantly with advancing gestation, from 15 1.4 and 31.7 per 1000 live births at 28 weeks, to reach a nadir at 41 weeks of gestation (0.7 and 1.3 per 1000 live births, respectively), increasing thereafter in prolonged gestation to 1.6 and 2.1 per 1000 live births at 43 weeks of gestation. When calculated per 1000 ongoing pregnancies, the overall risk of pregnancy loss (stillbirth + infant mortality) increased eight-fold from 0.7 per 1000 ongoing pregnancies at 37 weeks to 5.8 per 1000 ongoing pregnancies at 43 weeks of gestation.
Conclusion The risks of prolonged gestation on pregnancy are better reflected by calculating fetal and infant losses per 1000 ongoing pregnancies. There is a significant increase in the risk of stillbirth, neonatal and post-neonatal mortality in prolonged pregnancy. This study provides accurate data on gestation-specific risks of pregnancy loss, enabling pregnant women and their carers to judge the appropriateness of obstetric intervention.     

Relationship among placenta previa, fetal growth restriction, and preterm delivery: a population-based study

OBJECTIVE: To examine the independent contributions of prematurity and fetal growth restriction to low birth weight among women with placenta previa. METHODS: A population-based, retrospective cohort study of singleton live births in New Jersey (1989-93) was performed. Mother-infant pairs (n = 544,734) were identified from linked birth certificate and maternal and infant hospital discharge summary data. Women diagnosed with previa were included only if they were delivered by cesarean. Fetal growth, defined as gestational age-specific observed-to-expected mean birth weight, and preterm delivery (before 37 completed weeks) were examined in relation to previa. Severe and moderate categories of fetal smallness and large for gestational age were defined as observed-to-expected birth weight ratios below 0.75, 0.75-0.85, and over 1.15, respectively, all of which were compared with appropriately grown infants (observed-to-expected birth weight ratio 0.86-1.15). RESULTS: Placenta previa was recorded in 5.0 per 1000 pregnancies (n = 2744). After controlling for maternal age, education, parity, smoking, alcohol and illicit drug use, adequacy of prenatal care, maternal race, as well as obstetric complications, previa was associated with severe (odds ratio [OR] 1.37, 95% confidence interval [CI] 1.25, 1.50) and moderate fetal smallness (OR 1.24, 95% CI 1.17, 1.32) births. Preterm delivery was also more common among women with previa. Adjusted OR of delivery between 20-23 weeks was 1.81 (95% CI 1.24, 2.63), and 2.90 (95% CI 2.46, 3.42) for delivery between 24-27 weeks. OR for delivery by each week between 28 and 36 weeks ranged between 2.7 and 4.0. Approximately 12% of preterm delivery and 3.7% of growth restriction were attributable to placenta previa. CONCLUSION: The association between low birth weight and placenta previa is chiefly due to preterm delivery and to a lesser extent with fetal growth restriction. The risk of fetal smallness is increased slightly among women with previa, but this association may be of little clinical significance.     

前置胎盘合并剖宫产史临床分析

目的探讨前置胎盘合并剖宫产史患者的临床特点及处理。方法回顾性分析2003年1月至2011年10月北京协和医院前置胎盘合并剖宫产史（再次剖宫产组,RCS组）患者母婴结局,并与同期前置胎盘行初次剖宫产（初次剖宫产组,FCS组）进行比较。结果 RCS组及FCS组分别有29例及243例患者。两组的平均年龄、孕周差异无统计学意义（P〉0.05）。RCS组患者手术时间长,产后出血量多,早产、产后出血、胎盘植入、输血、弥漫性血管内凝血和产科子宫切除的发生率均高于FCS组,差异有统计学意义（P〈0.05）,RCS组早产儿、新生儿窒息发生率及围产儿死亡率均高于FCS组（P〈0.05）。结论前置胎盘合并剖宫产史更易发生胎盘植入,产后出血、产科子宫切除及围产儿病率高,需要高度重视。     

Causes and consequences of recent increases in preterm birth among twins.

OBJECTIVE: To examine the causes and consequences of the recent increase in preterm birth among twins. METHODS: We studied all twin births among residents of the province of Nova Scotia, Canada, between 1988 and 1997. Rates of preterm birth, preterm labor induction, preterm cesarean, small-for-gestational age (SGA), respiratory distress syndrome (RDS), stillbirth, perinatal mortality, and infant mortality were compared between past and more recent years. Changes in perinatal mortality were examined using logistic regression to adjust for the effects of other determinants. RESULTS: The study included 2516 twin births (73 stillbirths and 2443 live births). The rate of preterm birth increased from 42.3% in 1988-1992 to 48.2% of twin live births in 1993-1997 (14% increase, P =.04). Twin live births born after preterm labor induction increased from 3.5% in 1988-1989 to 8.6% in 1996-1997 (P for trend =.007). Of live births between 34 and 36 weeks' gestation, the proportion born SGA decreased from 17.5% in 1988-1992 to 9.2% in 1993-1997 (P =.005). Over the same period, rates of prophylactic maternal steroid therapy increased substantially and rates of RDS declined. Perinatal mortality rates among pregnancies reaching 34 weeks decreased from 12.9 per 1000 total births in 1988-1992 to 4.2 per 1000 total births in 1993-1997 (P =.05). CONCLUSION: Increases in preterm labor induction appear to be responsible for the recent increase in preterm birth among twins. These changes have been accompanied by decreases in perinatal morbidity and mortality among twin pregnancies that reach 34 weeks' gestation.     

Placenta previa and the risk of preterm delivery

Objectives. We aimed to quantify the risk of preterm delivery and maternal and neonatal morbidities associated with placenta previa.

Study design. We conducted a retrospective cohort study of singleton births that occurred between 1976 and 2001, examining outcomes including preterm delivery and perinatal complications. Multivariate logistic regression was used to control for potential confounders. Kaplan–Meier survival curves were constructed to compare preterm delivery in pregnancies complicated by previa vs. no previa.

Results. Among the 38 540 women, 230 women had previas (0.6%). Compared to controls, pregnancies with previa were significantly associated with preterm delivery prior to 28 weeks (3.5% vs. 1.3%; p = 0.003), 32 weeks (11.7% vs. 2.5%; p < 0.001), and 34 weeks (16.1% vs. 3.0%; p < 0.001) of gestation. Patients with previa were more likely to be diagnosed with postpartum hemorrhage (59.7% vs. 17.3%; p < 0.001) and to receive a blood transfusion (11.8% vs. 1.1%; p < 0.001). Survival curves demonstrate the risk of preterm delivery at each week and showed an overall higher rate of preterm delivery for patients with a placenta previa.

Conclusions. Placenta previa is associated with maternal and neonatal complications, including preterm delivery and postpartum hemorrhage. These specific outcomes can be used to counsel women with previa.     

ACOG practice bulletin no. 127: Management of preterm labor

Preterm birth is the leading cause of neonatal mortality and the most common reason for antenatal hospitalization(1–4). In the United States, approximately 12% of all live births occur before term, and preterm labor preceded approximately 50% of these preterm births (5, 6). Although the causes of preterm labor are not well understood, the burden of preterm births is clear—preterm births account for approximately 70% of neonatal deaths and 36% of infant deaths as well as 25–50% of cases of long-term neurologic impairment in children (7–9). A 2006 report from the Institute of Medicine estimated the annual cost of preterm birth in the United States to be $26.2 billion or more than$51,000 per premature infant (10). However, identifying women who will give birth preterm is an inexact process.The purpose of this document is to present the various methods proposed to manage preterm labor and to review the evidence for the roles of these methods in clinical practice. Identification and management of risk factors for preterm labor are not addressed in this document.     

Perinatal mortality in first- and second-born twins in the United States

OBJECTIVE: To evaluate the prevailing mortality paradox that second-born twins are at higher risk of perinatal mortality than first-born twins. METHODS: We used the 1995-1997 United States "matched multiple birth" data files assembled by the National Center for Health Statistics, for analysis of risk of perinatal mortality in first- and second-born twins (293788 fetuses). Perinatal mortality was defined to include stillbirths after 20 weeks of gestation and neonatal deaths (deaths within the first 28 days). Gestational age-specific risk of perinatal mortality (per 1000 total births), stillbirth (per 1000 total births), and neonatal mortality (per 1000 livebirths) by order of twin birth were based on the fetuses-at-risk approach. Associations between order of birth and mortality indices were evaluated by fitting multivariable logistic regression models based on the method of generalized estimating equations. These models were adjusted for several potential confounding factors. RESULTS: Perinatal mortality was 37% higher in second-born (26.1 per 1000 total births) than in first-born (20.3 per 1000 total births) twins (adjusted relative risk [RR] 1.37; 95% confidence interval [CI] 1.32, 1.42). The increased risk of perinatal mortality in second-born twins was chiefly driven by a 2.46-fold (95% CI 2.29, 2.63) increase in the number of stillbirths. However, the risk of neonatal mortality was very similar between first- and second-born twins (RR 0.99, 95% CI 0.95, 1.04). CONCLUSIONS: The increased risk of perinatal death in second-born twins is driven chiefly by increased rates of stillborn second twins. Thus, the increased mortality in second-born over first-born twins probably is an artifact of mortality comparisons.     

The burden of disease from neonatal mortality: a review of South Asia and Sub-Saharan Africa

Objective To assess the burden of neonatal mortality in two developing regions.
Design Review of secondary data collated through literature review.
Setting Community and facility based studies and national health surveys.
Population Neonatal (<28 days) population of South Asia and Sub-Saharan Africa.
Methods Data on neonatal mortality were gathered from peer-reviewed literature, reports of the Demographic and Health Surveys and websites of country-based organisations. The base year for this study is 1995. For each country, a weighted mean neonatal mortality rate was calculated and the total number of neonatal deaths estimated. Country data were summarised over each region to estimate annual regional neonatal deaths and rates. The burden of disease from neonatal mortality was determined using a summary measure of health—healthy life years.
Main outcome measures Numbers of deaths and healthy life years (HeaLYs).
Results Neonatal mortality rate for South Asia ranged from 41.9 to 56.9 per 1000 live births for 1995. Sri Lanka was an exception with a neonatal mortality rate between 16.3 and 18.6 per 1000 live births. The estimated regional neonatal mortality rate for South Asia was 46.27 per 1000 live births for 1995. There was a significant lack of data from Sub-Saharan Africa, resulting in highly variable neonatal mortality rates, ranging from 13 per 1000 live births in Kenya to 108 per 1000 live births in Senegal. The mean regional neonatal mortality for Sub-Saharan Africa for 1995 was estimated at 38.8 per 1000 live births.
Conclusion The burden of neonatal mortality in only these two regions of the developing world represents more than 2 million annual deaths. A call for greater investments in neonatal research and health programs is a logical extension to this review of evidence.