Recurrence of preterm birth in singleton and twin pregnancies

OBJECTIVE: To assess recurrence of preterm birth and its impact on an obstetric population. METHODS: Women with consecutive births at our hospital beginning with their first pregnancy were identified (n = 15,945). The first pregnancy was categorized as delivered between 24 and 34 weeks' gestation or 35 weeks or beyond, singleton or twin, and spontaneous or induced. The risk of preterm delivery in these same women during subsequent pregnancies was then analyzed. RESULTS: Compared with women who delivered a singleton at or beyond 35 weeks' gestation in their first pregnancy, those who delivered a singleton before 35 weeks were at a significant increased risk for recurrence (odds ratio [OR] 5.6, 95% confidence interval [CI] 4.5, 7.0), whereas those who delivered twins were not (OR 1.9, 95% CI 0.46, 8.14). The OR for recurrent spontaneous preterm birth presenting with intact membranes was 7.9 (95% CI 5.6, 11.3) compared with 5.5 (95% CI 3.2, 9.4) with ruptured membranes. Of those women with a recurrent preterm birth, 49% delivered within 1 week of the gestational age of their first delivery and 70% delivered within 2 weeks. Among 15,863 nulliparous women with singleton births at their first delivery, a history of preterm birth in that pregnancy could predict only 10% of the preterm births that ultimately occurred in the entire obstetric population. CONCLUSION: In a population-based study at our hospital, women who initially delivered preterm and thus were identified to be at risk for recurrence ultimately accounted for only 10% of the prematurity problem in the cohort.     

Recurrence of preterm birth in twin pregnancies in the presence of a prior singleton preterm birth

OBJECTIVE: We examined recurrence of preterm birth in twin pregnancy in the presence of a previous singleton preterm pregnancy, and assessed if these recurrence risks differed for medically indicated and spontaneous preterm birth. METHODS: A retrospective cohort study was designed using the maternally-linked data of women who delivered a first singleton live birth followed by a twin birth in the second pregnancy (n = 2329) in Missouri (1989--97). We examined preterm birth recurrence at <37 in the second twin pregnancy among women with a prior singleton preterm birth. Recurrence risks were based on hazard ratios (HR) and 95% confidence intervals (CI) estimated from Cox proportional hazards models after adjusting for potential confounders. RESULTS: Preterm birth rates in the second twin pregnancy were 69.0% and 49.9% among women who had a previous preterm and term singleton birth, respectively (HR 1.8, 95% CI 1.6-2.1). The preterm birth rate in the second pregnancy was about 95% when the first singleton pregnancy ended at <30 weeks. Women delivering preterm following a medical intervention in the first pregnancy had increased recurrence for both spontaneous (HR 1.4, 95% CI 1.1-2.0) and indicated (HR 2.4, 95% CI 1.8-3.2) preterm birth; similarly among women with a prior spontaneous preterm birth, hazard ratios were 1.8 (95% CI 1.5-2.1) and 1.6 (95% CI 1.3-1.9), for spontaneous and indicated preterm birth in the second twin pregnancy, respectively. CONCLUSIONS: Women with a singleton preterm birth carry increased risk of preterm birth in the subsequent twin pregnancy. A history of a singleton preterm birth has an independent and additive contribution to risk of preterm birth in the subsequent twin gestation.     

Multiple cesarean section morbidity.

OBJECTIVE: To quantify maternal risk associated with multiple cesarean sections (CSs) and determine whether the third CS defines a threshold for increased morbidity. METHODS: From January 1997 to January 2002, the clinical records of 3191 women who were delivered by CS at our referral maternity center were examined for selected indicators of maternal morbidity. The women were assigned to groups based on number of CSs and the frequency of each indicator was determined. A composite score for each indicator among women grouped by number of consecutive CSs was then derived to compare risk between groups and against the third CS. RESULTS: By all indicators studied, morbidity increased with successive CSs before and through the third CS. However, compared with the third, the risk of major morbidity was significantly increased with the fifth, and much worse at the sixth CS for placenta previa (odds ratio [OR]=3.8, 95% confidence interval [CI]=1.9-7.4), placenta accreta (OR=6.1, 95% CI=2.0-18.4) and hysterectomy (OR=5.9, 95% CI=1.5-24.4). But the third and fourth CSs had the same risk of major morbidity for placenta previa (OR=1.4, 95% CI=0.8-2.2), placenta accreta (OR=1.0, 95% CI=0.3-2.9) and hysterectomy (OR=0.3, 95% CI=0.0-2.7). CONCLUSIONS: The third CS does not define a threshold for increased risk to the mother. Instead, overall morbidity rises continually with each successive CS. However, specifically for major morbidity from the triad of placenta previa, placenta accreta and hysterectomy during CS, the fourth CS carries the same risk as the third.     

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.     

The impact of interpregnancy interval and previous preterm birth on the subsequent risk of preterm birth

OBJECTIVE: To examine the impact of the interpregnancy interval and a previous preterm birth on the subsequent risk of a preterm birth. METHODS: A retrospective analysis was conducted on a group of 4072 women who had at least two consecutive births, excluding multiple gestation, fetal anomalies, cervical incompetence, and stillbirth. Multivariate logistic regression was used to investigate the association between interpregnancy interval, preterm birth of the first child in the pair (index pregnancy), and the risk of a preterm birth of the second child in the pair (outcome pregnancy). RESULTS: Women with interpregnancy intervals of less than 12 months (odds ratio [OR] 1.3; 95% confidence interval [CI] 1.0-1.7) were at increased risks of preterm birth with the outcome pregnancy. Furthermore, there was an increased risk for a subsequent preterm birth in women who had a preterm birth in the index pregnancy (OR 4.2; 95% CI 3.0-6.0). The risk decreased as the interpregnancy interval increased, with a relatively low risk at 18 to 48 months; subsequently, it increased sharply. In contrast, women who had delivered their previous infants at term carried an increased risk of preterm birth with the outcome pregnancy only if the interval was less than 6 months. CONCLUSION: A difference was found in the impact of the interpregnancy interval on the subsequent risk of preterm birth between women with a prior preterm birth and those who previously delivered an infant at term.     

Pregnancy outcome following recurrent spontaneous abortions

OBJECTIVE: The purpose of the present study was to examine the association between spontaneous consecutive recurrent abortions and pregnancy complications such as hypertensive disorders, abruptio placenta, intrauterine growth restriction and cesarean section (CS) in the subsequent pregnancy. METHODS: A population-based study comparing all singleton pregnancies in women with and without two or more consecutive recurrent abortions was conducted. Deliveries occurred during the years 1988-2002. Stratified analysis, using a multiple logistic regression model was performed to control for confounders. RESULTS: During the study period 154,294 singleton deliveries occurred, with 4.9% in patients with history of recurrent consecutive abortions. Using a multivariate analysis, with backward elimination, the following complications were significantly associated with recurrent abortions-advanced maternal age, cervical incompetence, previous CS, diabetes mellitus, hypertensive disorders, placenta previa and abruptio placenta, mal-presentations and PROM. A higher rate of CS was found among patients with previous spontaneous consecutive recurrent abortions (15.9% versus 10.9%; OR = 1.6; 95% CI, 1.5-1.7; P < 0.001). Another multivariate analysis was performed, with CS as the outcome variable, controlling for confounders such as placenta previa, abruptio placenta, diabetes mellitus, hypertensive disorders, previous CS, mal-presentations, fertility treatments and PROM. A history of recurrent abortion was found as an independent risk factor for CS (OR = 1.2; 95% CI, 1.1-1.3; P < 0.001). About 58 cases of inherited thrombophilia were found between the years 2000-2002. These cases were significantly more common in the recurrent abortion as compared to the comparison group (1.2% versus 0.1%; OR = 11.1; 95% CI, 6.5-18.9; P < 0.001). CONCLUSION: A significant association exists between consecutive recurrent abortions and pregnancy complications such as placental abruption, hypertensive disorders and CS. This association persists after controlling for variables considered to coexist with recurrent abortions. Careful surveillance is required in pregnancies following recurrent abortions, for early detection of possible complications.     

Risk of preterm delivery in relation to maternal low birth weight

OBJECTIVE: We examined the relationship between maternal low birth weight and preterm delivery risk. METHODS: Information concerning maternal birth weight was collected during in-person interviews. Logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (95% CI). Preterm delivery cases were studied in aggregate, in subgroups (spontaneous preterm labor, preterm premature rupture of membranes, medically induced preterm delivery, moderate preterm delivery [gestational age at delivery 34-36 weeks], and early preterm delivery [gestational age at delivery<34 weeks]). RESULTS: After adjusting for confounders, women weighing<2,500 g at birth had a 1.54-fold increased risk of preterm delivery versus women weighing=2,500 g (95% CI 0.97-2.44). Maternal low birth weight was associated with a 2-fold increased risk of spontaneous preterm delivery (95% CI 1.03-3.89), but weakly associated with preterm premature rupture of membranes (OR=1.44; 95% CI 0.67-3.09) and medically induced preterm delivery (OR=1.10; 95% CI 0.43-2.82). Maternal low birth weight was more strongly associated with early preterm delivery (OR=1.94) than with moderate preterm delivery (OR=1.46). Women weighing<2,500 g at birth and who became obese (pre-pregnancy body mass index, =30 kg/m2) before pregnancy had a 3.65-fold increased risk of preterm delivery (95% CI 1.33-10.02) versus women weighing=2,500 g at birth and who were not obese prior to pregnancy (<30 kg/m2). CONCLUSIONS: Results confirm earlier findings linking maternal low birth weight with future risk of preterm delivery.     

Risk factors for placenta previa in an Asian population.

OBJECTIVE: To identify the risk factors for placenta previa in an Asian population. METHODS: This retrospective cohort study involved Taiwanese women delivered between July 1990 and December 2003 at Chang Gung Memorial Hospital, Taipei, Taiwan. Pregnancies complicated by multiple gestation and fetal anomalies were excluded. RESULTS: There were 457 cases of placenta previa (1.2%) among the 37,702 pregnancies analyzed. Risk factors for placenta previa included a prior preterm birth (OR, 6.6; 95% confidence interval [CI], 4.1-10.6); technology-assisted conception (OR, 4.8; 95% CI, 2.9-7.8); smoking (OR, 3.3; 95% CI, 1.2-9.1) or working (OR, 3.8; 95% CI, 2.8-5.3) during pregnancy; maternal age of, or greater than 35 years (OR, 2.0 to 2.2; 95% CI, 1.3-3.7); and previous induced abortions (OR, 1.3-3.0; 95% CI, 1.1-7.1). CONCLUSION: The risk factors for placenta previa were found to be the same for Asian women as those previously recorded for American and European women, but additional factors were detected.     

Bacterial vaginosis and group B streptococcal colonization and preterm delivery in a low-risk population

OBJECTIVE: To evaluate the relationship between bacterial vaginosis (BV) and group B streptococcal (GBS) colonization in the 2nd trimester of pregnancy and preterm delivery. METHODS: 1,197 pregnant women between 22 and 25 weeks' gestation had a high vaginal swab for assessment of BV and GBS. Exclusion criteria were: previous preterm delivery, or mid-trimester abortion or termination of pregnancy, multiple gestation, oligo- or polyhydramnios, placenta previa, fetal abnormalities, uterine malformations, cervical incompetence, cervical cerclage, or receipt of an antibiotic effective against BV or GBS following the screening. All women had no risk factors for preterm delivery. The primary outcome measure in this analysis was spontaneous preterm delivery before 37 weeks' gestation. RESULTS: The preterm delivery rate was 8.7%, while the maternal BV and GBS colonization rates were 7.9 and 12.5%, respectively. Following adjustment for potential confounders BV was associated with an increased risk of preterm delivery (RR 2.19; CI: 1.21-3.98) (p = 0.01). On the contrary, GBS colonization was found to have a negative correlation with preterm birth (RR 0.43; 95% CI: 0.19-1.00). CONCLUSIONS: Although BV is a risk factor for preterm delivery, GBS colonization in the 2nd trimester of pregnancy has an inverse correlation with preterm delivery.     

Prevalence and risk factors related to preterm birth in Brazil

Background

The rate of preterm birth has been increasing worldwide, including in Brazil. This constitutes a significant public health challenge because of the higher levels of morbidity and mortality and long-term health effects associated with preterm birth. This study describes and quantifies factors affecting spontaneous and provider-initiated preterm birth in Brazil.

Methods

Data are from the 2011–2012 “Birth in Brazil” study, which used a national population-based sample of 23,940 women. We analyzed the variables following a three-level hierarchical methodology. For each level, we performed non-conditional multiple logistic regression for both spontaneous and provider-initiated preterm birth.

Results

The rate of preterm birth was 11.5 %?, (95 % confidence 10.3 % to 12.9 %) 60.7 % spontaneous - with spontaneous onset of labor or premature preterm rupture of membranes - and 39.3 % provider-initiated, with more than 90 % of the last group being pre-labor cesarean deliveries. Socio-demographic factors associated with spontaneous preterm birth were adolescent pregnancy, low total years of schooling, and inadequate prenatal care. Other risk factors were previous preterm birth (OR 3.74; 95 % CI 2.92–4.79), multiple pregnancy (OR 16.42; 95 % CI 10.56–25.53), abruptio placentae (OR 2.38; 95 % CI 1.27–4.47) and infections (OR 4.89; 95 % CI 1.72–13.88). In contrast, provider-initiated preterm birth was associated with private childbirth healthcare (OR 1.47; 95 % CI 1.09–1.97), advanced-age pregnancy (OR 1.27; 95 % CI 1.01–1.59), two or more prior cesarean deliveries (OR 1.64; 95 % CI 1.19–2.26), multiple pregnancy (OR 20.29; 95 % CI 12.58–32.72) and any maternal or fetal pathology (OR 6.84; 95 % CI 5.56–8.42).

Conclusion

The high proportion of provider-initiated preterm birth and its association with prior cesarean deliveries and all of the studied maternal/fetal pathologies suggest that a reduction of this type of prematurity may be possible. The association of spontaneous preterm birth with socially-disadvantaged groups reaffirms that the reduction of social and health inequalities should continue to be a national priority.

     

Pregnancy outcome in women aged 40 years or more

Objective: The study aimed to analyze the pregnancy outcome of women aged 40 years or more. Methods: A matched retrospective cohort study comparing women aged 40 years or more with a control group aged 20 to 30 years is described. Multivariate logistic regression models were fitted for the prediction of preterm birth and cesarean delivery. Results: Pregnancy-induced hypertension, preeclampsia and placenta previa were similar in both groups, but a higher rate of gestational diabetes was found in elderly patients (odds ratio [OR] 3.820, 95% confidence interval [CI] = 1.400–10.400; p < 0.0001). Preterm delivery was significantly more frequent in elderly women (OR 1.847, 95% CI = 1.123–3.037; p = 0.020). Gestational diabetes and pregnancy-induced hypertension were strongly associated with preterm delivery and advanced maternal age was not an independent risk factor for preterm delivery. The cesarean delivery rate was significantly higher in the study group (OR 3.234, 95% CI = 2.266–4.617; p < 0.0001). The variables most influencing the cesarean delivery rate were maternal age, analgesia, parity, premature rupture of the membranes and gestational hypertension. No significant differences were detected in neonatal birth weight and Apgar score. Conclusions: Patients aged 40 years or more have been demonstrated to carry a favorable pregnancy and neonatal outcome, similar to younger patients. The risk of cesarean delivery was higher in patients with advanced maternal age, in nulliparous and in women with a previous cesarean section. The risk of preterm delivery was not related to age but it was strongly associated with gestational diabetes and pregnancy-induced hypertension.     

Previous cesarean section and abortion as risk factors for developing placenta previa.

OBJECTIVE: To determine the risk of subsequent occurrence of placenta previa in women with a history of previous cesarean sections and/or spontaneous and induced abortions. METHODS: A retrospective analysis of all single gestation deliveries at National University Hospital of Singapore from 1993-1997 was done. Women with placenta previa were identified by clinical or ultrasonographic diagnosis. RESULTS: Of the 16,169 singleton deliveries, 164 women (1.0%) had placenta previa. Women with placenta previa had a significantly higher incidence of previous cesarean sections (p < 0.001). Among the 164 women with placenta previa, women with 1, 2, and 3 previous cesarean sections had 2.2 (95% CI 1.4, 3.4), 4.1 (95% CI 1.9, 8.8) and 22.4 (95% CI 6.4, 78.3) times increased risk of developing placenta previa respectively. Similarly, women with 2 or more previous abortions had a 2.1 (95% CI 1.2, 3.5) times increased risk of subsequently developing placenta previa. CONCLUSION: There is a strong association between previous cesarean section and risk of subsequent development of placenta previa. This risk increased with the number of previous cesarean sections. Increasing frequency of abortions was also found to predispose a woman to placenta previa.     

Association between maternal serum alpha-fetoprotein and adverse outcomes in pregnancies with placenta previa

OBJECTIVE: To determine whether increased maternal serum alpha-fetoprotein (MSAFP) level at 15-20 weeks' gestation is a marker of adverse outcomes in women with placenta previa at delivery. METHODS: We conducted a retrospective cohort study of singleton pregnancies complicated by placenta previa, diagnosed sonographically, and confirmed at delivery. All women had MSAFP screening at 15-20 weeks' gestation and delivered nonanomalous live-born infants at or after 24 weeks' gestation. RESULTS: One hundred seven women with placenta previa delivered during the study. Fourteen (13%, 95% CI 7%, 21%) had MSAFP at least 2.0 multiples of the median (MoM). They were significantly more likely than those with lower MSAFP levels to have one or more of the following outcomes: hospitalization for antepartum bleeding before 30 weeks' gestation (50% versus 15%), delivery before 30 weeks' gestation (29% versus 5%), or preterm delivery for pregnancy-associated hypertension before 34 weeks' gestation (14% versus none). The MSAFP cutoff of 2.0 MoM provided the best combination of sensitivity and specificity for those outcomes, using receiver operating characteristic curves. CONCLUSION: Women with placenta previa who also have high MSAFP levels are at increased risk of bleeding in the early third trimester and preterm birth. We did not find women who required cesarean hysterectomy, including those with placenta accreta, to consistently have elevated MSAFP.     

The likelihood of placenta previa with greater number of cesarean deliveries and higher parity

OBJECTIVE: To examine the relationship between prior cesarean delivery and placenta previa. METHODS: A hospital-based, case-control study was conducted in which 316 multiparous women with placenta previa were identified. Controls consisted of 2051 multiparous women with spontaneous vaginal deliveries. Information on prior cesarean delivery was examined in three forms: as a dichotomous variable, as an ordinal variable, and as a set of three indicator variables for one, two, and three or more cesarean deliveries. Multivariable logistic regression modeling was used to obtain an adjusted estimate of this association. RESULTS: Women with a prior cesarean delivery were more likely to have a placenta previa than those without (odds ratio [OR] 1.59, 95% confidence interval [CI] 1.21, 2.08). The likelihood of placenta previa increased as both parity and number of cesarean deliveries increased. Thus, the adjusted OR for a primiparous woman with one cesarean delivery was 1.28 (95% CI 0.82, 1.99). For a woman who has four or more deliveries with only a single cesarean delivery, the OR increases to 1.72 (95% CI 1.12, 2.64). This trend continues with greater parity and a greater number of cesarean deliveries such that the likelihood of placenta previa for a woman with parity greater than four and greater than four cesarean deliveries was OR 8.76 (95% CI 1.58, 48.53). CONCLUSION: This study supports the association between prior cesarean delivery and placenta previa and demonstrates that the joint effect of parity and prior cesarean delivery is greater than that of either variable alone.     

Sleep disturbances during pregnancy are associated with cesarean delivery and preterm birth

Objective: The purpose of this study was to examine the associations of sleep disturbances during pregnancy with cesarean delivery and preterm birth.

Methods: In this prospective study, 688 healthy women with singleton pregnancy were selected from three hospitals in Chengdu, China 2013–2014. Self-report questionnaires, including the sleep quantity and quality as well as exercise habits in a recent month were administered at 12–16, 24–28, and 32–36 weeks’ gestation. Data on type of delivery, gestational age, and the neonates’ weight were recorded after delivery. After controlling the potential confounders, a serial of multi-factor logistic regression models were performed to evaluate whether sleep quality and quantity were associated with cesarean delivery and preterm birth.

Results: There were 382 (55.5%) women who had cesarean deliveries and 32 (4.7%) who delivered preterm. Women with poor sleep quality during the first (OR: 1.87, 95% CI [1.02–3.43]), second (5.19 [2.25–11.97]), and third trimester (1.82 [1.18–2.80]) were at high risk of cesarean delivery. Women with poor sleep quality during the second (5.35 [2.10–13.63]) and third trimester (3.01 [1.26–7.19]) as well as short sleep time (<7?h) during the third trimester (4.67 [1.24–17.50]) were at high risk of preterm birth.

Conclusions: Sleep disturbances are associated with an increased risk of cesarean delivery and preterm birth throughout pregnancy. Obstetric care providers should advise women with childbearing age to practice healthy sleep hygiene measures.     

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.     

Previous cesarean delivery and risks of placenta previa and placental abruption

OBJECTIVE: To examine the association between cesarean delivery and previa and abruption in subsequent pregnancies. METHODS: A retrospective cohort study of first 2 (n = 156,475) and first 3 (n = 31,102) consecutive singleton pregnancies using the 1989-1997 Missouri longitudinally linked data were performed. Relative risk (RR) was used to quantify the associations between cesarean delivery and risks of previa and abruption in subsequent pregnancies, after adjusting for several confounders. RESULTS: Rates of previa and abruption were 4.4 (n = 694) and 7.9 (n = 1,243) per 1,000 births, respectively. The pregnancy after a cesarean delivery was associated with increased risk of previa (0.63%) compared with a vaginal delivery (0.38%, RR 1.5, 95% confidence interval [CI] 1.3-1.8). Cesarean delivery in the first and second births conferred a two-fold increased risk of previa in the third pregnancy (RR 2.0, 95% CI 1.3-3.0) compared with first two vaginal deliveries. Women with a cesarean first birth were more likely to have an abruption in the second pregnancy (0.95%) compared with women who had a vaginal first birth (0.74%, RR 1.3, 95% CI 1.2-1.5). Two consecutive cesarean deliveries were associated with a 30% increased risk of abruption in the third pregnancy (RR 1.3, 95% CI 1.0-1.8). A second pregnancy within a year after a cesarean delivery was associated with increased risks of previa (RR 1.7, 95% CI 0.9-3.1) and abruption (RR 1.5, 95% CI 1.1-2.3). CONCLUSION: A cesarean first birth is associated with increased risks of previa and abruption in the second pregnancy. There is a dose-response pattern in the risk of previa, with increasing number of prior cesarean deliveries. A short interpregnancy interval is associated with increased risks of previa and abruption. LEVEL OF EVIDENCE: II-2.     

Obstetric outcome in women with threatened miscarriage in the first trimester

OBJECTIVE: To assess pregnancy outcomes in women with threatened miscarriage in the first trimester. METHODS: This was a retrospective cohort study based on data extracted from the Aberdeen Maternity and Neonatal Databank. Cases included all primigravid women with first-trimester vaginal bleeding who delivered after 24 weeks of gestation between 1976 and 2004. The control group comprised all other women who had first pregnancies during the same period. Data were analyzed by univariate and multivariate statistical methods. RESULTS: Compared with the control group (n = 31,633), women with threatened miscarriage (n = 7,627) were more likely to have antepartum hemorrhage of unknown origin (odds ratio [OR] 1.83, 95% confidence interval [CI] 1.73-2.01). Elective cesarean (OR 1.30, 95% CI 1.14-1.48) and manual removal of placenta (OR 1.40, 95% CI 1.21-1.62) were performed more frequently in these women, who also had a higher risk of preterm delivery (OR 1.56, 95% CI 1.43-1.71) and malpresentation (OR 1.26, 95% CI 1.13-1.40). Threatened miscarriage in the first trimester is required in 112, 112, 17, 85, 32 patients, respectively, for each additional case of manual removal of placenta, elective cesarean, antepartum hemorrhage of unknown origin, malpresentation, and preterm delivery. CONCLUSION: Pregnancies complicated by threatened miscarriage are at a slightly higher risk of obstetric complications and interventions. LEVEL OF EVIDENCE: II-2.     

Risk of preterm delivery in relation to vaginal bleeding in early pregnancy

OBJECTIVE: To examine the relationship between vaginal bleeding during early pregnancy and preterm delivery. METHODS: Study subjects (N=2678) provided information regarding socio-demographic, biomedical, and lifestyle characteristics. Logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (95% CI). RESULTS: Any vaginal bleeding in early pregnancy was associated with a 1.57-fold increased risk of preterm delivery (95% CI: 1.16-2.11). Vaginal bleeding was most strongly related with spontaneous preterm labor (OR=2.10) and weakly associated with preterm premature rupture of membrane (OR=1.36) and medically induced preterm delivery (OR=1.32). As compared to women with no bleeding, those who bled during the first and second trimesters had a 6.24-fold increased risk of spontaneous preterm labor; and 2-3-fold increased risk of medically induced preterm delivery and preterm premature rupture of membrane, respectively. CONCLUSION: Vaginal bleeding, particularly bleeding that persists across the first two trimesters, is associated with an increased risk of preterm delivery.