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.     

Primary dysmenorrhea and risk of preterm delivery

Little is known about the mechanism and biochemical pathway of preterm delivery. Some drugs used to treat preterm labor are also useful for the treatment of primary dysmenorrhea. This study attempted to evaluate the association between primary dysmenorrhea and preterm delivery from an epidemiological perspective. A nested case-control study was conducted; 329 singleton preterm delivery cases were investigated, in aggregate and in subgroups (spontaneous preterm labor and preterm premature rupture of membranes). Concurrently, 329 singleton gravid women with term delivery served as controls. Medical charts and records provided information about the maternal history of dysmenorrhea, index pregnancy outcome, and demographic characteristics. Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using the multiple logistic regression method. Gravid women with a history of primary dysmenorrhea had no more risk of preterm delivery than those without a history of primary dysmenorrhea (adjusted OR, 1.16; 95% CI, 0.95 to 2.19; p=0.37). However, for subgroup analysis, gravid women with severe primary dysmenorrhea were associated with an adjusted 2.73-fold risk of spontaneous preterm delivery (95% CI, 1.49 to 4.95; p=0.02), and with an adjusted 1.51-fold risk of preterm premature rupture of membranes (95% CI, 0.68 to 3.22; p=0.31). Severe primary dysmenorrhea is associated with an increased risk of spontaneous preterm delivery. A common pathophysiologic pathway may exist between these two disorders. Further in-depth biochemical and molecular studies are necessary to explore this phenomenon.     

First trimester vaginal bleeding and adverse pregnancy outcomes among Chinese women: from a large cohort study in China

Objectives: To examine the effect of first trimester vaginal bleeding on adverse pregnancy outcomes including preterm delivery, low birth weight and small for gestational age. Methods: This is a prospective population-based cohort study. A questionnaire survey was conducted on 4342 singleton pregnancies by trained doctors. Binary logistic regression was used to estimate risk ratios (RRs) and 95% con?dence intervals (95% CI). Results: Vaginal bleeding occurred among 1050 pregnant women, the incidence of vaginal bleeding was 24.2%, 37.4% of whom didn’t see a doctor, 62.6% of whom saw a doctor for vaginal bleeding. Binary logistic regression demonstrated that bleeding with seeing a doctor was significantly associated with preterm birth (RR 1.84, 95% CI 1.25–2.69) and bleeding without seeing a doctor was related to increased of low birth weight (RR 2.52, 95% CI 1.34–4.75) and was 1.97-fold increased of small for gestational age (RR 1.97, 95% CI 1.19–3.25). Conclusions: These results suggest that first trimester vaginal bleeding is an increased risk of low birth weight, preterm delivery and small for gestational age. Find ways to reduce the risk of vaginal bleeding and lower vaginal bleeding rate may be helpful to reduce the incidence of preterm birth, low birth weight and small for gestational age.     

Risk factors for acute pulmonary edema in preterm delivery

OBJECTIVE: To determine the risk factors for pulmonary edema in women with preterm delivery. STUDY DESIGN: This was a case-controlled study of 52 (6.7%) cases with and 722 (93.3%) cases without pulmonary edema in a cohort of women who delivered between 24 and 33 weeks. Univariate and logistic regression analysis were used as indicated. RESULTS: Of subjects with pulmonary edema 98% received tocolytics while 94% had antenatal corticosteroid therapy versus 50% and 40% in controls. Significant positive associations of pulmonary edema only on univariate analysis were multiple pregnancy, earlier presenting gestational age, positive maternal cultures, small for gestational age while significant negative associations were indicated by preterm delivery and premature rupture of membranes. Independent predictors of pulmonary edema on logistic regression analysis were spontaneous preterm labor (odds ratio {OR}=10.9, p=0.026; 95% CI 1.3, 90), tocolytic therapy (OR=4.3, p=0.000; 95% CI 2.3, 8.4) especially magnesium sulfate and nifedipine, antenatal corticosteroid therapy (OR=2.3, p=0.002; 95% CI 1.3, 4), chorioamnionitis (OR=2.7, p=0.028; 95% CI 1.1, 6.5), blood product transfusion (OR=2.3, p=0.038; 95% CI 2.2, 8.4) and tobacco use (OR=2.5, p=0.016; 95% CI 1.2, 5.4). CONCLUSIONS: In mothers delivering prematurely, pulmonary edema is more likely with spontaneous preterm labor, smokers, infections or those receiving blood transfusions. It occurs almost exclusively in patients treated with antenatal corticosteroids and tocolytic medication.     

Adenomyosis and risk of preterm delivery

OBJECTIVE: To evaluate the risk of preterm delivery in patients with adenomyosis. DESIGN: A 1:2 nested case-control study. SETTING: Tertiary-care institution. POPULATION: A base cohort population of 2138 pregnant women who attended routine prenatal check-up between July 1999 and June 2005. METHODS: From this base cohort population, gravid women with singleton pregnancy who delivered prior to the completion of 37 weeks of gestation were identified and formed the study group. Singleton gravid women who had term delivery and who matched with age, body mass index, smoking, and status of previous preterm delivery were recruited concurrently and served as control group. Preterm delivery cases were further divided into spontaneous preterm delivery and preterm premature rupture of membranes (PPROM) cases. MAIN OUTCOME MEASURES: Risk analysis of preterm delivery between gravid women with and without adenomyosis. RESULTS: One-hundred and four preterm delivery case subjects and 208 control subjects were assessed. Overall, gravid women with adenomyosis were associated with significantly increased risk of preterm delivery (adjusted odds ratio 1.96, 95% CI 1.23-4.47, P=0.022). For subgroup analysis, gravid women with adenomyosis had an adjusted 1.84-fold risk of spontaneous preterm delivery (95% CI 1.32-4.31, P=0.012) and an adjusted 1.98-fold risk of PPROM (95% CI 1.39-3.15, P=0.017). CONCLUSIONS: Gravid women with adenomyosis were associated with increased risk of both spontaneous preterm delivery and PPROM. A common pathophysiological pathway may exist in these two disorders. Further in-depth biochemical and molecular studies are necessary to explore this phenomenon.     

早产临床风险因素的探讨

目的评估影响早产分娩的风险因素以及对早产干预措施影响的相关因素。方法选择2003年1月至2006年3月发生在34周前的自发性早产临产、早产胎膜早破、宫颈机能不全、先兆早产4种临床表现类型共221例,比较4种临床表现之间发病的风险因素及影响干预措施结局的相关因素。结果自发性早产临产的风险因素依次为:本次妊娠先兆流产史(OR8.917,95%CI2.308～34.457)、胎次(OR2.179,95%CI1.033～4.598)、宫颈长度改变(OR0.366,95%CI0.259～0.518);早产胎膜早破的风险因素依次为:自然流产史(OR4.922,95%CI1.115～21.720)、体外受精-胚胎移植(IVF-ET)(OR5.341,95%CI1.571～18.164);宫颈功能不全的风险因素依次为:早产史(OR9.010,95%CI2.032～39.940),IVF-ET(OR2.603,95%CI1.195～5.670)。发生早期早产分娩的影响因素依次为:血象升高(OR4.695,95%CI2.065～10.671)、宫颈长度变短(OR0.633,95%CI0.456～0.880)。对早产干预措施的影响因素为紧急宫颈环扎术(OR26.372,95%CI2.770～251.085)和血象升高(OR7.111,95%CI1.769～28.53)。结论影响早产的风险因素较多,应注重IVF-ET妊娠的早产风险;实施紧急宫颈环扎术及注重感染指标监测是减少34周前分娩的重要干预手段。     

Idiopathic bleeding during the second half of pregnancy as a risk factor for adverse perinatal outcome.

OBJECTIVE: To investigate pregnancy outcome in women suffering from idiopathic vaginal bleeding (IVB) during the second half of pregnancy. METHODS: A comparison between patients admitted to the hospital due to bleeding during the second half of pregnancy and patients without bleeding was performed. Patients lacking prenatal care as well as multiple gestations were excluded from the analysis. Stratified analyses using the Mantel-Haenszel technique and a multiple logistic regression model were performed to control for confounders. RESULTS: During the study period, 173,621 singleton deliveries occurred at our institute. Of these, 2077 (1.19%) were complicated with bleeding upon admission during the second half of pregnancy. After excluding cases with bleeding due to placental abruption, placenta previa, cervical problems, etc., 67 patients were classified as having IVB (0.038%). Independent risk factors associated with IVB, using a backward, stepwise multivariable analysis were oligohydramnios (OR=6.2; 95% CI 3.1-12.7; p < 0.001), premature rupture of membranes (OR=3.4; 95% CI 1.8-6.2; p < 0.001), intrauterine growth restriction (IUGR, OR 5.6; 95% CI 2.5-12.2; p < 0.001), and Jewish ethnicity (OR=1.9; 95% CI 1.0-3.5; p=0.036). These patients subsequently were more likely to deliver preterm (<37 weeks, 56.7% vs. 7.3%; mean gestational age of 33.6+/-5.7 weeks vs. 39.2+/-2.1 weeks; p < 0.001) and by cesarean delivery (CD, 35.8% vs. 12.1%, OR=4.0; 95% CI 2.4-6.6; p < 0.001). Higher rates of low Apgar scores (<7) at 1 and 5 minutes were noted in these patients (OR=10.3; 95% CI 5.9-17.8; p < 0.001 and OR=17.8; 95% CI 7.1-44.5; p < 0.001, respectively). Moreover, perinatal mortality rate among patients admitted due to idiopathic bleeding was significantly higher as compared to patients without bleeding (9.6% vs. 1.2%, OR=8.4; 95% CI 3.3-21.2; p < 0.001). However, when controlling for preterm delivery, using the Mantel-Haenszel technique, the association lost its significance. CONCLUSION: Idiopathic vaginal bleeding during the second half of pregnancy is a risk factor for adverse perinatal outcome, mostly due to its significant association with preterm delivery. Careful surveillance, including fetal monitoring, is suggested in these cases in order to reduce the adverse perinatal outcome.     

A prospective study of vaginal pH as a predictor of preterm delivery

Objective: To test the usefulness of vaginal pH determinations in the prediction of the risk of preterm delivery at or before 36 weeks of gestation. Methods: This was a prospective study of asymptomatic pregnant women. Vaginal pH was determined using pH paper in a sterile speculum examination during prenatal visits. Patients were followed to delivery and hospital records were reviewed to extract obstetric information. A total of 308 women agreed to participate and met the criteria for enrolment. Preterm delivery was defined as delivery at or prior to 36 weeks of gestation. Abnormal pH was defined as a pH of > 5.0. Results: Abnormal vaginal pH was associated with increased risk of preterm delivery, (OR 3.3, 95% CI 1.15, 9.2; p = 0.02). In the first trimester, an abnormal vaginal pH was not associated with preterm delivery (p = 0.3). After the first trimester, a vaginal pH of 5.0 or greater was associated with increased risk of preterm delivery (OR 9.6, 95% CI 2.0, 45.5; p = 0.001) as well as delivering an infant of less than 2500 g (OR 3.1, 95% CI 1.2, 7.8; p = 0.015). History of a previous preterm delivery was associated with increased risk of preterm delivery (OR 6.2, 95% CI 1.6, 23.7; p = 0.02). A logistic regression model used to control for a history of preterm delivery and race showed abnormal vaginal pH to remain as an independent predictor of preterm delivery (p = 0.01). Conclusions: High vaginal pH (≥ 5.0) identified women at risk for preterm delivery.     

Preterm premature rupture of membranes: risks of recurrent complications in the next pregnancy among a population-based sample of gravid women

OBJECTIVE: The purpose of this study was to ascertain the predictive value of antecedent preterm premature rupture of membranes for recurrent preterm premature rupture of membranes and preterm delivery rates in the next pregnancy compared with background rates among a population-based sample of women at a single institution. STUDY DESIGN: Records of patients with index singleton pregnancies that were complicated by preterm premature rupture of membranes whose next delivery resulted in a delivery at >or=20 weeks at the same institution were reviewed for the incidence and gestational age of recurrent preterm premature rupture of membranes and preterm delivery. All subjects were patients of physicians whose obstetric practices were based at a single institution. Background rates of preterm premature rupture of membranes and preterm delivery in this population were generated from a systematically selected comparison group composed of the two deliveries after each of the study group's second delivery. RESULTS: The rates of recurrent preterm premature rupture of membranes (16.7%) and preterm delivery (34.2%) in the 114 study group patients were substantially greater (odds ratio, 20.6; 95% CI, 4.7-90.2; and odds ratio, 3.6; 95% CI, 2.1-6.4) than noted background rates (0.96% and 12.5%) but considerably less than the recurrence rates of either preterm premature rupture of membranes or preterm delivery that were reported by others. The gestational age of preterm premature rupture of membranes in the index pregnancy affected neither the magnitude of risk nor the gestational age of recurrent preterm premature rupture of membranes or preterm delivery in the subsequent pregnancy. Stratification of outcome measures into three subgroups that were based on the gestational age of index preterm premature rupture of membranes demonstrated no significant differences in the incidence of preterm premature rupture of membranes or preterm delivery. CONCLUSION: After a pregnancy that was complicated by preterm premature rupture of membranes, the risk for recurrent preterm premature rupture of membranes is increased by 20-fold and for recurrent preterm delivery by almost 4-fold. Gestational age of antecedent preterm premature rupture of membranes is predictive of neither risk nor timing of recurrent complications. Estimates of recurrence risks appear to be moderated by limiting analysis to a population-based sample of gravid women when compared with previous studies.     

High levels of fetal cell-free DNA in maternal serum: a risk factor for spontaneous preterm delivery

OBJECTIVE: This study was conducted to determine whether there is a relationship between the concentration of fetal cell-free DNA in maternal serum and the duration of pregnancy in women who are at high risk for preterm delivery because of either preterm labor or preterm premature rupture of the membranes. STUDY DESIGN: Sera were collected and frozen from 71 women with a male fetus. Maternal serum fetal cell-free DNA concentration was measured with the use of real-time polymerase chain reaction amplification of DYS1. Fetal cell-free DNA concentrations were converted to multiples of the median. The following groups were studied: group 1: women with preterm labor and intact membranes who were delivered at > or = 36 weeks of gestation (n = 21); group 2: women with preterm labor who were delivered at <36 weeks of gestation (n = 29); and group 3: women with preterm premature rupture of the membranes in labor (n = 20) or not in labor (n = 1) who were delivered prematurely (<36 weeks of gestation). Kaplan-Meier and Cox regression analyses were used to analyze the relationship between fetal cell-free DNA concentrations and the likelihood of preterm delivery. RESULTS: A cut-off value for fetal cell-free DNA of 1.82 multiples of the median was chosen for analysis. The cumulative rate of early preterm delivery (<30 weeks of gestation) was significantly higher for women with fetal cell-free DNA concentrations of > or = 1.82 multiples of the median than those with fetal cell-free DNA concentrations below this cut-off (45% [95% CI, 36%-74%] vs 18% [95% CI, 11%-25%]; P = .008]. The cumulative rate of preterm delivery (<36 weeks of gestation) was also significantly higher at > or = 1.82 multiples of the median (73% [95% CI, 52%-93%] vs 66% [95% CI, 54%-79%]; P = .02). After adjustment for covariates, Cox analysis showed that fetal cell-free DNA at > or = 1.82 multiples of the mechanisms of disease that are associated with a mean hazard rate of delivery of 1.57 (P = .005). CONCLUSION: High concentrations of fetal cell-free DNA in maternal serum are associated with an increased risk of spontaneous preterm delivery. This observation may have implications for the understanding of the mechanisms of disease that is associated with preterm labor.     

Perinatal outcomes in women with preterm rupture of membranes between 24 and 32 weeks of gestation and a history of vaginal bleeding

OBJECTIVE: The purpose of this study was to compare perinatal outcomes among women with conservatively treated preterm premature rupture of membranes at 24 to 32 weeks of gestation in the presence or absence of vaginal bleeding. STUDY DESIGN: This is a secondary analysis of 581 women with and without vaginal bleeding within 1 week of admission with preterm premature rupture of membranes at 24 to 32 weeks of gestation who were enrolled in a multicenter trial of antibiotic therapy during conservative treatment. The main outcome was latency to delivery. Other outcome variables included clinical abruptio placentae, amnionitis, perinatal death, severe intraventricular hemorrhage, and respiratory distress syndrome. RESULTS: Outcome data were available for 581 patients (n=50 with bleeding). Latency to delivery was not affected by the presence or absence of bleeding. In general, a history of bleeding was associated with higher frequencies of subsequently diagnosed abruptio placentae (12% vs 3.5%; P=.01), perinatal death (16% vs 4.9%; P=.006), intraventricular hemorrhage (14.3% vs 5.9%; P=.03), and respiratory distress syndrome (69.4% vs 40.4%; P<.0001), when compared with those women with nonbleeding events. Women with bleeding were less likely to be black (42% vs 60%; P=.002) and had a lower mean gestational age at preterm premature rupture of membranes (27.6 vs 28.5 weeks; P=.02) when compared with white, Hispanic, and other. After an adjustment of data was made for potentially confounding factors, women with recent bleeding were more likely to be diagnosed with abruptio placentae at delivery (odds ratio, 2.8; 95% CI, 1.03-7.8; P=.04), and their infants were more likely to have respiratory distress syndrome (odds ratio, 3.1; 95% CI, 1.5-6.6; P=.004). CONCLUSION: Vaginal bleeding before preterm premature rupture of membranes is associated with increased rates of neonatal respiratory distress syndrome and abruptio placentae, but not with reduced latency to delivery.     

Maternal smoking and causes of very preterm birth

BACKGROUND: Smoking increases the risk of preterm birth. The present study was made to elucidate the relation of smoking to causes of very preterm birth. METHODS: In a case-control study on all very preterm births in two regions of Stockholm 1988-1992, prospectively collected data were extracted from antenatal and delivery records on smoking, other maternal characteristics, pregnancy complications, and causes of preterm birth. Cases were live single births with a gestational age of < or =32 weeks and 0 days, and controls were live singletons delivered at 37 weeks or later (n = 295, respectively). Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated with logistic regression. RESULTS: Compared with non-smokers, adjusted ORs of very preterm birth among moderate smokers (1-9 cigarettes per day) and heavy smokers (> or =10 cigarettes per day) were 1.4 (95% CI 0.8-2.4) and 2.9 (95% CI 1.5-5.7), respectively. Compared with non-smokers, risk of preterm labor was increased among moderate and heavy smokers [ORs 1.9 (95% CI 1.0-3.6) and 2.6 (95% CI 1.1-1.6), respectively]. These risks remained essentially unchanged in women without an identifiable cause of preterm labor ('idiopathic preterm labor'). Smoking was also associated with dose-dependent increases in risks of preterm birth due to preterm premature rupture of membranes and late pregnancy bleedings. There was no association between smoking and risk of very preterm birth caused by hypertensive diseases. CONCLUSIONS: Smoking increases the risk of very preterm birth caused by preterm labor (including idiopathic preterm labor), preterm premature rupture of membranes, and late pregnancy bleedings.     

Previous induced abortions and the risk of very preterm delivery: results of the EPIPAGE study

OBJECTIVES: To evaluate the risk of very preterm birth (22-32 weeks of gestation) associated with previous induced abortion according to the complications leading to very preterm delivery in singletons. DESIGN: Multicentre, case-control study (the French EPIPAGE study). SETTING: Regionally defined population of births in France. SAMPLE: The sample consisted of 1943 very preterm live-born singletons (< 33 weeks of gestation), 276 moderate preterm live-born singletons (33-34 weeks) and 618 unmatched full-term controls (39-40 weeks). METHODS: Data from the EPIPAGE study were analysed using polytomous logistic regression models to control for social and demographic characteristics, lifestyle habits during pregnancy and obstetric history. The main mechanisms of preterm delivery were classified as gestational hypertension, antepartum haemorrhage, fetal growth restriction, premature rupture of membranes, idiopathic preterm labor and other causes. MAIN OUTCOME MEASURES: Odds ratios for very preterm birth by gestational age and by pregnancy complications leading to preterm delivery associated with a history of induced abortion. RESULTS: Women with a history of induced abortion were at higher risk of very preterm delivery than those with no such history (OR + 1.5, 95% CI 1.1-2.0); the risk was even higher for extremely preterm deliveries (< 28 weeks). The association between previous induced abortion and very preterm delivery varied according to the main complications leading to very preterm delivery. A history of induced abortion was associated with an increased risk of premature rupture of the membranes, antepartum haemorrhage (not in association with hypertension) and idiopathic spontaneous preterm labour that occur at very small gestational ages (< 28 weeks). Conversely, no association was found between induced abortion and very preterm delivery due to hypertension. CONCLUSION: Previous induced abortion was associated with an increased risk of very preterm delivery. The strength of the association increased with decreasing gestational age.     

Vaginal Douching,Bacterial Vaginosis,and Spontaneous Preterm Birth

ObjectiveVaginal douching and bacterial vaginosis (BV) are independently associated with spontaneous preterm birth. Because the interrelationships among these variables remain unclear, we sought to examine the associations in a prospective study.MethodsWe conducted a nested case-control study within a prospectively recruited cohort of pregnant women. We prospectively collected demographic and health status data, data on pre-pregnancy vaginal douching, vaginal smears for bacterial vaginosis as defined by Nugent’s criteria, fetal fibronectin at 26 weeks of pregnancy, and placental pathology at delivery. Spontaneous preterm births before 37 weeks’ gestation were selected as cases. All spontaneous births occurring after 37 weeks were potential control subjects. To limit costs, some tests were performed only in selected control subjects.ResultsPreterm birth occurred in 207 of 5092 women (4.1%). In bivariate analysis, BV was not associated with preterm birth (OR 1.2; 95% CI 0.5 to 2.4). Vaginal douching was significantly associated with bacterial vaginosis (P < 0.05) and preterm birth (P < 0.05). On multivariate analysis, vaginal douching was no longer associated with preterm birth, buta significant association with early preterm birth < 34 weeks (OR, 6.9; 95% CI 1.7 to 28.2) and preterm birth due to preterm labour (OR 3.0; 95% CI 1.1 to 8.5) persisted after controlling for the presence of bacterial vaginosis and placental inflammation.ConclusionVaginal douching and bacterial vaginosis were not associated with spontaneous preterm birth overall. However, vaginal douching appears to be an independent and potentially modifiable risk factor for early preterm birth (32-34 weeks), although the mechanism remains unclear.     

Pregnancy outcome following a previous spontaneous abortion (miscarriage)

OBJECTIVE: To determine the pregnancy outcome following a previous spontaneous abortion (miscarriage). METHOD: A prospective cohort study was done on 300 gravida-2 patients: 200 patients (case group) whose previous pregnancy was spontaneously aborted (early abortion), and 100 patients (control group) whose previous pregnancy went to term and a live fetus was delivered. All the patients were followed until delivery, and then the pregnancy outcomes, neonatal complications and delivery routes were determined and compared between the 2 groups. Pregnancy outcomes included: maternal complications (e.g. placenta previa, placental abruption, premature rupture of the membranes, preeclampsia and eclampsia, abortion, breech presentation, preterm labor, intrauterine fetal death); neonatal complications (low birth weight, gross congenital malformations, low Apgar score at 1 min), and delivery routes (cesarean delivery or instrumental delivery, e.g. forceps or vacuum). Statistical analysis was performed using the Statistical Package for Social Science. RESULTS: Statistical analysis showed that the pregnancy complications following a previous spontaneous miscarriage were no different from those of the control group, except for abortion (16.5 vs. 11%, p < 0.003, RR = 1.15, CI 95% = 0.95-1.39), fetal deaths (1.5 vs. 0%, p < 0.004, RR = 1.51, CI 95% = 1.39-1.63), and vaginal bleeding during the first trimester (19 vs. 1%, p < 0.001, RR = 1.57, CI 95% = 1.41-1.75), which were more than those of the control group. Also, the rate of cesarean delivery (28.14 vs. 13.48%) was increased (p = 0.026, RR = 1.25, CI 95% = 1.07-1.47). Neonatal complications were not statistically significantly different in comparison with the control group. CONCLUSION: A prior spontaneous miscarriage is a risk for the next pregnancy, and the risk of abortion and intrauterine fetal death will increase. Therefore, careful prenatal care is mandatory.     

Second trimester placental location as a predictor of an adverse pregnancy outcome.

OBJECTIVE: To determine if the second trimester placental location is associated with perinatal outcomes. MATERIALS AND METHODS: Observational study of placental location and the subsequent risk of an adverse pregnancy outcome. Placental location was divided into three categories, low, high lateral and high fundal. RESULTS: There were 3336 pregnancies analyzed in this study. Low implantation sites had a greater risk of preterm labor (odds ratio (OR) 1.70, 95% confidence interval (CI) 1.38 to 2.90, P<0.001), preterm delivery (OR 1.86, 95% CI 1.36 to 2.54, P<0.001), fewer fetuses with macrosomia (OR 0.56, 95% CI 0.38 to 0.83, P=0.010) and reduced risk of postpartum hemorrhage (OR 0.56, 95% CI 0.46 to 0.95, P=0.026). High lateral implantations had a greater risk of low 1-min (OR 1.80, 95% CI 1.11 to 2.93, P=0.017) and 5-min (OR 3.49, 95% CI 1.46 to 8.36, P=0.005) Apgar scores. CONCLUSIONS: Low placental implantation was associated with an increased risk of preterm labor, preterm delivery and a reduced risk of postpartum hemorrhage, and of a macrosomic fetus. High lateral implantation was associated with low Apgar scores.     

Risk factors for preterm birth in Korea: a multicenter prospective study

Preterm birth is a major determinant of neonatal morbidity and mortality and remains one of the most serious problems in obstetrics. The aim of this study was to investigate the risk factors for preterm birth in Korean pregnant women. A total of 2,645 women were evaluated between 20 and 42 weeks' gestation at 5 centers using a prospective study design. The patient population is limited to singleton gestations. Demographic factors, socioeconomic statuses, previous and current medical histories, complications of current gestation, and drug and alcohol abuse were evaluated, and univariate and multivariate logistic regression analyses performed. Among nulliparous women, the factors that showed a significant association with preterm delivery were as follows; vaginal bleeding during pregnancy (OR 2.6, CI 1.7-4.2), and below USD 1,000 average income (OR 5.1, CI 1.9-13.5). The factors that showed a significant association with preterm delivery among multiparous women were as follows; a history of spontaneous abortion (OR 2.4, CI 1.1-5.2), and a history of preterm delivery (OR 3.5, CI 1.02-11.8). In conclusion, vaginal bleeding during pregnancy, below USD 1,000 of average income, prior spontaneous abortion, and prior preterm delivery, were positively associated with preterm birth.     

Short-term maternal and neonatal outcomes by mode of delivery. A case-controlled study

OBJECTIVE: Side-by-side comparisons of short-term maternal and neonatal outcomes for spontaneous vaginal delivery, instrumental vaginal delivery, planned caesarean section and caesarean section during labor in patients matched for clinical condition, age, and week of gestation are lacking. This case-controlled study was undertaken to evaluate short-term maternal and neonatal complications in a healthy population at term by mode of delivery. STUDY DESIGN: Four groups of healthy women, with antenatally normal singleton pregnancies at term, who underwent instrumental vaginal delivery (no. 201), spontaneous delivery (no. 402), planned caesarean section without labor (no. 402) and caesarean section in labor (no. 402) have been retrospectively selected. Outcome measures were maternal and neonatal short-term complications. Odds ratios (OR) and 95% confidence intervals (CI) were calculated. RESULTS: Maternal complications were mostly associated with forceps-assisted and vacuum-assisted instrumental deliveries (OR: 6.9; 95% CI: 2.9-16.4 and OR 3.0; 95% CI 1.1-8.8, respectively, versus spontaneous deliveries). No significant differences in overall complications were observed between spontaneous vaginal deliveries and caesarean sections, whether planned or in labor. By comparison with caesarean sections in labor, instrumental deliveries significantly increased the risk of complications (OR: 3.2; 95% CI: 1.6-6.5). Neonatal complications were also mostly correlated with forceps-assisted and vacuum-assisted instrumental deliveries (OR: 3.5; 95% CI: 1.9-6.7 and OR 3.8; 95% CI 2.0-7.4, respectively, versus spontaneous deliveries). By comparison with caesarean sections in labor, instrumental vaginal deliveries significantly increased the risk of complications (OR: 4.2; 95% CI: 2.4-7.4). CONCLUSIONS: In healthy women with antenatally normal singleton pregnancies at term, instrumental deliveries are associated with the highest rate of short-term maternal and neonatal complications.     

Unfavorable outcome in penultimate pregnancy and premature rupture of membranes in successive pregnancy.

OBJECTIVES: Previous adverse obstetric events are known to influence the outcome of the succeeding pregnancy. We tested the hypothesis that preterm premature rupture of membranes (PROM), full-term PROM, and preterm delivery without PROM relate independently to the outcome of the immediately preceding pregnancy. METHODS: In a case-control study, 345 women 15-45 years old with preterm PROM, full-term PROM, or preterm delivery without PROM were singly matched by age, race, and parity to women having full-term delivery. Information about the penultimate pregnancy, household smoking, and sociodemographic variables were obtained during face-to-face interviews. Obstetric history, infections during pregnancy, and pregnancy complications abstracted from medical records were cross-checked with patient interview data. Penultimate pregnancy outcomes included full-term delivery, premature delivery, fetal loss or miscarriage, and planned abortion. RESULTS: Women having preterm PROM or preterm delivery without PROM in the index pregnancy were, respectively, 6.34 and 21.28 times more likely than controls to have had preterm delivery in the preceding pregnancy. A preceding fetal loss or miscarriage also increased 4.39-fold the risk for preterm PROM. Exposure to cigarette smoke, urinary tract infections, and vaginal bleeding during the index pregnancy independently increased the risk for preterm PROM. Women with full-term PROM did not differ significantly from controls in the outcomes of the penultimate pregnancy. CONCLUSION: Preterm delivery in the preceding pregnancy is associated with an increased risk for preterm delivery with or without PROM.     

Risk of cesarean delivery with elective induction of labor at term in nulliparous women.

OBJECTIVE: To quantify the risk of cesarean delivery associated with elective induction of labor in nulliparous women at term. METHODS: We performed a cohort study on a major urban obstetric service that serves predominantly private obstetric practices. All term, nulliparous women with vertex, singleton gestations who labored during an 8-month period (n = 1561) were divided into three groups: spontaneous labor, elective induction, and medical induction. The risk of cesarean delivery in the induction groups was determined using stepwise logistic regression to control for potential confounding factors. RESULTS: Women experiencing spontaneous labor had a 7.8% cesarean delivery rate, whereas women undergoing elective labor induction had a 17.5% cesarean delivery rate (adjusted odds ratio [OR] 1.89; 95% confidence interval [CI] 1.12, 3.18) and women undergoing medically indicated labor induction had a 17.7% cesarean delivery rate (OR 1.69; 95% CI 1.13, 2.54). Other variables that remained significant risk factors for cesarean delivery in the model included: epidural placement at less than 4 cm dilatation (OR 4.66; 95% CI 2.25, 9.66), epidural placement after 4 cm dilatation (OR 2.18; 95% CI 1.06, 4.48), chorioamnionitis (OR 4.61; 95% CI 2.89, 7.35), birth weight greater than 4000 g (OR 2.59; 95% CI 1.69, 3.97), maternal body mass index greater than 26 kg/m2 (OR 2.36; 95% CI 1.61, 3.47), Asian race (OR 2.35; 95% CI 1.04, 5.34), and magnesium sulfate use (OR 2.18; 95% CI 1.04, 4.55). CONCLUSION: Elective induction of labor is associated with a significantly increased risk of cesarean delivery in nulliparous women. Avoiding labor induction in settings of unproved benefit may aid efforts to reduce the primary cesarean delivery rate.