Second trimester uterine artery Doppler ultrasound as a screening test for adverse pregnancy outcome

One main goal of antenatal care is to improve the outcome of pregnancy in terms of perinatal morbidity and perinatal mortality by identifying women at risk of complications such as preeclampsia, intrauterine growth retardation, placental abruption and intrauterine death. The association between pre-eclampsia, intrauterine growth retardation and increased uterine artery resistance measured by Doppler ultrasound has been described and subsequently color Doppler waveform analysis of the uterine arteries has been used as a screening test for adverse pregnancy outcome. The results were conflicting and often disappointing due to differences in gestational age at the time of examination in the selected study populations and due to a lack of standardized analysis of the uterine artery waveform. In low-risk populations uterine artery Doppler waveform analysis remains a test with relatively low positive predictive values reflecting the low prevalence of pregnancy complications in an unselected population. Patients with bilateral notching at 24 weeks of gestation represent a group at risk for preeclampsia, intrauterine growth retardation and adverse pregnancy outcome.     

Combining 2nd-trimester maternal serum homocysteine levels and uterine artery Doppler for prediction of preeclampsia and isolated intrauterine growth restriction

AIM: To evaluate the efficacy of a combined 2nd-trimester maternal serum homocysteine and uterine artery Doppler screening at 20 weeks of gestation for complications of pregnancy: preeclampsia, isolated intrauterine growth restriction (IUGR), placental abruption, and stillbirths. METHODS: Consecutive singleton pregnancies without previous risk factors who had homocysteine measured as part of a serum-screening program for trisomy 21 had uterine artery Doppler performed. Sensitivity, specificity, positive and negative predictive values, odds ratio, and positive and negative likelihood ratios for the subsequent development of preeclampsia, isolated IUGR, placental abruption, stillbirth, and preterm delivery were calculated for the following methods (1) homocysteine cut-off level 6.3 micromol/l (95th centile); (2) on Doppler ultrasound bilateral notches with a mean resistance index (RI) >0.55 (50th centile), all unilateral notches with a mean RI >0.65 (80th centile), and absence of notches with a mean RI >0.7 (95th centile), and (3) Doppler ultrasound notch evaluation (bilateral, unilateral, absence as in method 2) combined with the homocysteine cut-off level of 6.3 micromol/l. RESULTS: By using a logistic regression model, methods 1 and 2 predicted preeclampsia (p < 0.001), isolated IUGR (p < 0.01), and "any complication" (p < 0.01). The sensitivity for prediction of preeclampsia using the combined method (3) was 61.3% for a false-positive rate of 2%, better than that for isolated IUGR (54%) below the 5th centile and "any complication" (56%). CONCLUSION: This prospective study confirms the potential of a combined method of elevated homocysteine and uterine artery Doppler screening for preeclampsia, isolated IUGR, and any obstetric complication.     

Screening for pre-eclampsia and small for gestational age fetuses at the 11-14 weeks scan by uterine artery Dopplers

OBJECTIVE: To assess the role of uterine artery Doppler studies at 11-14 weeks in screening for pre-eclampsia (PET), small for gestational age (SGA) fetuses, and placental abruption. METHODS: Prospective study on 1,123 women presenting for routine ultrasound examination at 11-14 weeks for nuchal translucency measurement. Uterine artery blood flow was studied by transvaginal colour Doppler, the mean pulsatility index (PI) was calculated, and the presence of a diastolic notch was recorded. RESULTS: The mean, median and 95th centile of uterine artery PI were 1.71, 1.64 and 2.54, respectively. Bilateral notches were observed in 63.4%, and a unilateral notch in 18.4% of cases. The sensitivity of mean uterine artery PI>or=95th centile for PET, early onset severe PET necessitating delivery before 34 weeks, SGA相似文献   

Prospective evaluation of uterine artery flow velocity waveforms at 12-14 and 22-24 weeks of gestation in relation to pregnancy outcome and birth weight

OBJECTIVE: Uterine artery flow velocity was prospectively assessed using Doppler ultrasound at 12-14 and 22-24 weeks of gestation in the prediction of subsequent complications related to uteroplacental insufficiency: preeclampsia, pregnancy-induced hypertension, fetal growth restriction, fetal death and placental abruption, and to elucidate its relationship with birth weight. METHODS: Uterine artery Doppler assessment was obtained during routine ultrasound screening in 263 unselected women. Flow velocity waveforms were coded according to the number of notches present at each scanning, respectively: none (0, 0), uni-/bilateral notches that disappeared (1, 0) or (2, 0), uni-/bilateral notches that persisted unilaterally (1, 1) or (2, 1), and persistent bilateral notches (2, 2). RESULTS: Complete outcome data was obtained for 243 (92.4%) women. Of these women, 55 (22.6%) and 84 (34.6%) women had uni- and bilateral notches, respectively, at 12-14 weeks' gestation; 14 (5.8%) and 21 (8.6%) patients had uni- and bilateral notches, respectively, at 22-24 weeks' gestation. Analysis of complication rates for the four groups showed that they increased with notch persistence (5.7, 13.5, 57.1 and 76.2%), while the corresponding mean birth weight declined (3,273, 3,180, 2,698 and 2,418 g). CONCLUSION: The absence or early disappearance of uterine artery notches is associated with fewer complications related to uteroplacental insufficiency and normal birth weight, whereas their late and partial disappearance or bilateral persistence tends to compromise the prognosis.     

Incidence,obstetric risk factors and pregnancy outcome of preterm placental abruption: a retrospective analysis

Objective: To determine obstetric risk factors for the occurrence of preterm placental abruption and to investigate its subsequent perinatal outcome. Study design: A retrospective comparison of all singleton preterm deliveries complicated with placental abruption, between the years 1990-1998, to all singleton preterm deliveries without placental abruption, in the Soroka University Medical Center. Results: Placental abruption complicated 300 (5.1%) of all preterm deliveries (n = 5934). A back-step multivariable analysis found the following factors to be independently correlated with the occurrence of preterm placental abruption: grandmultiparity (more than five deliveries), early gestational age, severe pregnancy-induced hypertension, previous second-trimester bleeding and non-vertex presentation. These pregnancies had a significantly lower rate of preterm premature rupture of membranes than preterm pregnancies without placental abruption. Pregnancies complicated with preterm placental abruption had significantly higher rates of cord prolapse, non-reassuring fetal heart rate patterns, congenital malformations, Cesarean deliveries, perinatal mortality, Apgar scores lower than 7 at 5 min, postpartum anemia and delayed discharge from the hospital than did preterm deliveries without placental abruption. In order to assess whether the increased risk for perinatal mortality was due to the placental abruption, or due to its significant association with other risk factors, a multivariable analysis was constructed with perinatal mortality as the outcome variable. Placental abruption (OR 3.0, 95% CI 2.1-4.1) as well as cord prolapse, previous perinatal death, low birth weight and congenital malformations were found to be independent risk factors for perinatal mortality. Conclusion: Preterm placental abruption is an unpredictable severe complication associated with significant perinatal morbidity and mortality. Factors found to be independently associated with placental abruption were grandmultiparity, severe pregnancy-induced hypertension, malpresentation, earlier gestational age and a history of second-trimester vaginal bleeding.     

Transabdominal uterine artery Doppler between 11 and 14 weeks of gestation for the prediction of outcome in high-risk pregnancies

Objective.?To assess the value of early transabdominal uterine artery Doppler ultrasound for the prediction of gestational outcomes in pregnancies at high risk for preeclampsia.

Methods.?This was an observational study. Doppler ultrasound of the uterine arteries at 11–14 weeks of gestation was performed in 76 women at high risk for preeclampsia. Abnormal uterine Doppler was defined by the presence of bilateral notching or by a mean resistance index (RI) >0.80. Adverse outcomes evaluated were preeclampsia, fetal growth restriction, placental abruption, intrauterine death, and complications requiring delivery before 34 weeks of gestation.

Results.?Among 76 women, 30 (39%) had abnormal uterine Doppler and 46 (61%) had normal Doppler waveform configuration and RI. Abnormal uterine flow was related to a significantly higher incidence of preeclampsia (17% vs. 0%; p = 0.0041), fetal growth restriction (27% vs. 0%; p = 0.0002), intrauterine death (13% vs. 0%; p = 0.0109), and iatrogenic preterm delivery (20% vs. 2%; p = 0.0086). When the Doppler was normal, the negative predictive value for complications requiring delivery before 34 weeks was 98%.

Conclusions.?Normal impedance to flow in uterine arteries between 11 and 14 weeks of gestation is strongly related to a normal pregnancy outcome in women at high risk for preeclampsia.     

胎盘疾病超声检查

超声评价胎盘包括胎盘的结构及功能。位置结构异常包括前置胎盘、血管前置、胎盘植入、胎盘早剥等。脐血流反映胎儿胎盘灌注,子宫动脉对于预测与子宫胎盘功能不良的妊娠并发症有一定的价值。     

Doppler ultrasound of the uterine artery in the prediction of severe complications during low-risk pregnancies

Aim The aim of this prospective study was to assess the role of uterine artery colour Doppler waveform analysis in the prediction of adverse pregnancy outcome such as preeclampsia, intrauterine growth retardation, placental abruption or a combination of outcome parameters.Methods Various uterine artery Doppler ultrasound parameters (RI>0.58, RI>0.7 and unilateral or bilateral notching) were tested. A second objective was to compare the predictive power of uterine artery Doppler ultrasound at 19–22 gestational weeks and 23–26 weeks gestation for an adverse pregnancy outcome.Results The mean time of delivery was 39+0 weeks of gestation. Eight newborns (2%) were delivered before 34 weeks of gestation. The mean birth weight was 3,240 g. Dystrophic fetuses (<10% percentile) were registered in 35 cases (10%). In 31 of the 346 women (9%) a cesarean section was performed because of abnormal fetal heart recording. Preeclampsia was diagnosed in 17 cases (5%). In 5 cases (1.4%) a placental abruption and 2 (0.6%) intrauterine fetal deaths were diagnosed. The sensitivity of notching for the prediction of preeclampsia was 88% and for the prediction of a severe pregnancy complication (preeclampsia and/or intrauterine growth retardation and/or intrauterine fetal death and/or placental abruption) at any gestational age was 62% with relative risks of 9.7 and 2.2, respectively. The sensitivity of notching for severe pregnancy complications requiring delivery before 34 weeks was 64% with a relative risk of 2.4. The sensitivity of notching in the uterine arteries for developing an IUGR was 56% with a relative risk of 1.7.Conclusion The predictive value of uterine artery Doppler for adverse pregnancy outcome in a low-risk population is of limited diagnostic value. Performing uterine artery Doppler studies at 23–26 weeks gestation instead of 19–22 weeks gestation increases the predictive value for adverse pregnancy outcomes.     

彩色超声对胎盘早剥的诊断及临床价值

目的:评价彩色多普勒超声(CDFI)及彩色多普勒能量超声(CDE)对胎盘早剥的诊断价值及临床意义。方法:回顾分析2000年1月至2003年12月本院收治的71例胎盘早剥声像特征及母儿结局。结果:彩色超声诊断胎盘早剥63例,符合率89%,漏误诊8例(占11%),71例胎盘早剥孕妇剖宫产63例,阴道分娩8例。活婴59例,其中早产儿家属放弃治疗1例,死胎12例伴子宫卒中3例。结论:CDE及CDFI对胎盘早剥的诊断准确率较高,能减少母儿并发症,降低围生儿死亡率,可作为胎盘早剥的首选检查方法。     

33例胎盘早剥的B超诊断

目的对产前B超检查产后证实为胎盘早剥的病例进行分析，以提高B超对胎盘早剥的确诊率。方法对我院1988年1月至2003年4月间33例胎盘早剥的声像图表现及临床资料进行回顾性分析。结果产前B超诊断胎盘早剥符合率为84．8％(28例)，其中前壁胎盘及重度胎盘早剥符合率高(93．7％，100％)，而后壁胎盘及轻度早剥无临床症状符合率低(72．77％；0)。胎盘早剥的超声图像特征为胎盘与子宫壁间为暗区、低回声，中等回声或混合回声15例，胎盘局部增厚6例，胎盘边缘或绒毛膜板下突出肿块8例(误为绒毛膜血管瘤1例)。彩色多普勤血流显像显示胎盘剥离区无血流信号。结论产前B超捡查对诊断胎盘早剥具有很重要的临床价值，为临床处理及分娩方式的选择提供了依据。     

Risk of Fetal Death Associated With Maternal Drug Dependence and Placental Abruption: A Population-Based Study

ObjectiveSubstance use in pregnancy is associated with placental abruption, but the risk of fetal death independent of abruption remains undetermined. Our objective was to examine the effect of maternal drug dependence on placental abruption and on fetal death in association with abruption and independent of it.MethodsTo examine placental abruption and fetal death, we performed a retrospective population-based study of 1 854 463 consecutive deliveries of liveborn and stillborn infants occurring between January 1, 1995 and March 31, 2001, using the Canadian Institute for Health Information Discharge Abstract Database.ResultsMaternal drug dependence was associated with a tripling of the risk of placental abruption in singleton pregnancies (adjusted odds ratio [OR] 3.1; 95% confidence intervals [CI] 2.6–3.7), but not in multiple gestations (adjusted OR 0.88; 95% CI 0.12–6.4). Maternal drug dependence was associated with an increased risk of fetal death independent of abruption (adjusted OR 1.6: 95% CI 1.1–2.2) in singleton pregnancies, but not in multiples. Risk of fetal death was increased with placental abruption in both singleton and multiple gestations, even after controlling for drug dependence adjusted OR 11.4 in singleton pregnancy; 95% CI 10.6–12.2, and 3.4 in multiple pregnancy; 95% CI 2.4–4.9).ConclusionMaternal drug use is associated with an increased risk of intrauterine fetal death independent of placental abruption. In singleton pregnancies, maternal drug dependence is associated with an increased risk of placental abruption.     

Are placental lakes of any clinical significance?

The aim of this study was to determine prospectively whether an association exists between the finding of placental lakes at the 20 week scan and an increased risk of uteroplacental complications or a poor pregnancy outcome. We studied the placental appearances in 1,198 consecutive second trimester ultrasound scans performed for routine foetal abnormality screening at our institution. The placental thickness was measured at its widest diameter in the sagittal plane and the presence or absence of placental lakes was recorded. The birth weight in each case was plotted against the centile charts in use at the hospital and recorded. Specific outcome measures included foetal growth restriction (IUGR) with a birth weight below the 5th centile, pre-eclampsia, placental abruption, and perinatal deaths. Placental lakes were seen in 17.8 per cent of the scans. There was no significant association with either maternal socio-demographic factors or perinatal mortality (OR 0.94, 95 per cent CI 0.35-2.51). No association was seen with maternal cigarette smoking (OR 1.07, 95 per cent CI 0.75-1.52), a birth weight below the 5th centile (OR 0.68, 95 per cent CI 0.39-1.18), the development of pregnancy induced hypertension (OR 0.68, 95 per cent CI 0.35-1.32), severe pre-eclampsia (OR 0.72, 95 per cent CI 0.21-2.50), or placental abruption (OR 1.79, 95 per cent CI 0.46-6.99). A finding of placental lakes was six times more likely with a thick placenta >3 cm at 20 weeks gestation (OR 6.30, 95 per cent CI 4.39 to 9.05). A finding of placental lakes during the second trimester ultrasound scan does not appear to be associated with uteroplacental complications or an adverse pregnancy outcome. The lesions are more prevalent with increasing placental thickness.     

Elevated maternal second-trimester serum alpha-fetoprotein as a risk factor for placental abruption

OBJECTIVE: To analyze the association of second-trimester maternal serum alpha-fetoprotein (MSAFP) and free beta human chorionic gonadotrophin (MSbeta-hCG) levels to placental abruption. METHODS: Fifty-seven women with placental abruption and 108 control women without placental abruption were tested for second-trimester MSAFP and MSbeta-hCG levels as a part of a trisomy 21 screening program. Discriminatory cutoff levels for MSAFP were sought to predict placental abruption. RESULTS: The median of the MSAFP multiples of median (MoM) (1.21) was significantly higher in the abruption group than in the control group (1.07) (p = 0.004). In multivariate analysis, elevated MSAFP remained an independent risk factor for placental abruption when adjusting for other risk factors (parity >/= 3, smoking, previous placental abruption, preeclampsia, bleeding in II or III trimester, and placenta previa). MSAFP >/= 1.5 MoM had a sensitivity of 29% and a false-positive rate of 10%. The levels of the MSbeta-hCG MoM did not differ between the cases and the controls. CONCLUSION: Although second-trimester MSAFP levels are higher in women with subsequent placental abruption, the clinical usefulness of this test is limited due to low sensitivity and high false-positive rate.     

Subclinical hypothyroidism and pregnancy outcomes

BACKGROUND: Clinical thyroid dysfunction has been associated with pregnancy complications such as hypertension, preterm birth, low birth weight, placental abruption, and fetal death. The relationship between subclinical hypothyroidism and pregnancy outcomes has not been well studied. We undertook this prospective thyroid screening study to evaluate pregnancy outcomes in women with elevated thyrotropin (thyroid-stimulating hormone, TSH) and normal free thyroxine levels. METHODS: All women who presented to Parkland Hospital for prenatal care between November 1, 2000, and April 14, 2003, had thyroid screening using a chemiluminescent TSH assay. Women with TSH values at or above the 97.5th percentile for gestational age at screening and with free thyroxine more than 0.680 ng/dL were retrospectively identified with subclinical hypothyroidism. Pregnancy outcomes were compared with those in pregnant women with normal TSH values between the 5th and 95th percentiles. RESULTS: A total of 25,756 women underwent thyroid screening and were delivered of a singleton infant. There were 17,298 (67%) women enrolled for prenatal care at 20 weeks of gestation or less, and 404 (2.3%) of these were considered to have subclinical hypothyroidism. Pregnancies in women with subclinical hypothyroidism were 3 times more likely to be complicated by placental abruption (relative risk 3.0, 95% confidence interval 1.1-8.2). Preterm birth, defined as delivery at or before 34 weeks of gestation, was almost 2-fold higher in women with subclinical hypothyroidism (relative risk, 1.8, 95% confidence interval 1.1-2.9). CONCLUSION: We speculate that the previously reported reduction in intelligence quotient of offspring of women with subclinical hypothyroidism may be related to the effects of prematurity. LEVEL OF EVIDENCE: II-2.     

胎盘早剥的早期临床诊断

目的探讨胎盘早剥临床漏诊的原因,提高胎盘早剥的早期诊断。方法对近5年在我院产科发生的40例胎盘早剥的临床资料进行回顾性分析。结果胎盘早剥的发生率为0.60%。19例合并妊娠高血压疾病（47.5%）,16例孕妇没有任何胎盘早剥的高危因素（40%）。大部分孕妇临床表现不典型。前壁胎盘B超诊断率高于后壁胎盘（P〈0.05）,重度胎盘早剥B超诊断率高于轻度胎盘早剥（P〈0.05）。结论识别胎盘早剥的高危因素,根据病史、临床症状和体征,结合B超以及电子胎心监护,进行综合分析判断是提高胎盘早剥诊断的有效手段。     

Complications of third-trimester amniocentesis using continuous ultrasound guidance

OBJECTIVE: The objective of the study was to estimate the risks of third-trimester amniocentesis with continuous ultrasound guidance. METHODS: Cohort study. We reviewed the medical records of women who had an amniocentesis with continuous ultrasound guidance after 30 weeks' gestation at a single institution from January 1991 through December 1994. For procedures performed from January 1991 to February 1994, we obtained information from a chart review. From March 1994 to December 1994, we collected data prospectively. The primary outcome was whether or not there were any complications within 48 hours of the procedure. We also sought to determine any risk factors associated with complications. RESULTS: Complete records and data were available for 562 amniocenteses during the study period. The mean gestational age at the time of amniocentesis was 34.9 weeks. Of the 562 procedures, five (0.8%) were unsuccessful and 50 (9%) required more than one needle stick. The complication rate was 0.7% (95% confidence level (CI) = 0.02%, 1.9%). These included spontaneous labor in a preterm gestation (1), premature rupture of the membranes (1), placental abruption (1), and fetal-maternal hemorrhage (1). No patient required an emergency cesarean delivery and none suffered a perinatal death (95% CI 0, 0.8%). Complications were not associated with the number of needle sticks, the presence of bloody amniotic fluid, or the level of operator experience. CONCLUSIONS: Third-trimester amniocentesis performed with continuous ultrasound guidance has a high success rate and low risk for complications.     

Delayed normalization of uterine artery Doppler waveforms is not a benign phenomenon

OBJECTIVE: To evaluate the pregnancy outcome in patients with abnormal uterine artery Doppler flow velocity waveforms (FVW's) at 19-21 weeks, which were subsequently normal by 24-26 weeks, and to study the effect of low-dose aspirin on these waveforms. DESIGN: The study group consisted of 49 patients who had abnormal uterine artery flow velocity waveforms (FVW's) at 19-21 weeks. These women were initially commenced on 100 mg slow-release aspirin at 20 weeks, which was discontinued at the follow-up visit, after confirming normal uterine artery Doppler FVW. The control group consisted of 730 patients with normal uterine artery Doppler waveforms at 19-21 weeks. The main outcome measures were: small for gestational age (SGA) <10th centile, pre-eclampsia, placental abruption, and perinatal mortality rate (PMR). RESULTS: When compared with the control group, the study group had an increased risk of placental abruption (2% versus 0.27%, P = 0.05) 95% Confidence Intervals CI = 0.01-0.13), low birth weight (3087 versus 3383 gm, P = 0.0003), SGA <10th centile (32.7% versus 11.9%, P 相似文献   

Evaluation of blunt abdominal trauma in the third trimester of pregnancy: maternal and fetal considerations

With the active life-style of today's pregnant women, the effects of trauma have become an important obstetric concern. A protocol was developed to monitor pregnancies complicated by major blunt abdominal trauma in the third trimester, looking specifically for delayed placental and/or fetal problems. Of the 84 pregnancies studied, the most serious complication was placental abruption. Although abruption occurred in only two cases, one case was associated with a ruptured uterus and fetal death. There were no cases of delayed abruption or delayed fetal compromise. The most common complication was preterm labor, occurring in 28% of cases when the traumatic insult happened before 37 weeks' gestation. Of these 17 patients, 15 were successfully treated with tocolysis. There were no cases of direct fetal injury or Rh-isoimmunization. A revised protocol is recommended for limited outpatient observation with nonstress testing and screening ultrasonography to rule out preterm labor and placental abruption and to document fetal well-being.     

子痫前期患者胎盘早剥发病危险因素分析

目的 探讨子痫前期患者胎盘早剥发病的危险因素.方法 对1994年1月至2008年12月的15年间,在北京大学第三医院住院并分娩的219例患者的临床资料进行回顾性分析,根据病情分为3组:子痫前期早剥组,52例,为重度子痫前期发生胎盘早剥的患者;子痫前期组,130例,为重度子痫前期未发生胎盘早剥的患者;原因不明早剥组,37例,为非子痫前期发生胎盘早剥的患者.选择同期无并发症的正常分娩产妇178例为对照组(按1∶2病例对照研究方法选择).采用单因素及多因素回归分析方法,分析子痫前期患者胎盘早剥的发病危险因素.结果 (1)与对照组比较,单因素分析结果显示,孕次、产次、子痫前期病史、中晚期妊娠丢失史、自身免疫性疾病史、慢性高血压病史、此次孕期无规律产前检查、胎儿生长受限(FGR)及脐动脉收缩期最大血流速度(S)与舒张末期血流速度(D)的比值(S/D)异常是子痫前期患者胎盘早剥发病的危险因素;多因素回归分析显示,孕期无规律产前检查(OR=45.348,95%CI为17.096～120.288,P=0.000)、FGR(OR=27.087,95%CI为5.585～131.363,P=0.000)及中晚期妊娠丢失史(OR=16.068,95% CI为1.698～152.029,P=0.015)是子痫前期患者胎盘早剥发病的独立危险因素.(2)与子痫前期组比较,子痫前期病史(OR=3.715,95% CI为1.096～12.596,P=0.035)及孕期无规律产前检查(OR=2.509,95%CI为1.173～5.370,P=0.018)是子痫前期患者胎盘早剥发病的独立危险因素.结论 孕期无规律产前检查、子痫前期病史、中晚期妊娠丢失史及FGR是影响子痫前期患者胎盘早剥发病的危险因素.     

Incidence of placental abruption in relation to cigarette smoking and hypertensive disorders during pregnancy: a meta-analysis of observational studies

OBJECTIVE: To systematically review the literature and summarize the relationship between cigarette smoking and placental abruption, and to evaluate the joint influences of smoking and hypertensive disorders (chronic hypertension and preeclampsia) on the subsequent development of abruption. DATA SOURCES: We reviewed studies identified through a MEDLINE literature search between 1966 and 1997 and through studies cited in the references of published reports. METHODS OF STUDY SELECTION: A total of 13 observational (seven case-control and six cohort) studies were identified which included a total of 1,358,083 pregnancies. We excluded case reports on placental abruption, and restricted the literature search to studies published in English. A meta-analysis was performed by computing pooled odds ratios based on random-effects models describing the association between placental abruption, smoking, and hypertensive disorders. Potential sources of heterogeneity among these studies were explored in detail. TABULATION, INTEGRATION, AND RESULTS: The overall incidence of placental abruption was 0.64% (8724 of 1,358,623). Smoking was associated with a 90% increase in the risk of placental abruption (odds ratio [OR] 1.9, 95% confidence interval [CI] 1.8, 2.0). This pattern was consistent by study design (case-control compared with cohort studies) and smoking prevalence (low compared with high prevalence, defined as less than 30% compared with 30% or more, respectively). However, the association was significantly (p < .001) stronger among the seven studies conducted outside the United States (OR 2.1, 95% CI 2.0, 2.2), compared with the six studies conducted in the United States (OR 1.6, 95% CI 1.5, 1.8). Pooled population attributable risk percentage for each stratum ranged between 15% and 25%, implying that 15-25% of placental abruption episodes are attributable to cigarette smoking. Data on the dose-response relationship between number of cigarettes smoked per day and the risk of abruption indicate that the OR increased with increasing number of cigarettes smoked. Furthermore, a meta-analysis of the joint effects of smoking and hypertension during pregnancy on the development of abruption identified two published studies, including 102,609 pregnancies. In the presence of smoking, the risk of abruption was further increased due to chronic hypertension, mild or severe preeclampsia, or chronic hypertension with superimposed preeclampsia. CONCLUSION: Our meta-analyses showed an increased risk for placental abruption in relation to both cigarette smoking and hypertensive disorders during pregnancy. Because cigarette smoking is a modifiable risk factor, and hypertensive disorders are potentially treatable if diagnosed early in pregnancy, patient education, smoking cessation programs, and early prenatal care may be important factors in the prevention of placental abruption.