Risk factors for postpartum hemorrhage requiring transfusion in cesarean deliveries for Japanese twins: comparison with those for singletons

Objective

The aim of this study was to identify the factors associated with the increased risk of postpartum hemorrhage requiring transfusion in Japanese twin pregnancies in comparison with those in Japanese singleton pregnancies.

Methods

We reviewed the obstetric records of all singleton and twin deliveries after 22?weeks’ gestation at the Japanese Red Cross Katsushika Maternity Hospital from 2003 through 2011. Potential risk factors for transfusion due to hemorrhage after cesarean delivery were selected according to previous studies of postpartum hemorrhage or transfusion or both after delivery: maternal age, parity, previous cesarean deliveries, history of infertility therapies such as in vitro fertilization, gestational age at delivery, neonatal birth weight, placenta previa, uterine myoma ≥6?cm, hypertensive disorders, placental abruption, emergency cesarean deliveries and general anesthesia.

Results

Using multiple logistic regression, the independent risk factors for postpartum hemorrhage requiring transfusion in singleton pregnancies were preterm delivery [odds ratio (OR) 2.40, 95?% confidence interval (CI) 1.2–4.6, p?<?0.01], placenta previa (OR 8.08, 95?% CI 3.9–16, p?<?0.01) and placental abruption (OR 12.8, 95?% CI 2.3–76, p?<?0.01). In twin pregnancies, however, the independent risk factors for postpartum hemorrhage requiring transfusion were gestational age at ≥41?weeks (OR 8.20, 95?% CI 1.3–40, p?<?0.01) and hypertensive disorders (OR 5.45, 95?% CI 2.2–14, p?<?0.01).

Conclusions

The factors associated with postpartum hemorrhage requiring transfusion in cesarean deliveries of twins seemed to be different from those in singleton cesarean deliveries.     

Placenta previa and the risk of preterm delivery

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

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

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

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

Neonatal outcomes with placenta previa

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

体外受精-胚胎移植后妊娠产科结局分析

目的　研究体外受精 胚胎移植 (IVF ET)术后妊娠的母儿围生期特点。方法　采用病例对照方法 ,选择行IVF ET术后妊娠并于 1993年 1月至 2 0 0 2年 12月分娩的妇女 2 5 5例 ,与同期分娩的自然受孕的妇女17175例对照 ,研究IVF ET术后妊娠的围生期情况。结果　IVF ET单胎妊娠的早产、前置胎盘、糖耐量试验(OGTT)异常、产后出血、剖宫产率高于自然受孕组 ,P <0 0 5。IVF ET双胎妊娠的分娩孕周、新生儿体重低于单胎妊娠 ,P <0 0 5 ;中度及重度妊娠期高血压疾病 (妊高征 )、胎膜早破发生率高于单胎妊娠 ,P <0 0 5。结论　IVF ET妊娠是高危妊娠 ,多胎妊娠率高是导致早产和低体重儿显著增多的主要原因 ,加强孕期保健 ,及时治疗并发症可获得良好的妊娠结局。     

Placental ratio and risk of velamentous umbilical cord insertion are increased in women with placenta previa

The purpose of this study was to explore the maternal risk profile and obstetric outcome in pregnancies affected by placenta previa. Retrospective case-control study involved all women (93 [0.37%] women with diagnosed placenta previa and 24,857 unaffected controls) who gave birth to singleton infants at Kuopio University Hospital between the years 1989 and 2000. Grand multiparity, infertility problems, and advanced maternal age were independent risk factors of placenta previa, with adjusted relative risks of 5.8, 3.7, and 2.4, respectively. Most women with placenta previa (88.2%) underwent cesarean delivery before term. They also more often had velamentous umbilical cord insertion (7.5%) and higher placental-to-birthweight ratios than the controls. Placenta previa was associated with risks of preterm delivery, low birthweight infants, and need for neonatal intensive care, at odds ratios of 27.7, 7.4, and 3.4, respectively. In conclusion, placenta previa is an infrequent pregnancy complication associated with multiparity, advanced maternal age, infertility problems, elevated placental ratio, and velamentous umbilical cord insertion.     

Perinatal outcomes in singletons following in vitro fertilization: a meta-analysis

OBJECTIVE: To estimate whether singleton pregnancies following in vitro fertilization (IVF) are at higher risk of perinatal mortality, preterm delivery, small for gestational age, and low or very low birth weight compared with spontaneous conceptions in studies that adjusted for age and parity. DATA SOURCES: We searched MEDLINE, BIOSIS, Doctoral Dissertations On-Line, bibliographies, and conference proceedings for studies from 1978-2002 using the terms "in vitro fertilization," "female infertility therapy," and "reproductive techniques" combined with "fetal death," "mortality," "fetal growth restriction," "small for gestational age," "birth weight," "premature labor," "pre-term delivery," "infant," "obstetric," "perinatal," and "neonatal." METHODS OF STUDY SELECTION: Inclusion criteria were singleton pregnancies following IVF compared with spontaneous conceptions, control for maternal age and parity; 1 of the above outcomes; and risk ratios or data to determine them. Study selection and data abstraction were performed in duplicate after removing identifying information. TABULATION, INTEGRATION, AND RESULTS: Fifteen studies comprising 12,283 IVF and 1.9 million spontaneously conceived singletons were identified. Random-effects meta-analysis was performed. Compared with spontaneous conceptions, IVF singleton pregnancies were associated with significantly higher odds of each of the perinatal outcomes examined: perinatal mortality (odds ratio [OR] 2.2; 95% confidence interval [CI] 1.6, 3.0), preterm delivery (OR 2.0; 95% CI 1.7, 2.2), low birth weight (OR 1.8; 95% CI 1.4, 2.2), very low birth weight (OR 2.7; 95% CI 2.3, 3.1), and small for gestational age (OR 1.6; 95% CI 1.3, 2.0). Statistical heterogeneity was noted only for preterm delivery and low birth weight. Sensitivity analyses revealed no significant changes in results. Early preterm delivery, spontaneous preterm delivery, placenta previa, gestational diabetes, preeclampsia, and neonatal intensive care admission were also significantly more prevalent in the IVF group. CONCLUSION: In vitro fertilization patients should be advised of the increased risk for adverse perinatal outcomes. Obstetricians should not only manage these pregnancies as high risk but also avoid iatrogenic harm caused by elective preterm labor induction or cesarean.     

Early preterm delivery due to placenta previa is an independent risk factor for a subsequent spontaneous preterm birth

ABSTRACT: BACKGROUND: To determine whether patients with placenta previa who delivered preterm have an increased risk for recurrent spontaneous preterm birth. METHODS: This retrospective population based cohort study included patients who delivered after a primary cesarean section (n = 9983). The rate of placenta previa, its recurrence, and the risk for recurrent preterm birth were determined. RESULTS: Patients who had a placenta previa at the primary CS pregnancy had an increased risk for its recurrence [crude OR of 2.65 (95 % CI 1.3-5.5)]. The rate of preterm birth in patients with placenta previa in the primary CS pregnancy was 55.9 %; and these patients had a higher rate of recurrent preterm delivery than the rest of the study population (p < .001). Among patients with placenta previa in the primary CS pregnancy, those who delivered preterm had a higher rate of recurrent spontaneous preterm birth regardless of the location of their placenta in the subsequent delivery [OR 3.09 (95 % CI 2.1-4.6)]. In comparison to all patients with who had a primary cesarean section, patients who had placenta previa and delivered preterm had an independent increased risk for recurrent preterm birth [OR of 3.6 (95 % CI 1.52-8.51)]. CONCLUSIONS: Women with placenta previa, who deliver preterm, especially before 34 weeks of gestation, are at increased risk for recurrent spontaneous preterm birth regardless to the site of placental implantation in the subsequent pregnancy. Thus, strict follow up by high risk pregnancies specialist is recommended.     

Clinical Assisted Reproduction: Are Singleton Assisted Reproductive Technology Pregnancies at Risk of Prematurity?

Purpose: Our purpose was to determine the risk of premature delivery among singleton pregnancies derived from assisted reproduction technology (ART).Methods: Ninety-five singleton ART pregnancies and 190 matched spontaneous pregnancies were assessed for preterm delivery rates, pregnancy complications, and cesarean section rates in a retrospective study at an academic medical center.Results: Among the ART singleton deliveries group (n = 95), 19 (20%) were preterm, which was statistically significantly higher than the 4% (8 of 190) found in the control group. Among the pregnancies achieved by intracytoplasmic sperm injection (ICSI) in the severe male-factor infertility subgroup (n = 22), only one preterm delivery occurred (4.5%).Conclusions: Singleton ART pregnancies are at an increased risk of preterm delivery compared to singleton pregnancies after spontaneous conception. The higher rate may be attributed to various infertility cofactors, such as uterine malformations, previous operative procedures that involved cervical dilatation, and a history of pelvic infection. This is supported by the finding that ICSI-derived pregnancies in couples with strict male-factor infertility are not at an increased risk of preterm delivery.     

Reduction of twin pregnancy to singleton: does it improve pregnancy outcome?

Objective.?To compare pregnancy complications, obstetrical and neonatal outcome of twin pregnancies reduced to singleton, with both non-reduced twin pregnancies and singleton pregnancies.

Methods.?A retrospective case–control study was performed at the Obstetrics and Gynecology Ultrasound unit of a tertiary referral medical center. Patient's population included 32 bi-chorionic bi-amniotic twin pregnancies reduced to singleton and 35 non-reduced twin pregnancies. Thirty-six patients with singleton pregnancies comprised the second control group. Main outcome measures were rates of pregnancy complications, preterm delivery (both before 37 weeks of gestation and before 34 weeks of gestation), late abortions, intra-uterine growth retardation, cesarean section, mean birth weights, and mean gestational age at delivery.

Results.?The reduced twin pregnancies group had similar rates of total pregnancy complications, preterm deliveries, and cesarean section as non-reduced twins. Gestational age at delivery and mean birth weight were also similar to non-reduced twins and significantly different compared with singletons. Preterm delivery and late abortion incidences were significantly higher when reduction was beyond 15 weeks gestation.

Conclusions.?Reduction of twin pregnancy to singleton does not change significantly pregnancy course and outcome. Favorable obstetrical and neonatal outcomes could be achieved by performing early, first trimester reductions.     

Placenta previa and the risk of preterm delivery.

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

The impact of fetal gender on preterm birth in a southern Chinese population

Objective: This study was conducted to determine whether carrying a singleton male fetus increases the risk of preterm birth (PTB) in Chinese women. Methods: A retrospective cohort study was conducted on women with singleton pregnancies and delivered in our hospital. Maternal characteristics, pregnancy outcome, and incidence of PTB, were compared between women carrying a male versus a female fetus. The independent effect of a male fetus on PTB was examined with multiple logistic regression analysis adjusting for the other confounding factors identified. Results: There were significant differences in maternal and infant characteristics between women with a male versus a female fetus. Despite similar or lower incidences of complications and labor induction, women with a male fetus had increased birth <37 weeks (7.0% versus 6.2%, p?<?0.001) and birth at 34–36 weeks (5.15% versus 4.4%, p?<?0.001), but not for birth <34 weeks (2.0% versus 1.8%, p?=?0.163). Regression analysis confirmed the association between male fetus with birth at 34–36 weeks (aOR 1.11, 95% CI 1.10–1.33) and spontaneous preterm labor (aOR 1.09, 95% CI 1.00–1.19). Conclusions: The results confirmed that carrying a male fetus is an independent risk factor for spontaneous preterm labor and PTB at 34–36 weeks gestation in southern Chinese women.     

Singleton pregnancy outcomes after assisted and non-assisted reproductive technology in infertile patients

Purpose

Singleton pregnancy after assisted reproductive technology (ART) has been associated with higher risks of adverse pregnancy outcome than naturally conceived singleton pregnancy. This study was to elucidate whether the ART procedure is responsible for abnormal pregnancy outcome comparing those after ART and non-ART in infertile patients.

Methods

We compare the singleton pregnancy outcome of infertile patients in our university hospital between 2000 and 2008 following ART (351 pregnancies) and non-ART (213 pregnancies) procedures. Pregnancy outcome parameters were incidence of pregnancy induced hypertension, placenta previa, placental abruption, cesarean delivery, preterm birth, very preterm birth, stillbirth, low birth weight and very low birth weight.

Results

Most of the pregnancy outcome parameters were not significantly different between the ART group and the non-ART group. Only placenta previa was significantly higher in the ART group than in the non-ART group (odds ratio 4.0; 95?% CI 1.2?C13.7).

Conclusions

ART procedure may itself be a risk factor for the development of placenta previa. Some of the abnormal perinatal outcomes that had been previously attributed to ART, however, may be due to the baseline characteristics of infertile patients.     

Risk factors for cerebral palsy in PPROM and preterm delivery with intact membranes*

Objective: Gestational age (GA) at delivery and spontaneous prematurity are independent risk factors for cerebral palsy (CP). The aim of this study is to investigate perinatal risk factors for CP in spontaneous preterm delivery.

Methods: A retrospective cohort study of all single pregnancies complicated by spontaneous preterm labor (PTL) or PPROM with delivery at <34 weeks from January 2006 to December 2012 was performed. We compared demographic, obstetric, neonatal, and placental histology variables in cases of spontaneous preterm birth in reference to the development of CP. Statistical analysis included chi-square, one-way ANOVA and logistic regression analysis. p?<?0.05 was considered significant.

Results: Two hundred sixty-one women were included for this study. Of 249 survivors, 5 babies died during the first year of life, 52 did not fulfill the inclusion criteria for neurologic follow-up, and 24 were lost to follow up. Thus 168 infants in the study cohort underwent neurologic follow-up. We observed 26 cases of CP. Factors related to CP were lower GA at PROM (p?=?0.007) and longer latency from PPROM to delivery (p?=?0.002) in the PPROM group, lower GA at delivery (p?<?0.001) and presence of funisitis (p?<0.001) in the PTL group.

Conclusions: GA at membrane rupture in PPROM and GA at delivery in PTL are significantly associated with CP. A process leading to neurological damage may be initiated at the moment of membranes rupture in cases of PPROM and at the time of PTL in the group with intact membranes.     

Placenta previa: neonatal death after live births in the United States

OBJECTIVE: The purpose of this study was to describe neonatal mortality rates among live births that were complicated by placenta previa in the United States. STUDY DESIGN: This was a population-based retrospective cohort study of 1997 United States singleton live births. Neonatal deaths among pregnancies that were complicated by placenta previa were compared with deaths among pregnancies with no placenta previa. Adjusted and unadjusted hazard ratios were generated from a proportional hazards regression model. RESULTS: Of 3,773,369 live births, 9656 were complicated by placenta previa (2.6 cases per 1000). Among cases of placenta previa, 114 neonatal deaths occurred (11.8 per 1000) versus 14951 (4 per 1000) among non-placenta previa neonates (P <.0001). The adjusted relative risk of death was three times higher among placenta previa neonates (hazard ratio, 3.06; 95% CI, 2.40-3.94). Placenta previa-related death was mediated through preterm delivery rather than small for gestational age. CONCLUSION: Placenta previa triples the rate of neonatal mortality, which is mediated mainly through preterm birth.     

Maternal blood endotoxin activity in pregnancies complicated by preterm premature rupture of membranes

Objective: To compare maternal blood endotoxin activity (EA) in women with preterm premature rupture of membranes (PPROM) with gestational age (GA) matched controls; to evaluate serial EA till birth in PPROM and its correlation with latency to delivery.

Methods: We followed singleton preterm pregnancies from admission with PPROM until birth. Uncomplicated, GA-matched pregnancies served as controls. Demographics, birth and neonatal outcomes were collected. EA (EAA?) was assessed serially in PPROM and at study entry in controls. EA was compared using Mann Whitney and Wilcoxon tests, p value <.05 was considered significant.

Results: We recruited 20 cases of PPROM and 20 controls. Demographics were similar between groups. Mean GA of PPROM was 29.0?±?2.2 weeks and median latency was 7.5 (IQR 14.1) weeks. Median EA at admission following PPROM was significantly elevated over controls (0.43 (0.18) versus 0.36 (0.2); p?p?=?.2) following PPROM. However, on comparing cases with latency to delivery ≤7 days (n?=?10) versus >7 days (n?=?10), there was a significant drop in EA in the latter group (0.44 (0.2) versus 0.34 (0.2); p?相似文献   

Reduced frequency of hypertensive disorders in placenta previa

The isthmic segment of the uterine artery's ascending branch has a freer course and wider diameter than distal parts of the vessel. Therefore, we assumed that this arterial segment would provide better blood flow and prevent hypoxia of the trophoblast. As a result, placenta previa pregnancies would be complicated by hypertensive disorders less often than are pregnancies with normally implanted placentas. To test this hypothesis, 491 placenta previa pregnancies, among a population of 106,866 pregnant women, were compared with pregnancies with normally implanted placentas. Clinically meaningful and statistically significant reductions in the rates and risks of hypertensive disorders were found in placenta previa pregnancies (P = .002, relative risk = 0.44, 95% confidence interval 0.25-0.78). The differences persisted when primiparous and multiparous women were examined separately and when preterm and term deliveries were separated. In a multivariate logistic regression analysis, patients with placenta previa had a third of the risk for hypertensive disorders compared with pregnant women with normally implanted placentas (relative risk = 0.36, 95% confidence interval 0.20-0.64), even after controlling for parity and preterm or term delivery. In the same model, primiparity and preterm delivery were each associated with a doubling of risk for hypertensive disorders, regardless of the placental implantation site. Thus, regardless of parity and preterm or term delivery, placenta previa and hypertensive disorders are inversely related.     

Bleeding complications in pregnancies with low-lying placenta

Objective: To evaluate pregnancy outcomes with low-lying placenta according to the distance from placenta to cervical os.

Methods: Retrospective cohort study of singleton pregnancies with low-lying placenta (placenta edge within 20?mm of internal os on transvaginal sonography) delivered at our hospital from 2002 to 2012, excluding suspected placenta accreta and vasa previa. Vaginal delivery was offered in the absence of another indication for cesarean. Outcomes were stratified according to placenta-os distance ≤10?mm and 11–20?mm.

Results: Of 98 pregnancies with low-lying placenta, 41% had placenta-os distance ≤10?mm and 59% placenta-os distance 11–20?mm. Fifty-four percent had a trial of labor. Six (15%) with placenta-os ≤10?mm and 21 (36%) with placenta-os 11–20?mm delivered vaginally, p?=?0.02. Bleeding necessitating cesarean occurred in 25%, and postpartum hemorrhage in 43%; neither complication associated with placenta-os distance. Third-trimester bleeding prior to delivery hospitalization was reported in 44% and associated with later bleeding requiring cesarean in 51% versus 4% of those without third-trimester bleeding, p?<?0.001.

Conclusion: Whereas low-lying placenta does not contraindicate labor, we found significant risk for bleeding complications, regardless of the planned mode of delivery. Placenta-os distance did not significantly affect outcomes in our series.     

Trends in primeval β-hCG level increment after fresh and frozen-thawed IVF embryo transfer cycles

Mid-trimester beta-human chorionic gonadotropin (BHCG) levels are considerably higher in pregnancies resulting from frozen embryo transfer (FET) compared with fresh (FRET), leading to a higher false positive rate in aneuploidy screening tests. We aimed to investigate the dynamics of BHCG increment and its predictive value for cycle outcome. A retrospective analysis of FRET and FET cycles. BHCG values on days 14 and 16 post embryo transfer were compared and stratified according to the number of sacs demonstrated on US scan at six weeks gestation, and pregnancy outcome (biochemical pregnancy, ectopic pregnancy, spontaneous abortion, and a singleton or twin birth). A prediction model for live birth was built. A total of 430 treatment cycles were analyzed. The average BHCG levels were significantly higher in FET compared with FRET group in nonviable pregnancies on day 14, 450 vs. 183?IU/L, p?<?.05 and day 16, 348 vs. 735?IU/L, p?<?.05, respectively. The increment of BHCG was significantly steeper in the FET compared with FRET group in biochemical pregnancies (F?=?6.485, p?=?.012*). Optimal cutoff level for live birth prediction in the FRET group was 211?IU/L (sensitivity 84%, specificity 76.2%) for day 14 and 440?IU/L (sensitivity 86.0% and specificity 72.5%) for day 16. The increment in BHCG differed significantly between the FRET and FET cycles in nonviable pregnancies. Nevertheless, the difference in BHCG levels observed in the second trimester in pregnancies conceived after FRET and FET cycle may begin as early as the fourth week of pregnancy.     

The role of shear wave elastography in the assessment of placenta previa–accreta

Objective: To evaluate the value of shear wave elastography (SWE) in the prediction of morbidly adherent placenta.

Methods: Forty-three women with normal placental location and 26 women with anteriorly localized placenta previa were recruited for this case-control study. Placental elasticity values in both the groups were determined by SWE imaging.

Results: SWE values were higher in the placenta previa group in all regions than in normal localized placentas (p?p?>?.05).

Conclusions: Placental stiffness is significantly higher in placenta previa than normal localized placentas. However, we could not demonstrate any statistically significant difference in the elasticity values between the placenta previa with and without accreta.     

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

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