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

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

Placenta previa and the risk of preterm delivery.

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

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.     

Association of maternal serum alpha-fetoprotein with persistent placenta previa.

OBJECTIVE: To evaluate the relationship between maternal serum alpha-fetoprotein (MSAFP) and the risk of persistent placenta previa. METHODS: We conducted a retrospective cohort study of singleton pregnancies with sonographic evidence of placenta previa at 15-20 weeks' gestation, between October 1991 and August 2000. Only pregnancies with MSAFP determination at 15-20 weeks' gestation and non-anomalous live-born infants > or =24 weeks' gestation were included. Pregnancies in which Cesarean delivery was performed for placenta previa were considered persistent; this was the primary outcome. RESULTS: Of 275 women with previa at 15-20 weeks' gestation, 33 (12%) had previa at delivery. Trend analysis revealed a greater likelihood of persistent previa with increasing MSAFP values (p=0.01). Mid-trimester MSAFP <1 multiple of the median (MoM) was associated with a decreased incidence of persistence of 4%, significantly less than the risk at > or =1 MoM (16%; p=0.01). CONCLUSIONS: There is an association between increasing MSAFP values and greater likelihood of persistent placenta previa. An MSAFP value <1 MoM is associated with a reduction in the risk of persistence of previa to delivery.     

Placenta previa is not an independent risk factor for a small for gestational age infant

Previous studies have presented conflicting evidence on the association between intrauterine growth retardation (IUGR) and placenta previa, with some groups reporting rates of IUGR as high as 16-19%. However, most of these studies failed to include a control population, included patients with other factors known to be associated with IUGR (eg, chronic hypertension, fetal anomalies, pregnancy-induced hypertension, insulin-dependent diabetes mellitus, etc), and/or did not confirm the patient's estimated gestational age. During the study period of January 1, 1980 through June 30, 1990, 54,969 deliveries occurred at the three affiliated hospitals of the Maternal-Fetal Medicine Division of the University of Connecticut Health Center. Review of the delivery records revealed 179 singleton pregnancies with documented placenta previa and without the above exclusion factors. One hundred seventy-one of these 179 study patients were compared with 171 women without placenta previa matched for confirmed gestational age, race, parity, and fetal sex. The incidence of small for gestational age (SGA) infants was 4.1% (seven of 171) in the study group and 5.8% (ten of 171) in the control group. Mean birth weights were 2559 and 2476 g, respectively. Neither difference was statistically significant. These results suggest that the prenatal diagnosis of an SGA fetus in a pregnancy complicated by placenta previa should not simply be attributed to abnormal placental implantation. Furthermore, routine ultrasonic examinations for growth in pregnancies complicated by placenta previa are not indicated.     

正常单胎及双胎妊娠妇女子宫动脉血流变化的比较

目的探讨正常单胎和双胎妊娠妇女子宫动脉血流搏动指数（ＰＩ）在孕期中的变化,并研究子宫动脉血流ＰＩ与胎盘位置的关系。方法采用Ｄｏｐｐｌｅｒ超声诊断仪,对９９例正常单胎妊娠和２４例正常双胎妊娠妇女的子宫动脉血流ＰＩ进行了检测,并同时探测胎盘的位置。结果单胎妊娠妇女的子宫动脉血流ＰＩ无论是胎盘侧或是对侧,均随孕周增加至分娩呈逐渐下降,孕２９周时子宫动脉血流ＰＩ平均值０．７８±０．１３。但双胎妊娠妇女的子宫动脉血流ＰＩ值随孕周逐渐下降至孕２７周后,则维持在一平台水平。孕２９周时子宫动脉血流ＰＩ平均值０．６７±０．１１,无论是单胎妊娠还是双胎妊娠,胎盘侧子宫动脉血流ＰＩ值均较对侧为低。结论单胎或双胎妊娠胎盘侧子宫动脉均较对侧血流丰富;且双胎妊娠时子宫动脉血流阻力较单胎为低。     

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.     

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.     

Association of maternal serum α-fetoprotein with persistent placenta previa

Objective: To evaluate the relationship between maternal serum α-fetoprotein (MSAFP) and the risk of persistent placenta previa.

Methods: We conducted a retrospective cohort study of singleton pregnancies with sonographic evidence of placenta previa at 15?–?20 weeks' gestation, between October 1991 and August 2000. Only pregnancies with MSAFP determination at 15?–?20 weeks' gestation and non-anomalous live-born infants ??24 weeks' gestation were included. Pregnancies in which Cesarean delivery was performed for placenta previa were considered persistent; this was the primary outcome.

Results: Of 275 women with previa at 15?–?20 weeks' gestation, 33 (12%) had previa at delivery. Trend analysis revealed a greater likelihood of persistent previa with increasing MSAFP values (p?=?0.01). Mid-trimester MSAFP <?1 multiple of the median (MoM) was associated with a decreased incidence of persistence of 4%, significantly less than the risk at ??1 MoM (16%; p?=?0.01).

Conclusions: There is an association between increasing MSAFP values and greater likelihood of persistent placenta previa. An MSAFP value <?1 MoM is associated with a reduction in the risk of persistence of previa to delivery.     

Peripartum hysterectomy in Taiwan

OBJECTIVE: To investigate the incidence and associated risk factors for peripartum hysterectomy in singleton pregnancies. METHODS: A retrospective cohort study of all women with singleton pregnancies admitted for delivery in 2002 taken from the National Healthcare Insurance database. Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were calculated for maternal and hospital characteristics using logistic regression. RESULTS: There were 287 peripartum hysterectomies in 214 237 singleton pregnancies (0.13%). Cesarean delivery, vaginal birth after cesarean (VBAC), and repeat cesarean delivery had higher hysterectomy rates than vaginal delivery, with adjusted ORs of 12.13 (95% CI 8.30-17.74), 5.12 (95% CI 1.19-21.92), and 3.84 (95% CI 2.52-5.86), respectively. Pregnancies complicated with placenta previa, gestational diabetes mellitus (GDM), and premature labor were associated with significantly increased risks for peripartum hysterectomy (P<0.05). CONCLUSION: Risk factors for peripartum hysterectomy included cesarean delivery, VBAC, repeat cesarean, placenta previa, GDM, and premature labor. VBAC and repeat cesarean had a similar risk.     

Risk of preterm delivery in singletons conceived by in vitro fertilization

To evaluate the preterm delivery and other obstetrics complications similar in singleton pregnancies achieved through IVF compared to spontaneous pregnancies. Retrospective case-control study included 1663 women with singleton pregnancies following IVF-ICSI (study group) and 3326 women with singleton spontaneous pregnancies (control group) who delivered between January 2015 and January 2018 at the Peking University Third Hospital. The control group matched 1:2 by age, BMI, parity, and gravidity. Maternal outcomes included preterm delivery and complications. There was significantly higher incidence of gestational diabetes, hypertensive disorders, and placenta previa in IVF-ICSI pregnancies versus controls (p?<?.05). IVF-ICSI resulted in significantly higher rate of preterm birth than in spontaneous pregnancies (p?<?.05) and the difference remained significant for deliveries that occurred before 28, 32, and 34?weeks gestation (p?<?.05). Multivariate logistic regression analysis revealed that female-factor infertility, hypertensive disorder, placenta previa, and PROM were significant prognostic factors associated with increased risk of prematurity. IVF-ICSI is associated with increased risk of obstetric complications including preterm delivery in singleton pregnancies. Female-factor infertility is an independent prognostic factor for preterm birth. This information is important for patient counseling and helps to refine the recommendation to optimize maternal health before embarking on fertility treatments.     

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.     

A case-control study of 1253 twin pregnancies from a 1982-1987 perinatal data base

In one regional perinatal network between 1982-1987, 101,506 women delivered infants greater than 500 g, of which 1253 were twin pregnancies (1.2%). This latter group was compared statistically with a 5% random sample of the singletons (N = 5119). The results showed that the women with twin pregnancies were slightly older, had a higher parity, gained more weight during the gestation, and had a heavier body weight at delivery. Twin pregnancies were complicated by increases in hypertension (odds ratio 2.5; 95% confidence interval 2.1-3.1), abruption (odds ratio 3.0; 95% confidence interval 1.9-4.7), and anemia (odds ratio 2.4; 95% confidence interval 1.9-3.0). There was no increased risk of pyelonephritis, placenta previa, or diabetes mellitus in mothers with twins. The twin pregnancies delivered earlier and the infants were smaller, had lower Apgar scores, and were at increased risk for congenital anomalies. Fetal and neonatal mortality rates were significantly increased in the twin infants; the perinatal mortality rates for twin A and twin B were 48.8 and 64.1, respectively, compared with 10.4 per 1000 births for the singleton controls. When the twin infants A and B were of similar weight, they had a similar perinatal mortality (odds ratio 1.0; 95% confidence interval 0.6-1.8). For infants less than 2500 g, twins A and B had lower fetal and neonatal mortality rates than did singletons, but twins heavier than 2500 g were at increased risk of perinatal death.     

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.     

Placenta previa: obstetric risk factors and pregnancy outcome

Objective: To determine the incidence, obstetric risk factors and perinatal outcome of placenta previa. Study design: All singleton deliveries at our institution between 1990 and 1998 complicated with placenta previa were compared with those without placenta previa. Results: Placenta previa complicated 0.38% ( n = 298) of all singleton deliveries ( n = 78 524). A back-step multiple logistic regression model found the following factors to be independently correlated with the occurrence of placenta previa: maternal age above 40 years (OR 3.1, 95% CI 2.0-4.9), infertility treatments (OR 3.1, 95% CI 1.8-5.6), a previous Cesarean section (OR 1.8, 95% CI 1.4-2.4), a history of habitual abortions (OR 1.3, 95% CI 1.3-2.7) and Jewish ethnicity (OR 1.3, 95% CI 1.1-1.8). Pregnancies complicated with placenta previa had significantly higher rates of second-trimester bleeding (OR 156.0, 95% CI 87.2-277.5), pathological presentations (OR 7.6, 95% CI 5.7-10.1), abruptio placentae (OR 13.1, 95% CI 8.2-20.7), congenital malformations (OR 2.6, 95% CI 1.5-4.2), perinatal mortality (OR 2.6, 95% CI 1.1-5.6), Cesarean delivery (OR 57.4, 95% CI 40.7-81.4), Apgar scores at 5 min lower than 7 (OR 4.4, 95% CI 2.3-8.3), placenta accreta (OR 3.6, 95% CI 1.1-9.9) postpartum hemorrhage (OR 3.8, 95% CI 1.2-10.5), postpartum anemia (OR 5.5, 95% CI 4.4-6.9) and delayed maternal and infant discharge from the hospital (OR 10.9, 95% CI 7.3-16.1) as compared to pregnancies without placenta previa. In a multivariable analysis investigating risk factors for perinatal mortality, the following were found to be independent significant factors: congenital malformations, placental abruption, pathological presentations and preterm delivery. In contrast, placenta previa and Cesarean section were found to be protective factors against the occurrence of perinatal mortality while controlling for confounders. Conclusion: Although an abnormal implantation per se was not an independent risk factor for perinatal mortality, placenta previa should be considered as a marker for possible obstetric complications. Hence, the detection of placenta previa should encourage a careful evaluation with timely delivery in order to reduce the associated maternal and perinatal complications.     

Placenta previa: obstetric risk factors and pregnancy outcome.

OBJECTIVE: To determine the incidence, obstetric risk factors and perinatal outcome of placenta previa. STUDY DESIGN: All singleton deliveries at our institution between 1990 and 1998 complicated with placenta previa were compared with those without placenta previa. RESULTS: Placenta previa complicated 0.38% (n = 298) of all singleton deliveries (n = 78 524). A back-step multiple logistic regression model found the following factors to be independently correlated with the occurrence of placenta previa: maternal age above 40 years (OR 3.1, 95% CI 2.0-4.9), infertility treatments (OR 3.1, 95% CI 1.8-5.6), a previous Cesarean section (OR 1.8, 95% CI 1.4-2.4), a history of habitual abortions (OR 1.3, 95% CI 1.3-2.7) and Jewish ethnicity (OR 1.3, 95% CI 1.1-1.8). Pregnancies complicated with placenta previa had significantly higher rates of second-trimester bleeding (OR 156.0, 95% CI 87.2-277.5), pathological presentations (OR 7.6, 95% CI 5.7-10.1), abruptio placentae (OR 13.1, 95% CI 8.2-20.7), congenital malformations (OR 2.6, 95% CI 1.5-4.2), perinatal mortality (OR 2.6, 95% CI 1.1-5.6), Cesarean delivery (OR 57.4, 95% CI 40.7-81.4), Apgar scores at 5 min lower than 7 (OR 4.4, 95% CI 2.3-8.3), placenta accreta (OR 3.6, 95% CI 1.1-9.9) postpartum hemorrhage (OR 3.8, 95% CI 1.2-10.5), postpartum anemia (OR 5.5, 95% CI 4.4-6.9) and delayed maternal and infant discharge from the hospital (OR 10.9, 95% CI 7.3-16.1) as compared to pregnancies without placenta previa. In a multivariable analysis investigating risk factors for perinatal mortality, the following were found to be independent significant factors: congenital malformations, placental abruption, pathological presentations and preterm delivery. In contrast, placenta previa and Cesarean section were found to be protective factors against the occurrence of perinatal mortality while controlling for confounders. CONCLUSION: Although an abnormal implantation per se was not an independent risk factor for perinatal mortality, placenta previa should be considered as a marker for possible obstetric complications. Hence, the detection of placenta previa should encourage a careful evaluation with timely delivery in order to reduce the associated maternal and perinatal complications.     

Maternal serum second trimester AFP and hCG in pregnancies with placenta previa

This study was undertaken to investigate the association between placenta previa and Down syndrome screening analytes-alpha-fetoprotein (AFP) and hCG-during the second trimester. Measurements of maternal serum AFP and hCG concentrations were retrospectively analysed in relation to placenta previa in a cohort of 46 consecutive singleton pregnancies affected by placenta previa from January 1993 through December 1997 at the University Hospital of Kuopio, Finland, and then compared with those in healthy singleton control pregnancies (N=9560) from the same clinic over the same period of time. Geometric means of maternal serum AFP and hCG concentrations in pregnancies with placenta previa were 1.13 and 0. 85 multiples of the median (MoM), respectively. The mean maternal age was higher in the subjects than in the controls (30.9 years compared with 28.8 years) (p<0.01). In relation to Down syndrome risk assessment, the pattern of the two markers together with maternal age indicated high risk as often in the study subjects as in the controls. Even though the maternal serum AFP and hCG differences were not statistically significant, they may be of some clinical importance, and further studies are needed to evaluate whether placental site should be taken into account in maternal serum screening.     

Obstetric outcomes in 102 pregnancies after preimplantation genetic diagnosis

OBJECTIVE: We sought to determine whether preimplantation genetic diagnosis is associated with particular pregnancy or delivery complications. STUDY DESIGN: A total of 102 consecutive pregnancies after preimplantation genetic diagnosis by polar body removal performed at Illinois Masonic Medical Center resulting in 114 live births were analyzed. All patients were given a delivery and newborn questionnaire, and attempts were made to contact and question them regarding any pregnancy complications and type of delivery. Permission was obtained to examine medical records and discuss the patient's pregnancy with her obstetrician when questions existed with respect to complications or indication for cesarean delivery. RESULTS: Delivery and newborn questionnaires were completed or telephone contact was achieved for 100 of the 102 pregnancies. There were 85 singleton, 9 twin, and 7 triplet pregnancies. Of the 7 triplet gestations, 3 couples elected multifetal pregnancy reduction to twins and healthy triplets were born to 4 couples between 32 and 36 weeks by cesarean delivery. Of the 80 singleton deliveries, 60 (75%) progressed to term. Of these 60 term singleton deliveries, 34 were vaginal, 23 were cesarean (40%), and 3 delivery types were unknown. The incidence of small-for-gestational-age infants was 3% for neonates in the 60 term singleton deliveries and 7% in the entire cohort of 80 singleton deliveries. Only 3 pregnancy complications (other than premature delivery) were reported more than once. There were 3 instances each of gestational diabetes, intrauterine growth restriction, and pregnancy-induced hypertension. There was 1 case each of HELLP (hemolysis, elevated liver enzymes, and low platelets) syndrome, congestive heart failure, mild oligohydramnios, and abruptio placentae. The indications for cesarean delivery were (in descending order) failure of labor to progress (n = 7), fetal distress (n = 4), placenta previa (n = 4), elective repeat cesarean delivery (n = 4), triplets (n = 3), uterine scarring (n = 3), 1 twin in the breech position (n = 3), failed forceps delivery (n = 2), and a variety of other indications that occurred in only 1 patient each. All preimplantation genetic diagnoses were confirmed by prenatal or postnatal testing. No diagnostic errors were made in this cohort of patients or in any patients undergoing preimplantation genetic diagnosis having polar body removal in our center. CONCLUSIONS: Preimplantation genetic diagnosis is associated with a risk of multiple gestations, cesarean delivery, and placenta previa. Cesarean delivery rates and multiple gestation rates are comparable to those of patients undergoing in vitro fertilization in general. The preimplantation genetic diagnosis itself does not seem to cause an increased risk for any particular pregnancy complication, with the possible exception of placenta previa, which was seen in 4% of patients.     

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

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