Underlying mechanisms of retained placenta: Evidence from a population based cohort study

OBJECTIVE

To determine risk factors for retained placenta, and to identify supporting epidemiologic evidence for the three previously-proposed mechanisms: (i) invasive placentation, (ii) placental hypo-perfusion, and (iii) inadequate uterine contractility.

DESIGN

A retrospective population-based cohort study.

SETTING AND POPULATION

Israeli population in the southern district.

METHODS

Data were analyzed from a tertiary hospital database, between 1989 and 2014, using univariate tests and generalized estimating equation (GEE) multivariable models.

MAIN OUTCOME MEASURES

Prevalence of retained placenta.

RESULTS

The study population included 205,522 vaginal deliveries of which 4.8% (n=9870) were complicated with retained placenta. Previous intra-uterine procedures and placenta-related pregnancy complications were found to be significant risk factors for retained placenta (history of cesarean section aOR=8.82, 95%CI 8.35-9.31; history of curettage aOR=12.80, 95%CI 10.57-15.50; pre-eclampsia aOR=1.25, 95%CI 1.14-1.38; delivery of a small for gestational age neonate aOR=1.08, 95%CI 1.01-1.16; stillbirth aOR=2.34, 95%CI 1.98-2.77). During labour, the risk for retained placenta was increased in presence of arrest of dilatation (aOR=2.03, 95%CI 1.08-3.82) or arrest of descent (aOR=1.55, 95%CI 1.22-1.96). Infections of the uterine cavity during labour were also found to be strongly associated with increased risk of retained placenta (endometritis aOR=2.21, 95%CI 1.64-2.97; chorioamnionitis aOR=3.35, 95% CI 2.78-4.04).

CONCLUSIONS

Supporting epidemiologic evidence were found for all three underlying mechanisms. In addition, there is evidence to suggest that intrauterine infection and inflammation may also be a possible pathology associated with retained placenta.

TWEETABLE ABSTRACT

Risk factors for retained placenta support previously proposed mechanisms in a large cohort study.

The effects of pravastatin on the normal human placenta: Lessons from ex-vivo models

Introduction

Research in animal models and preliminary clinical studies in humans support the use of pravastatin for the prevention of preeclampsia. However, its use during pregnancy is still controversial due to limited data about its effect on the human placenta and fetus.

Methods

In the present study, human placental cotyledons were perfused in the absence or presence of pravastatin in the maternal reservoir (PraM). In addition, placental explants were treated with pravastatin for 5, 24 and 72 h under normoxia and hypoxia. We monitored the secretion of placental growth factor (PlGF), soluble fms-like tyrosine kinase-1 (sFlt-1), soluble endoglin (sEng), endothelial nitric oxide synthase (eNOS) expression and activation and the fetal vasoconstriction response to angiotensin-II.

Results

The concentrations of PlGF, sFlt-1 and sEng were not significantly altered by pravastatin in PraM cotyledons and in placental explants compared to control. Under hypoxic conditions, pravastatin decreased sFlt-1 concentrations. eNOS expression was significantly increased in PraM cotyledons but not in pravastatin-treated placental explants cultured under normoxia or hypoxia. eNOS phosphorylation was not significantly affected by pravastatin. The feto-placental vascular tone and the fetal vasoconstriction response to angiotensin-II, did not change following exposure of the maternal circulation to pravastatin.

Conclusion

We found that pravastatin does not alter the essential physiological functions of the placenta investigated in the study. The relevance of the study lays in the fact that it expands the current knowledge obtained thus far regarding the effect of the drug on the normal human placenta. This data is reassuring and important for clinicians that consider the treatment of high-risk patients with pravastatin, a treatment that exposes some normal pregnancies to the drug.

Induction of labor in twin gestation: lessons from a population based study

INTRODUCTION

The route of delivery and the role of induction of labor in twin gestations are controversial. The aim of this study was to determine the efficacy of induction of labor in twin gestations.

METHODS

This retrospective population based cohort study included 4605 twin gestations divided into following groups: 1) spontaneous parturition (n = 2937, 63.78%); 2) induction of labor (n = 653, 14.2%) and 3) elective cesarean delivery (n = 1015, 22.04%).

RESULTS

The rate of vaginal delivery in the labor induction group was 81% (529/653). In comparison to the other study groups, induction of labor in twins was independently associated with a 77% reduction in the risk of cesarean delivery (OR 0.23; 95% CI 0.18-0.31) and a 78% reduction in the risk of postpartum death for the second twin (OR 0.22; 95% CI 0.05-0.94). The rate of nulliparity, term delivery and labor dystocia was higher in the induction of labor group (p < 0.001 in all comparisons).

CONCLUSIONS

Our results suggest that induction of labor in twin gestation is successful and is independently associated with substantial reduction in the risk of cesarean delivery and postpartum death of the second twin.

Can cell proliferation of umbilical cord blood cells reflect environmental exposures?

Environmental hazards were shown to have an impact on cell proliferation (CP). We investigated CP of lymphocytes in umbilical cord blood in relation to prenatal environmental exposures in a sample of 346 Arab-Bedouin women giving birth in a local hospital. Information on subjects' addresses at pregnancy, potential household exposures and demographical status was collected in an interview during hospitalization. This population is usually featured by high rates of neonatal morbidity and multiple environmental exposures, originating from the local industrial park (IP), household hazards and frequent male smoking. A geometric mean CP ratio 2.17 (2.06; 2.29), and was high in women residing in a direction of prevailing winds from the local IP (p value = 0.094) and who gave birth during fall-winter season (p value = 0.024). Women complaining on disturbing exposure to noise had lower CP (p value = 0.015), compared to other women. CP was not indicative of neonatal morbidity. However, our findings suggest that CP of umbilical cord might be modified by environmental exposures. A long-term follow-up of the children is required to assess their developmental outcomes.

Can we find the perfect oil to protect the perineum? A randomized-controlled double-blind trial

OBJECTIVE

To determine whether perineal massage during the second stage of labor using oil enriched with vitamins, increases the chances of delivering with an intact perineum as compared to perineal massage using pure liquid wax.

METHOD

A prospective, randomized, double-blind study was conducted. Women were assigned to liquid wax (jojoba oil) versus purified formula of almond and olive oil, enriched with vitamin B1, B2, B6, E and fatty acids. The caregivers used the oils during the second stage of labor.

RESULTS

A total of 164 women undergoing vaginal delivery were recruited. No significant differences regarding perineal lacerations, number of sutures and length of suturing were noted between the two groups. Likewise, while analyzing separately nulliparous and multiparous women, no significant differences were noted. Controlling for birth weight >4000 g, using the Mantel-Haenszel technique, no association was noted between perineal lacerations and the type of oil used (weighted OR = 0.9, 95% CI 0.3-2.4; p = 0.818).

CONCLUSION

The type of the oil used during the second stage of labor for prevention of perineal tears has no effect on the integrity of the perineum. Accordingly, it seems that there is no perfect oil.

Induction of labor after a prior cesarean delivery: lessons from a population-based study

OBJECTIVES

The aims of this study were (1) to determine the success rate of induction of labor (IOL) in women with a prior cesarean section (CS) and (2) to compare the perinatal outcome of a trial of labor (TOL) in women with one prior CS who had an IOL, spontaneous onset of labor, or an elective repeated CS (ERCS).

MATERIAL AND METHODS

This study population was divided into three groups: women who had (1) ERCS (n = 1916), (2) spontaneous TOL (n = 4263), and (3) IOL (n = 1576).

RESULTS

(1) The rate of IOL in the study cohort was 20.3%; of these, 67.4% had a successful vaginal birth after cesarean (VBAC). (2) Patients in the spontaneous TOL group had a higher VBAC rate than did those who had IOL (P < 0.001). (3) The rate of uterine rupture was comparable among all study groups. And (4) a prior vaginal birth increased the likelihood of having a successful induction and a VBAC by 50%.

CONCLUSION

IOL in patients with a previous CS is successful in about two-thirds of the cases. Induction is a safe and useful tool that can serve as an alternative for ERCS and assist to reduce the rate of ERCS.

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

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 1.5-8.5)].

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.

Remote prognosis after primary cesarean delivery: the association of VBACs and recurrent cesarean deliveries with maternal morbidity

PURPOSE

To determine the effects of vaginal birth after cesarean (VBAC) versus repeated cesarean sections (RCS) after a primary cesarean section (CS), on the rate of intraoperative and postpartum maternal morbidity.

PATIENTS AND METHODS

This is a retrospective population-based cohort study. During the study period (1988-2005) there were 200,012 deliveries by 76,985 women at our medical center; 16,365 of them had a primary CS, of which 7429 women delivered a singleton infant after the primary CS, met the inclusion criteria, were included in our study, and were followed for four consecutive deliveries. Patients were divided into three study groups according to the outcome of their consecutive delivery after the primary CS: VBAC (n = 3622), elective CS (n = 1910), or an urgent CS (n = 1897). Survival analysis models were used to investigate the effect of the urgency of CS and the numbers of pregnancy predating the primary CS on peripartum complications.

RESULTS

Women who failed a trial of labor had a higher rate of uterine rupture than those who had a VBAC. Patients who delivered by CS had a higher rate of endometritis than those giving birth vaginally. The rate of cesarean hysterectomy and transfer to other departments increased significantly at the fourth consecutive surgery (P = 0.02 and P = 0.003, respectively). VBAC was associated with a 55% reduction in the risk of intrapartum complications in comparison to a planned CS (hazard ratio [HR] 0.45; 95% confidence interval [CI]: 0.22-0.89. A greater maternal parity at the time of primary CS was associated with lower intrapartum and postpartum morbidities (HR 0.44; 95% CI: 0.24-0.79; HR 0.54; 95% CI: 0.47-0.62, respectively).

CONCLUSIONS

(1) A successful VBAC is associated with a reduction in the intrapartum complications; and (2) maternal morbidity increases substantially from the fourth consecutive cesarean delivery.

Trial of labor and vaginal birth after cesarean section in patients with uterine Müllerian anomalies: a population-based study

OBJECTIVE

The aim of our study was to determine the success rate of vaginal birth after cesarean section among patients with Müllerian anomalies in comparison to the success rate of vaginal birth after cesarean section in patients with normal uterus with emphasis on the rate of uterine rupture.

STUDY DESIGN

A retrospective population-based study was designed, including all patients with a previous cesarean section that attempted vaginal birth after cesarean section during the study period. Women with known Müllerian anomalies were included in the study group. The control group consisted of women with normal uterus. The rates of vaginal birth after cesarean section, uterine rupture, maternal morbidity, and perinatal outcome were compared between the groups.

RESULTS

Of 5571 eligible patients, 165 (2.96%) had Müllerian anomalies. The rate of vaginal birth after cesarean section was significantly lower among patients with Müllerian anomalies than in patients with normal uterus, 37.6% (62/165) vs 50.7% (2740/5406), respectively (P = .0009). During the study period, there were 10 cases of uterine rupture, all in patients with normal uterus. The major indication for repeated cesarean delivery among Müllerian anomalies patients was malpresentation, 58.3% (60/103) vs 14.4% (385/2666) in patients with normal uterus (P < .001).

CONCLUSION

A trial of vaginal birth after cesarean section in patients with uterine Müllerian malformations and cephalic presentation is not associated with a higher rate of maternal morbidity and uterine rupture.

Preeclampsia in twin gestations: association with IVF treatments, parity and maternal age

OBJECTIVE

To identify maternal factors that increase the risk of preeclampsia in twin gestations and to investigate whether twins conceived by in vitro fertilization (IVF) lead to an increased risk of preeclampsia development.

MATERIALS AND METHODS

A retrospective population-based cohort study of twin deliveries was performed. Maternal characteristics and perinatal outcomes were evaluated. Patients' data were obtained from a computerized database and analyzed using SPSS statistical package.

RESULTS

During the study period there were 2628 twin deliveries, and of these 3.1% had severe preeclampsia and 6.16% mild preeclampsia. Patients with severe preeclampsia were more likely to be primiparous, and to have significantly higher frequency of chronic hypertension, gestational diabetes mellitus (GDM), IVF treatments, cesarean delivery, preterm delivery and twin discordancy than in the normotensive patients. Chronic hypertension, pirimiparity, twin discordancy and maternal age were independent risk factors for the development of preeclampsia. In a multivariate regression model including IVF treatment, parity and maternal age as risk factors for preeclampsia, women younger than 35 years that conceived following IVF treatments had an independent risk factor for the development of preeclampsia.

CONCLUSION

IVF treatments in primiparous patients and age younger than 35 years are independent risk factors for preeclampsia. Twin discordancy is an additional independent risk factor for the occurrence of preeclampsia.

Hydramnios and small for gestational age are independent risk factors for neonatal mortality and maternal morbidity

OBJECTIVE

The objective was to evaluate the contribution of hydramnios and small for gestational age (SGA) as a combined pathology to maternal and neonatal morbidity and mortality.

METHODS

The study population consisted of 192 SGA neonates with hydramnios, 5,515 SGA neonates with a normal amount of amniotic fluids, 3,714 appropriate for gestational age (AGA) neonates with polyhydramnios and 83,763 AGA neonates with a normal amount of amniotic fluid. A cross-sectional population based study was designed between the four study groups. Multiple logistic regression analysis was used to assess the contribution of these abnormalities and different risk factors to maternal and perinatal complications.

RESULTS

The combination of hydramnios/SGA was found to be an independent risk factor for perinatal mortality (OR 20.55; CI 12.6-33.4). Congenital anomalies, prolapse of cord, hydramnios, SGA and grand multiparity were also independent risk factors for perinatal mortality. Independent risk factors for neonatal complications were prolapse of umbilical cord (OR 4.13; 95% CI 1.48-11.5), hydramnios/SGA (OR 2.72; 95% CI 1.81-4.07), chronic hypertension (OR 2.45; 95% CI 1.02-5.9), congenital malformations (OR 1.93; 95% CI 1.14-3.24) and SGA (OR 1.47; 95% CI 1.07-2). Significant independent risk factors for medical interventions during labor were fetal distress (OR 198.46; 95% CI 47.27-825.27), GDM Class B-R (OR 21.22; 95% CI 2.34-192.25), GDM class A (OR 4.64; 95% CI 2.62-8.21), severe pregnancy-induced hypertension (PIH; OR 7.74; 95% CI 2.35-25.42), hydramnios (OR 1.95; 95% CI 1.3-2.91), hydramnios/SGA (OR 1.84; 95% CI 1.12-3.02) and malpresentation (OR 1.56; 95% CI 1.32-1.84).

CONCLUSION

The combination of hydramnios and SGA is an independent risk factor for perinatal mortality and maternal complications. We suggest that the growth restriction of these fetuses is responsible for the neonatal complications, while the hydramnios contributes mainly to maternal complications.

Lipopolysaccharide induces the expression of interleukin-1alpha distinctly in different compartments of term and preterm human placentae

The aim of the study was to investigate the stimulatory effect of lipopolysaccharide (LPS) on IL-lalpha production in different compartments of term and preterm placental tissues. Homogenates from amnion, chorion, and from fetal (subchorionic placental tissues, maternal decidua, and mid-placental tissue before and after perfusion of isolated placental cotyledons of 5 term placentas and 4 placentas obtained after preterm birth (28-34 W of gestation) were examined. Isolated placental cotyledons were dually perfused LPS (100 ng/kg perfused placental tissue) was perfused into the maternal side during 10 hours. Homogenates of the samples were examined by ELISA for IL-1alpha levels, and paraffin sections of the samples were stained by immunohistochemical staining, to characterize the cellular origin of placental IL-1alpha. Paired t test and ANOVA determined statistical significance. In the homogenates, there was a tendency towards higher IL-lalpha levels in all preterm placental compartments as compared to the term compartments before perfusion. A significant increase was observed only in the chorion compartment (p = 0.035). LPS had significantly increased IL-la levels only in the decidua compartment of term placentas as compared to other placental compartments (p = 0.0004), and had decreased IL-1alpha levels in the mid-placenta (p = 0.034). In preterm placentas, addition of LPS did not affect the expression levels of IL-1alpha in either fetal or maternal compartments as determined by ELISA and immunohistochemical staining. IL-la levels in the chorion compartment of preterm placenta were significantly higher as compared to term placenta. LPS affects placental tissues of term and preterm placentas differently. Also, in the term placentas, LPS affected the different compartments differently. Thus, IL-1alpha may have a key role (as a autocrine/paracrine factor) in the regulation of normal and pathological pregnancy and parturition.

Noninvasive tests to predict fetal anemia: a study comparing Doppler and ultrasound parameters

OBJECTIVE

This study was undertaken to compare test characteristics of ultrasound and Doppler parameters in the prediction of fetal anemia in alloimmunized pregnancies.

STUDY DESIGN

In a prospective cohort study, 16 nonhydropic fetuses with red blood cell alloimmunization were evaluated with ultrasound and Doppler imaging. Middle cerebral artery (MCA) peak systolic velocity, intrahepatic umbilical venous (IHUV) maximum velocity, liver length, and spleen perimeter were measured. Results before first fetal blood sampling (FBS) or delivery were analyzed. Fetal anemia was defined as hemoglobin deficit 5 SD or greater. Sensitivity and specificity were calculated.

RESULTS

Six fetuses were anemic and required intrauterine transfusion, and 10 were not severely anemic at birth. MCA Doppler imaging was the best predictor of fetal anemia (100%), followed by IHUV (83%). Sensitivity was low for spleen perimeter (66%) and liver length (33%).

CONCLUSION

Doppler evaluation of MCA peak systolic velocity is better than IHUV maximum velocity, liver, or spleen size in the prediction of fetal anemia in red blood cell alloimmunization.

Remote prognosis of primiparous women with preeclampsia

OBJECTIVE

To describe the maternal characteristics of pregnancy and perinatal outcome of primiparous women with preeclampsia, to determine the recurrence rate and to define the maternal risk factors for preeclampsia in subsequent pregnancies.

METHODS

A retrospective cohort study. Two groups of patients were defined: the study group consisted of 380 primiparous women with preeclampsia, and in a control group of 385 primiparous women without preeclampsia. The patients were followed during their consecutive deliveries. Multiple logistic regression analysis was used to determine the independent risk factors for the recurrence of preeclampsia in the second pregnancy.

RESULTS

In the study and the control group there were a total of 1207 and 1293 deliveries, respectively. Of the 380 primiparous women in study group, 305 (80%) were identified as suffering from mild preeclampsia, 64 (17%) from severe preeclampsia, 10 (2.6%) from super imposed preeclampsia and only one (0.3%) had eclampsia. Primiparous with severe preeclampsia had a significantly higher rate of preterm delivery then those with mild preeclampsia (34 versus 11% respectively, P<0.0001). In addition, the study group had significantly higher rate of perinatal mortality (3.4 versus 0.3%, P=0.013) and perinatal complications. The recurrence rate of preeclampsia was significantly higher in the study group (25% versus 1.9%, P<0.0001). When adjusted for confounding variables, gestational diabetes was strongly associated with the recurrence of preeclampsia in the second pregnancy (OR 3.72 95% CI 1.45-9.53).

CONCLUSION

Primiparous women with preeclampsia are at an increased risk for recurrence in subsequent pregnancies. Gestational diabetes in primiparous women with preeclampsia is an independent risk factor for developing preeclampsia in the second pregnancy.

Elevated concentrations of interleukin-6 in intra-amniotic infection with Ureaplasma urealyticum in asymptomatic women during genetic amniocentesis

BACKGROUND

Intra-amniotic infection is an important cause of preterm delivery and interleukin-6 (IL-6) determination was recently applied for identification of microbial invasion of the amniotic cavity. Our aim was to determine the levels of IL-6 in culture-positive amniotic fluids at genetic amniocentesis and to evaluate their significance in relation to pregnancy outcome.

METHODS

Seven culture-positive and 23 culture-negative amniotic fluids, obtained at 17-19 weeks of gestation, were analyzed for IL-6 levels by an immunoassay (ELISA). Pregnancy outcomes of all 30 women were obtained from the medical charts.

RESULTS

The mean level of IL-6 in the culture-negative amniotic fluids was 78+/-206 pg/ml. Among the seven culture-positive, high levels of IL-6 were found only in three amniotic fluids that were culture-positive for Ureaplasma urealyticum (1834, 1342 and 2832 pg/ml). Low levels of IL-6, ranging from zero to 60 pg/ml, were found in four AFs that were culture-positive for Staphylococcus epidermidis (n=3) and Bacillus Gram-positive (n= 1). Adverse pregnancy outcome occurred in the three women who had intra-amniotic infection with U. urealyticum accompanied by high levels of IL-6 (two fetal loss and one preterm delivery at 28 weeks of gestation). The four women with culture-positive but IL-6 negative amniotic fluids, had normal pregnancy outcome and term delivery. Two of the 23 women with culture-negative had preterm delivery, one with high (1000 pg/ml) and one with low (80 pg/ml) levels of IL-6.

CONCLUSION

High levels of IL-6 are suggestive of a genuine intra-amniotic infection with urea-plasmas resulting in adverse pregnancy outcome, while culture-positive amniotic fluids with normal IL-6 levels, may suggest a state of contamination.

Meconium stained amniotic fluid in preterm delivery is an independent risk factor for perinatal complications

OBJECTIVE

To determine the prevalence and clinical significance of meconium stained amniotic fluid (MSAF) in women with preterm delivery.

STUDY DESIGN

The study population consisted of consecutive patients who arrived with intact membranes and delivered preterm, singleton neonates at the Soroka Medical Center between 1 January 1985 and 31 December 1995. Only vertex presentation was included. Antepartum death was excluded from the study. Patients were classified according to the color of amniotic fluid into two groups: MSAF and clear amniotic fluid. Maternal puerperal complications were defined in our study as the presence of at least one of the next variables: clinical chorioamnionitis; major puerperal infection including endometritis, cesarean section or postpartum hemorrhage. Perinatal complications were defined in our study as: (1) intrapartum death (IPD) or postpartum death (PPD); (2) one or more of the following: 1-min Apgar score <3, 5-min Apgar score <7 or small for gestational age. Rates of perinatal complications were assessed at: (1) 24-27 weeks; (2) 28-31 weeks; (3) 32-36 weeks. Logistic regression was used to investigate the relationship of MSAF to perinatal complications and maternal morbidity in a multivariate model.

RESULTS

During the study period, a total of 96 566 deliveries occurred in our institution and 4872 (5.0%) deliveries were preterm. Among the women delivering preterm meeting eligibility criteria, 276 (5.7%) women had intrapartum MSAF. A higher rate of IPD and PPD was observed only between 32 and 36 weeks' gestation in patients with MSAF in comparison with patients with clear amniotic fluid [6.1% (14/230) vs. 2.1% (85/4045), respectively, P=0.0001]. A statistically significant higher rate of perinatal complications was found between 28 and 31 weeks' gestation, and even a higher rate was noted between 32 and 36 weeks' gestation in the MSAF group in comparison with patients with clear amniotic fluid [51% (18/35) vs. 27.2% (93/341), respectively, P=0.003; 20% (46/230) vs. 9.8% (396/4045), respectively, P=0.0004].

CONCLUSIONS

(1) MSAF is an independent risk factor for perinatal complications in preterm deliveries (OR=1.73, CI: 1.057-2.43, P=0.001; OR=2.35, CI:1.34-4.12, P=0.002, respectively). (2) MSAF was not found to be an independent risk factor for maternal morbidity.