Anterior placental location influences onset and progress of labor and postpartum outcome

Perinatal Outcomes and Level of Labour Difficulty in Deliveries with Right and Left Foetal Position-A Preliminary Study

BACKGROUND

Many studies have shown the negative influence of the foetus's occiput posterior position during birth on the final perinatal outcome. This study aims to add to the discussion on the impact of foetus positioning on the course of labour and subjective assessment of the level of labour difficulty.

METHODS

The cross-sectional study took place from February 2020 to September 2021, and consisted of filling out observation forms and the assessment by the midwives and women of the level of labour difficulty. This study is based on the observation of 152 labours in low-risk women.

FINDINGS

When compared to left foetal positioning, labours in which the foetus was in the right position were longer and more frequently failed to progress (in 11.3% vs. 37.5%), and epidural was more frequently administrated (in 30.4% vs. 52.7%). Both women and midwives subjectively evaluated deliveries with a foetus in the right position as more difficult.

CONCLUSIONS

The right positioning of the foetus was related to greater labour difficulty and worse perinatal outcomes. The position of the foetus' head in relation to the pelvis should be considered as an indicator of the difficulty of labour and a support plan for the woman should be offered accordingly.

A Multicenter, Retrospective Comparison Study of Pregnancy Outcomes According to Placental Location in Placenta Previa

Background: We investigated the association between placental location and pregnancy outcomes in placenta previa. Methods: This multi-center retrospective study enrolled 781 women who delivered between May 1999 and February 2020. We divided the dataset into anterior (n = 209) and posterior (n = 572) groups and compared the baseline characteristics and obstetric and neonatal outcomes. The adverse obstetric outcomes associated with placenta location were evaluated using a multivariate logistic analysis. Results: Gestational age at delivery in the anterior group (253.0 ± 21.6) was significantly lower than that in the posterior group (257.6 ± 19.1) (p = 0.008). The anterior group showed significantly higher parity, rates of previous cesarean section, non-vertex fetal positions, admissions for bleeding, emergency cesarean sections, transfusions, estimated blood loss, and combined placenta accrete spectrum (p < 0.05). In the multivariate analysis, the anterior group had higher rates of transfusion (OR 2.23; 95% CI 1.50-3.30), placenta accreta spectrum (OR 2.16; 95% CI 1.21-3.97), and non-vertex fetal positions (OR 2.47; 95% CI 1.09-5.88). Conclusions: These findings suggest that more caution is required in the treatment of patients with anterior placenta previa. Therefore, if placenta previa is diagnosed prenatally, it is important to determine the location of the body and prepare for massive bleeding in the anterior group.

Effect of placenta location detected by ultrasound on the severity of placenta accreta spectrum in patients with placenta previa and placenta accreta spectrum

BACKGROUND

To evaluate the effect of placental location on the severity of placenta accreta spectrum (PAS).

METHODS

We analyzed 390 patients with placenta previa combined with placenta accreta spectrum who underwent cesarean section between January 1, 2014 and December 30, 2020 in the electronic case database of the Second Hospital of Hebei Medical University. According to the position of the placenta, 390 placentas were divided into the posterior group (n = 89), the anterior group (n = 60) and the non-central group (n = 241).

RESULTS

The history of cesarean delivery rates in the anterior group (91.67%) and the non-central group (85.71%) were statistically different from the posterior group (63.74%)(P < 0.001). Univariate logistic regression results showed that employment, urban living, gestational age, complete placenta previa, fetal presentation shoulder, gravidity, cesarean section and vaginal delivery were all predictors for the severity of placenta accreta (P < 0.05). The anterior group (P = 0.001, OR = 4.13, 95%CI: 1.84-9.24) and the non-central group (P = 0.001, OR = 2.90, 95%CI: 1.55-5.45) had a higher incidence of invasive accreta placentation than the posterior group, and were independent risk factors for invasive accreta placentation.

CONCLUSION

Compared with posterior placenta, anterior and non-central placenta are independent risk factors for invasive PAS in patients with placenta previa, during which we should be more cautious in treatment.

Risk factors for and consequences of difficult fetal extraction in emergency caesarean section. A retrospective registry-based cohort study

INTRODUCTION

This study aimed to assess risk factors for difficult fetal extraction in emergency caesarean sections, focusing on top-up epidural anesthesia compared to spinal anesthesia. Additionally, this study addressed consequences of difficult fetal extraction on neonatal and maternal morbidity.

MATERIAL AND METHODS

This retrospective registry-based cohort study included 2,332 of 2,892 emergency caesarean sections performed with local anesthesia during 2010-2017. Main outcomes were analyzed by crude and multiple adjusted logistic regression providing odds ratios.

RESULTS

Difficult fetal extraction was found in 14.9% of emergency caesarean sections. Risk-factors for difficult fetal extraction included top-up epidural anesthesia (aOR:1.37[95 %CI 1.04-1.81]), high pre-pregnancy BMI (aOR:1.41[95 %CI 1.05-1.89]), deep fetal descent (ischial spine: aOR:2.53[95 %CI 1.89-3.39], pelvic floor: aOR:3.11[95 %CI 1.32-7.33]), and anterior placental position (aOR:1.37[95 %CI 1.06-1.77]). Difficult fetal extraction was associated with increased risk of low umbilical artery pH 7.00-7.09 (aOR:3.50[95 %CI 1.98-6.15]) pH ≤ 6.99 (aOR:4.20[95 %CI 1.61-10.91]), five-minute Apgar score ≤ 6 (aOR:3.41[95 %CI 1.49-7.83]) and maternal blood loss (501-1,000 ml: aOR:1.65[95 %CI 1.27-2.16], 1,001-1,500 ml: aOR:3.24[95 %CI 2.24-4.67], 1,501-2,000 ml: aOR:3.94[95 %CI 2.24-6.94] and ≥ 2001 ml: aOR:2.76[95 %CI 1.12-6.82]).

CONCLUSION

This study identified four risk factors for difficult fetal extraction in emergency caesarean section: top-up epidural anesthesia, high maternal BMI, deep fetal descent and anterior placental position. Additionally, difficult fetal extraction was associated with poor neonatal and maternal outcomes.

Non-invasive transabdominal measurement of placental oxygenation: a step toward continuous monitoring

This study aimed to assess transabdominal placental oxygenation levels non-invasively. A wearable device was designed and tested in 12 pregnant women with an anterior placenta, 5 of whom had maternal pregnancy complications. Preliminary results revealed that the placental oxygenation level is closely related to pregnancy complications and placental pathology. Women with maternal pregnancy complications were found to have a lower placental oxygenation level (69.4% ± 6.7%) than those with uncomplicated pregnancy (75.0% ± 5.8%). This device is a step in the development of a point-of-care method designed to continuously monitor placental oxygenation and to assess maternal and fetal health.

Risk factors for non-adherent retained placenta after vaginal delivery: a systematic review

Background

Retained placenta represents a cause of maternal morbidity and mortality affecting 0.5–3% of all vaginal deliveries. The unpredictability of this condition makes difficult to develop predictive and preventive strategies to apply in clinical practice. This analysis collected and analyzed all known risk factors related to this obstetric complication.

Methods

A systematic literature review for all original research articles published between 1990 and 2020 was performed. Observational studies about retained placenta risk factors published in English language were considered eligible. Conference abstracts, untraceable articles and studies focused on morbidly adherent placenta were excluded. The included articles were screened to identify study design, number of enrolled patients and retained placenta risk factors investigated. All stages of the revision followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Statement.

Results

Thirty-five studies met the inclusion criteria. The reported retained placenta prevalence ranged from 0.5 to 4.8%. Maternal age, previous cesarean sections, previous dilation and curettage, previous retained placenta, labor induction, resulted as the most recurrent, independent risk factors for retained placenta. Previous estro-progestins therapy, morphological placental features (weight, shape, insertion of umbilical cord, implantation site), endometriosis, Assisted Reproductive Technologies, Apgar score are fascinating new proposal risk factors.

Conclusions

Old and new data are not enough robust to draw firm conclusions. Prospective and well-designed studies, based on a well agreed internationally retained placenta definition, are needed in order to clarify this potential dramatic and life-threatening condition.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-021-03721-9.

Placental location and risk of retained placenta in women with a previous cesarean section: A population-based cohort study

INTRODUCTION

Some studies have shown that women with a previous cesarean section, compared with women with a previous vaginal delivery, have an increased risk of retained placenta during a subsequent vaginal delivery. It is unknown whether this is mediated by anterior placental location, when the placenta might cover the uterine scar. The aim of this study was to evaluate whether the increased risk of retained placenta in women with a previous cesarean section is mediated by anterior placental location.

MATERIAL AND METHODS

This is a population-based cohort study, with data from the regional population-based Stockholm-Gotland Obstetric Cohort, Sweden, from 2008 to 2014. The overall study population included 49 598 women with a vaginal second delivery, where adequate information about placental location from the second-trimester ultrasound scan was available. For the main analysis, including the 3921 women with a previous cesarean section, we calculated the relative risk of retained placenta in women with an anterior placental location, using women with non-anterior placental locations as reference. Relative risks were calculated as odds ratios (OR) with 95% CI. In a second model, adjustments were made for maternal age, height, country of birth, smoking in early pregnancy, infant sex, and in vitro fertilization.

RESULTS

In the overall study population, the rate of retained placenta at the second delivery was 2.0%. The proportion of women with a retained placenta was higher among women with a previous cesarean compared with those with a previous vaginal delivery (3.4% vs 1.9%; P < .0001). In the main analysis, including women with a previous cesarean section, the risk for retained placenta was not increased with anterior compared with non-anterior placental location (OR 0.84, 95% CI 0.60-1.20). Adjustments did not affect the estimates in a significant way.

CONCLUSIONS

The increased risk of retained placenta in women with a previous cesarean section is not mediated by anterior placental location.

[Placental Locations in Subsequent Pregnancies - A Retrospective Study]

INTRODUCTION

Different locations of the placenta are associated with specific risks during pregnancy and labor. Knowledge of the placental location helps to provide better care for the expectant mother and her unborn child. Whereas multiple studies show a higher risk for a recurrent placenta previa, hardly any such data is available for any other placental location. The aim of this study was to analyze the frequency of distribution of different placental locations and to evaluate correlations between placental locations in subsequent pregnancies.

MATERIAL AND METHODS

In a retrospective cohort study women with singleton pregnancies ≥ 24 gestational weeks who had at least one ultrasound with identification of the placental location and gave birth to their firstborn and at least one more following child at our hospital between 2007 and 2016 were evaluated. Exclusion criteria were multiple pregnancies, abortions, intrauterine fetal death, and fetal malformations. Placental locations were classified into anterior, posterior, fundal, right, left, and previa.

RESULTS

Data of 1657 women were analyzed. The most frequent location was anterior, followed by posterior, fundal and lateral, and previa. Statistical analysis showed no significant correlations in subsequent pregnancies regarding placental locations.

CONCLUSION

Placental locations in subsequent pregnancies seem not to be influenced by previous pregnancies. Therefore no prognosis for placental location can be made concerning future pregnancies.

Placental location and pregnancy outcomes in nulliparous women: A population-based cohort study

INTRODUCTION

The impact of placenta previa on pregnancy, delivery and infant outcomes has been extensively studied. However, less is known about the possible association of placental location other than previa with pregnancy outcomes. The aim of this study was to investigate if placental location other than previa is associated with adverse pregnancy, delivery and infant outcomes.

MATERIAL AND METHODS

This is a population-based cohort study, with data from the regional population-based Stockholm-Gotland Obstetric Cohort, Sweden, from 2008 to 2014. The study population included 74 087 nulliparous women with singleton pregnancies resulting in live-born infants, with information about placental location from the second-trimester ultrasound screening. The association between placental location (fundal, lateral, anterior or posterior) and pregnancy outcomes was estimated using logistic regression analysis. Odds ratios (OR) with 95% confidence intervals (95% CI) were calculated, and adjustments were made for maternal age, height, country of birth, smoking in early pregnancy, sex of the infant and in vitro fertilization. Main outcome measures were pregnancy, delivery and infant outcomes.

RESULTS

Compared with posterior placental location, fundal and lateral placental locations were associated with a number of adverse pregnancy outcomes, the most important being: very preterm birth (<32 weeks of gestation) (adjusted OR [aOR] 1.78, 95% CI 1.18-2.63 and aOR 2.12, 95% CI 1.39-2.25, respectively), moderate preterm birth (32-36 weeks of gestation) (aOR 1.23, 95% CI 1.001-1.51 and aOR 1.62, 95% CI 1.32-2.00, respectively), small-for-gestational-age birth (aOR 1.67, 95% CI 1.34-2.07 and aOR 1.77, 95% CI 1.39-2.25, respectively) and manual removal of the placenta in vaginal births (aOR 3.27, 95% CI 2.68-3.99 and aOR 3.27, 95% CI 2.60-4.10, respectively). Additionally, lateral placental location was associated with preeclampsia (aOR 1.30, 95% CI 1.03-1.65) and severe postpartum hemorrhage (aOR 1.42, 95% CI 1.27-1.82).

CONCLUSIONS

Compared with posterior placental location, fundal and lateral placental locations are associated with a number of adverse pregnancy, delivery and infant outcomes.

Anterior placenta previa in the mid-trimester of pregnancy as a risk factor for neonatal respiratory distress syndrome

This study investigated whether anterior placenta previa in the second trimester is associated with neonatal respiratory distress syndrome (RDS). The neonates delivered by 2067 women between 2007 and 2015 were evaluated for the presence of RDS through birth records. The location of the placenta and the presence of placenta previa during the second and third trimesters were assessed and recorded. Demographic, prenatal, and perinatal records were reviewed. Anterior placenta previa in the second and third trimesters was correlated with RDS. Infants with lower gestational ages and birth weights had higher rates of RDS. Multivariate logistic regression analysis identified a significant association between anterior placenta previa in the second trimester and neonatal RDS. Anterior placenta previa in the second trimester is associated with neonatal RDS. Obstetricians should be aware that anterior placenta previa detected during the second trimester, irrespective of whether the placenta will migrate in the third trimester, may be an independent risk factor for neonatal RDS.

Measurement of shear wave speed dispersion in the placenta by transient elastography: A preliminary ex vivo study

Background

Placental elasticity may be modified in women with placental insufficiency. Shear wave elastography (SWE) can measure this, using acoustic radiation force, but the safety of its use in pregnant women has not yet been demonstrated. Transient elastography (TE) is a safer alternative, but has not yet been applied to the placenta. Moreover, the dispersion of shear wave speed (SWS) as a function of frequency has received relatively little study for placental tissue, although it might improve the accuracy of biomechanical assessment.

Objective

To explore the feasibility and reproducibility of TE for placental analysis, to compare the values of SWS and Young’s modulus (YM) from TE and SWE, and to analyze SWS dispersion as a function of frequency ex vivo in normal placentas.

Materials and methods

Ten normal placentas were analyzed ex vivo by an Aixplorer ultrasound system as shear waves were generated by a vibrating plate and by using an Aixplorer system.

The frequency analysis provided the value of the exponent n from a fractional rheological model applied to the TE method. We calculated intra- and interobserver agreement for SWS and YM with 95% prediction intervals, created Bland-Altman plots with 95% limits of agreement, and estimated the intraclass correlation coefficient (ICC).

Main results

The mean SWS was 1.80 m/s +/- 0.28 (standard deviation) with the TE method at 50 Hz and 1.82 m/s +/-0.13 with SWE (P = 0.912). No differences were observed between the central and peripheral regions of placentas with either TE or SWE. With TE, the intraobserver ICC for SWS was 0.68 (0.50–0.82), and the interobserver ICC for SWS 0.65 (0.37–0.85). The mean parameter n obtained from the fractional rheological model was 1.21 +/- 0.12, with variable values of n for any given SWS.

Conclusions

TE is feasible and reproducible on placentas ex vivo. The frequency analysis of SWS provides additional information about placental elasticity and appears to be able to distinguish differences between placental structures.

A prospective observational study evaluating the efficacy of prophylactic internal iliac artery balloon catheterization in the management of placenta previa-accreta: A STROBE compliant article

We studied the efficacy of prophylactic internal iliac artery balloon catheterization for managing severe hemorrhage caused by pernicious placenta previa.This prospective observational study was conducted in Tongji Hospital, Wuhan, China. One hundred sixty-three women past 32-week's gestation with placenta previa-accreta were recruited and managed. Women in the balloon group accepted prophylactic internal iliac artery balloon catheterization before scheduled caesarean delivery and controls had a conventional caesarean delivery. Intraoperative hemorrhage, transfusion volume, radiation dose, exposure time, complications, and neonatal outcomes were discussed.Significant differences were detected in estimated blood loss (1236.0 mL vs 1694.0 mL, P = .01), calculated blood loss (CBL) (813.8 mL vs 1395.0 mL, P < .001), CBL of placenta located anteriorly (650.5 mL vs 1196.0 mL, P = .03), and anterioposteriorly (928.3 mL vs 1680.0 mL, P = .02). Prophylactic balloon catheterization could reduce intraoperative red blood cell transfusion (728.0 mL vs 1205.0 mL, P = .01) and lessen usage of perioperative hemostatic methods. The incidence of hysterectomy was lower in balloon group. Mean radiation dose was 29.2 mGy and mean exposure time was 92.2 seconds. Neonatal outcomes and follow-up data did not have significant difference.Prophylactic internal iliac artery balloon catheterization is an effective method for managing severe hemorrhage caused by placenta previa-accreta as it reduced intraoperative blood loss, lessened perioperative hemostatic measures and intraoperative red cell transfusions, and reduce hysterectomies.