Prevalence of abnormally invasive placenta among deliveries in mainland China: A PRISMA-compliant Systematic Review and Meta-analysis

Prevalence of placenta previa among deliveries: An update systematic review and meta-analysis after the introduction of the two-child policy in Mainland China

Background

As birth policy can affect maternal and infant health, we sought to identify whether and how the introduction of the two-child policy might have affected the prevalence of placenta previa in pregnant women in mainland China.

Methods

In this update meta-analysis and systematic review, we searched PubMed, Web of Science, the Cochrane Library, Weipu, Wanfang, and the China National Knowledge Infrastructure (CNKI) databases for studies evaluating the prevalence of placenta previa in China published between the inception of each database and March 2024, with no restrictions. Two investigators independently extracted the data from each included study. We then combined the prevalence of placenta previa using random-effects models.

Results

We included 128 studies in our analysis, 48 more than in our previous review. The prevalence of placenta previa among Chinese pregnant women was 1.44% (95% confidence interval (CI) = 1.32, 1.56). After the implementation of the two-child policy, the prevalence increased significantly, from 1.25% (95% CI = 1.16, 1.34) to 4.12% (95% CI = 3.33, 4.91).

Conclusions

The prevalence of placenta previa increased significantly from the one-child policy period to the two-child policy period among mainland Chinese pregnant women, with varying trends across regions. This change requires the attention of health officials and timely adjustment of resource allocation policies.

Registration

PROSPERO: CRD42021262309.

Factors and outcomes for placental anomalies: An umbrella review of systematic reviews and meta-analyses

Background

Placental anomalies, including placenta previa (PP), placenta accreta spectrum disorders (PAS), and vase previa (VP), are associated with several adverse foetal-neonatal and maternal complications. However, there is still a lack of robust evidence on the pathogenesis and adverse outcomes of the diseases. Through this umbrella review, we aimed to systematically review existing meta-analyses exploring the factors and outcomes for pregnancy women with placental anomalies.

Methods

We searched PubMed, Embase, Web of Science, and the Cochrane Library from inception to February 2023. We used AMSTAR 2 to assess the quality of the reviews and estimated the pooled risk and 95% confidence intervals (CIs) for each meta-analysis.

Results

We included 34 meta-analyses and extracted 55 factors (27 for PP, 22 for PAS, and 6 for VP) and 16 outcomes (12 for PP, and 4 for VP) to assess their credibility. Seven factors (maternal cocaine use (for PP), uterine leiomyoma (for PP), prior abortion (spontaneous) (PP), threatened miscarriage (PP), maternal obesity (PP), maternal smoking (PAS), male foetus (PAS)) had high epidemiological evidence. Twelve factors and six outcomes had moderate epidemiological evidence. Twenty-two factors and eight outcomes showed significant association, but with weak credibility.

Conclusions

We found varying levels of evidence for placental anomalies of different factors and outcomes in this umbrella review.

Registration

PROSPERO: CRD42022300160.

Ultrasound scoring system for prenatal diagnosis of placenta accreta spectrum

BACKGROUND

To develop an ultrasound scoring system for placenta accreta spectrum (PAS), evaluate its diagnostic value, and provide a practical approach to prenatal diagnosis of PAS.

METHODS

A total of 532 pregnant women (n = 184 no PAS, n = 120 placenta accreta, n = 189 placenta increta, n = 39 placenta percreta) at high-risk for placenta accreta who delivered in the Third Affiliated Hospital of Zhengzhou University between January 2021 and December 2022 underwent prenatal ultrasound to evaluate placental invasion. An ultrasound scoring system that included placental and cervical morphology and history of cesarean section was created. Each feature was assigned a score of 0 ~ 2, according to severity. Thresholds for the total ultrasound score that discriminated between no PAS, placenta accreta, placenta increta, and placenta percreta were calculated.

RESULTS

Univariate and multivariate regression analysis identified seven indicators of PAS that were included in the ultrasound scoring system, including placental location, placental thickness, presence/absence of the retroplacental space, thickness of the retroplacental myometrium, presence/absence of placental lacunae, retroplacental myometrial blood flow and history of cesarean section. Using the final ultrasound scoring system, no PAS is diagnosed at a total score < 5, placenta accreta or placenta increta is diagnosed at a total score 5-10, and placenta percreta is diagnosed at a total score ≥ 10.

CONCLUSIONS

This study identified seven indicators of PAS and included them in an ultrasound scoring system that has good diagnostic efficacy and clinical utility.

TRIAL REGISTRATION

ChiCTR2300069261 (retrospectively registered on 10/03/2023).

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.

Intraplacental T2-hypointense bands may help predict placental invasion depth and postpartum hemorrhage in placenta accrete spectrum disorders in high-risk gravid patients

INTRODUCTION

Accurate noninvasive prenatal diagnosis of placenta accreta spectrum (PAS) disorder is critical for delivery management.

PURPOSE

To evaluate the diagnostic ability of MRI features in predicting the PAS, invasive depth and postpartum hemorrhage (PPH) in high-risk gravid patients.

MATERIALS AND METHODS

Between February 2019 and November 2020, women with ultrasound (US)-suspected PAS were enrolled. With the exclusion criteria, 80 women were included in the study. Two experienced genitourinary radiologists reviewed and recorded the MRI features. The chi square test was used to compare the effectiveness of MRI features. Relative risk ratios were computed to test the association of intraplacental T2-hypointense bands with poor outcomes of cesarean section. Receiver operating characteristic (ROC) analyses based on the number and area of intraplacental T2-hypointense bands were used to predict PAS, invasion depth, and PPH.

RESULTS

PAS was diagnosed in 56 of 80 women (70%). At delivery, 24 of 80 women (30%) experienced PPH (≥1000 mL). Intraplacental T2-hypointense bands were detected at MRI in 28 of 56 women with PAS (50%). The relative risk ratio of intraplacental T2-hypointense bands was 1.51 for PAS, 3.17 for depth of PAS invasiveness and 4.74 for PPH. The largest areas of intraplacental T2-hypointense bands for predicting PAS, invasion depth and PPH were 0.66 cm², 1.68 cm² and 1.99 cm², respectively.

DISCUSSION

The appearance of intraplacental T2-hypointense bands has important diagnostic value for PAS, its invasion depth and PPH. The area of the largest T2-hypointense band in the placenta can predict poor outcomes of cesarean section.

Role of Placenta Accreta Index for Diagnosis of Placenta Accreta Spectrum in High-Risk Patients

Background

Antenatal diagnosis of placenta accreta spectrum (PAS) can ensure multidisciplinary management at center of excellence which can reduce maternal and fetal complications. This can be established by a scoring system which provides a standardized criterion for the diagnosis and management. The objective of our study was to assess the placenta accreta index (PAI) and its individual parameters for diagnosis of PAS in high-risk patients.

Methods

A prospective study was conducted on 71 pregnant women with placenta previa and previous cesarean section. After informed consent, history was taken and ultrasonography was used to calculate the PAI for each patient. Definitive diagnosis was made clinically during cesarean section or by histopathology for those requiring hysterectomy. The data were evaluated using the latest version of Statistical Package for the Social Sciences software.

Results

All ultrasound parameters of placenta accreta index were statistically significant for predicting PAS (p value < 0.001). ROC curve with AUC of 0.87 95% CI of 0.77-0.94 showed that a score of 4.75 was the best cutoff value to diagnose PAS. Out of the 30 patients found to have placental invasion, 22 had a PAI score of more than 4.75. The score was found to have a sensitivity of 73.3%, specificity 95.1%, positive predictive value 91.7%, negative predictive value 83% and diagnostic accuracy 85.9%.

Conclusions

Women with placenta previa and history of previous CS should undergo screening by PAI, and a cutoff value of ≥ 4.75 should be viewed with high index of suspicion for the presence of PAS.

Placenta Accreta has a Low Association with Hypertensive Disease During Pregnancy: A Systematic Review Incorporating a Network Meta-analysis

A meta-analysis was performed to evaluate the potential relationship between hypertensive disease during pregnancy and placenta accreta. A systematic literature search in OVID, Embase, Cochrane Library, PubMed, and Google scholar up to May 2021 was done, and 4 studies were found including 47,353 pregnant women at the start of the study; 4283 of them had hypertensive disease during pregnancy and 493 had placenta accreta. They were reporting relationships between hypertensive disease during pregnancy and placenta accreta. The odds ratio (OR) with 95% confidence intervals (CIs) was calculated to assess the potential relationship between hypertensive disease during pregnancy and placenta accreta using the dichotomous with a random or fixed-effect model. Hypertensive disease during pregnancy was significantly related to lower prevalence of placenta accreta (OR, 0.60; 95% CI, .38-.94, p = 0.03) compared with control (no hypertensive disease during pregnancy). When looking at the result comparing the prevalence of hypertensive disease during pregnancy in women with placenta accreta compared with control (no placenta accreta), we found that the placenta accreta was significantly related to lower prevalence of hypertensive disease during pregnancy (OR, 0.59; 95% CI, 0.38-0.94, p = 0.03) compared with control. Hypertensive disease during pregnancy may have a lower prevalence of placenta accreta. Further studies are required to validate these findings.

Hypertension in pregnancy as a risk factor for placenta accreta spectrum: a systematic review incorporating a network meta-analysis

BACKGROUND

A meta-analysis was performed to evaluate the potential effects of hypertension in pregnancy on the placenta accreta spectrum.

METHODS

A systematic literature search in OVID, Embase, Cochrane Library, PubMed, and Google Scholar up to May 2021 was done, and six studies were found including 126,224 pregnant women; 7164 of them had hypertension in pregnancy and 816 had placenta accreta spectrum. They were reporting relationships between the potential effects of hypertension in pregnancy on the placenta accreta spectrum. The odds ratio (OR) with 95% confidence intervals (CIs) was calculated to assess the potential effects of hypertension in pregnancy on the placenta accreta spectrum using the dichotomous with a random- or fixed-effect model.

RESULTS

Pregnancy-induced hypertension was significantly related to lower prevalence of placenta accreta spectrum (OR 0.56; 95% CI 0.37-0.84, p = 0.005) with no heterogeneity (I² = 0%) compared to control (no hypertension in pregnancy). When looking at the result comparing the prevalence of hypertension in pregnancy in women with placenta accrete compared to control (no placenta accrete), we found that the placenta accreta spectrum was significantly related to lower prevalence of hypertension in pregnancy (OR 0.65; 95% CI 0.43-0.98, p = 0.04) compared to control.

CONCLUSIONS

Hypertension in pregnancy may have a lower prevalence of placenta accrete. Further studies are required to validate these findings.

Double-uterine-incision in the management of placenta previa complicated by placenta accreta spectrum

OBJECTIVE

To compare the effectiveness of a new double-uterine-incision, based on Ar's incision, with single-uterine-incision during cesarean section in pregnancy concurrently complicated by placenta previa and placenta accreta spectrum.

METHODS

A retrospective cohort study including 260 participants was conducted between January 2014 and June 2019. The participants only underwent Ar's incision in the single-uterine-incision group and participants underwent two uterine incisions in the new double-uterine-incision group. The demographic and clinical characteristics were compared between the two groups.

RESULTS

Fifty-six participants (21.5%) underwent a double-incision, and the other 204 underwent a single-incision. The incidence of previous cesarean delivery (91.1% vs. 68.6%) and anterior placenta (76.8% vs. 53.4%) was higher in the double-incision group. The blood loss (3400 ml vs. 1600 ml) and the need for blood transfusion (100.0% vs. 82.8%) were higher in the double-incision group. There was no significant difference between the two groups (one (1.8%) in the double-incision group and 10 (4.9%) in the single-incision group) in need for subtotal hysterectomy. After adjusting for confounding factors, there was no significant difference between the two groups concerning blood loss, blood transfusion, maternal ICU, or length of hospital stay; and the incidence of subtotal hysterectomy was lower in the double-incision group.

CONCLUSION

This new double-uterine-incision, based on Ar's incision, is an effective and valuable procedure for pregnant women with placenta previa complicated by placenta accreta spectrum, especially in women with a serious condition. It is an option for pregnant women concurrently complicated by placenta previa and placenta accreta spectrum who desire future fertility.

Development and validation of a magnetic resonance imaging-based nomogram for predicting invasive forms of placental accreta spectrum disorders

AIM

The aim of the study was to develop and validate a magnetic resonance imaging (MRI)-based nomogram for predicting invasive forms of placental accreta spectrum (PAS) disorders (placenta increta and percreta) with "uncertain ultrasound diagnosis."

METHODS

This was a retrospective cohort study of a primary cohort of 118 patients and a validation cohort of 65 patients with "uncertain ultrasound diagnosis," who were further evaluated by MRI. MRI signs associated with PAS disorders were analyzed between invasive and noninvasive groups by both univariate and logistic regression to construct the nomogram. The accuracy and discriminative ability of the nomogram were measured by concordance index (C-index) and calibration curve internally and externally.

RESULTS

The history of previous cesarean deliveries (odds ratio [OR], 3.27; 95% confidence interval [CI], 1.16-9.27), loss of double-line sign (OR, 9.49; 95% CI, 3.06-29.48), abnormal uterine bulging (OR, 4.05; 95% CI, 1.53-10.69), and disorganized abnormal placenta vascularity (OR, 3.38; 95% CI, 1.09-10.50) were imputed for the nomogram. The C-index of the nomogram was 0.85 for internal validation and 0.84 for external validation. Calibration curve showed good agreement with predicted risk and actual observation for both primary and validation cohort.

CONCLUSIONS

MRI can be a useful adjunct for clinical staging of patients with "uncertain ultrasound diagnosis."

Association between hypertensive disorders complicating pregnancy and risk of placenta accreta: a meta-analysis and systematic review

OBJECTIVE

Previous studies have reported a positive association between hypertensive disorders complicating pregnancy and placenta accreta. However, whether hypertensive disorders complicating pregnancy associated with placenta accreta is still not clear. The objective was to systematically review the literature to determine a possible association between hypertensive disorders complicating pregnancy and placenta accreta.

METHODS

A systematic search of PubMed database, the Cochrane Library, Willy Online Library, and ScienceDirect database through 1st December 2015, was conducted. Two authors independently assessed data extraction and quality of the studies using the Newcastle-Ottawa Scale. Assessment of heterogeneity and analysis of data were operated by Review Manager 5.3.0.

RESULTS

Three studies involving 4174 patients who developed hypertensive disorders complicating pregnancy of a total of 38,004 pregnant women were selected. The result of our meta-analysis revealed that pregnancy induced hypertension was significantly associated with a reduction of placenta accreta (OR = 0.50, 95% CI: 0.30-0.82; heterogeneity: I2 = 13%, p = 0.32).

CONCLUSIONS

Our meta-analysis demonstrated that the risk of placenta accreta is reduced in women with hypertensive disorders complicating pregnancy. Further well-designed studies are warranted to testify the result and explored any potential mechanism association between hypertensive disorders complicating pregnancy and placenta accreta.

Diagnostic accuracy of cystoscopy and ultrasonography in the prenatal diagnosis of abnormally invasive placenta

The aim of this study was to compare the accuracy of cystoscopy and ultrasonography for the prenatal diagnosis of abnormally invasive placenta (AIP), including its subgroups: placenta accreta (PA), placenta increta (PI), and placenta percreta (PP).A retrospective observational study including a total of 85 pregnant women at high risk for AIP underwent prenatal cystoscopy and ultrasonography evaluations. The sensitivity (Se), specificity (Sp), positive predictive value, negative predictive value, and exact diagnosed were calculated and compared for both cystoscopy and ultrasonography. Se and Sp values of cystoscopy and ultrasonography were compared by means of the McNemar test.Of the 85 patients, there were 24 (28.2%) PA, 35 (41.2%) PI, 4 (4.7%) PP, and 22 (25.9%) nonadherent placenta. The mean maternal age and gestational age of delivery were 31.88 ± 4.42 years and 36.14 ± 1.84 weeks, respectively. No one was found to develop any complications with cystoscopy like urinary tract infection, or ureteral injury or perforations. Se in the diagnosis of AIP was 50.8% with ultrasonography and 61.9% for cystoscopy. Sp was 86.4% with cystoscopy and 72.7% for ultrasonography. In subgroups, Se with cystoscopy was 25.0%, 62.9%, and 100.0% in PA, PI, and PP, respectively, and 37.5%, 74.3%, and 100.0%, respectively, for ultrasonography; Sp remained unchanged with 86.4% for cystoscopy and 72.7% for ultrasonography. After McNemar test, no difference was found in either Se or Sp between cystoscopy and ultrasonography in AIP and its subgroups.According to the depth of invasion, the diagnostic value of cystoscopy and ultrasonography is all conspicuous increased and they have similar test validity for prenatal diagnosis of AIP and its subgroups.

Prevalence of non-syndromic orofacial clefts: based on 15,094,978 Chinese perinatal infants

Non-syndromic orofacial clefts (NSOFC), which include cleft lip and palate (CLP), cleft lip only (CLO), and cleft palate only (CPO), contains a range of disorders affecting the lips and oral cavity. No systematic review and meta-analysis has been carried out to synthesize the prevalence of NSOFC in Chinese perinatal infants. We aimed to quantify and understand the variation of prevalence national and regional levels. Four English databases and four Chinese databases were searched using a comprehensive search strategy from inception to April 2017. The random effect model was used for this meta-analysis. To determine the sources of heterogeneity, subgroup analyses and meta-regression were conducted based on different categories. The protocol has been pre-registered in the PROSPERO, number CRD42017062293. 110 studies, including 15,094,978 Chinese perinatal infants, were eligible for inclusion. The pooled prevalence rate for NSOFC was 1.67‰ (95% CI 1.53–1.82), varying with provinces. The pooled prevalence estimate was 0.56‰ (0.50–0.63) for CLO, 0.82‰ (0.73–0.90) for CLP, and 0.27‰ (0.24–0.30) for CPO. Significant associations were found between overall prevalence estimates and survey year and study region. The prevalence of NSOFC was severe in Chinese perinatal infants, varying with provinces. The results will serve as a baseline for future assessment of the overall effectiveness of NSOFC control, and will also support and inform health policy for planning and helping health debates.