The risk factors associated with placenta previa: An umbrella review

Placenta Previa

Placenta previa is an important and potentially life-threatening cause of bleeding. Historically, it was a major contributor to maternal mortality until advancements in obstetric care, including prenatal ultrasound, cesarean delivery, and transfusion medicine, drastically improved outcomes. Today, placenta previa is typically identified during routine second-trimester ultrasound, with the overwhelming majority of cases resolving before term. Key risk factors include prior cesarean delivery, advanced maternal age, and smoking. When placenta previa is diagnosed, it is essential to assess for associated conditions like placenta accreta and vasa previa. A planned cesarean delivery is recommended in cases that persist into the late third trimester.

The role of maternal blood elabela levels in the prediction of placenta previa and accreta

INTRODUCTION

Placenta previa and Placenta Accreta Spectrum are life-threatening obstetric conditions that are challenging to diagnose accurately. Currently, there is no biochemical parameter available for their diagnosis. The aim of our study is to investigate the potential of Elabela as a laboratory marker that could predict placenta previa and placenta accreta, both of which can lead to severe, life-threatening complications for the mother.

METHODS

In this study, which was conducted prospectively in two tertiary centers between 2020 and 2022, Elabela levels were examined in patient groups with placental insertion and invasion anomalies. SPSS program was used for comparative statistical analysis between groups.

RESULTS

Of the 67 analyzed patients, 32 were in the control group, 12 were in the previa group, and 23 were in the accreta group. There was no statistically significant difference between the groups regarding age, BMI, number of curettages, presence of previous cesarean section, and smoking status. The Elabela level was measured at 135.6 ± 72.1 in the control group, 988.3 ± 925.5 in the previa group, and 376 ± 364.6 in the accreta group, with a statistically significant difference between the groups. The cut-off value of Elabela levels in the previa group was determined to be 304, with a sensitivity of 83.30 % and a specificity of 83.60 % (AUC = 0.909). In the accreta group, the cut-off value was 195.5, with a sensitivity of 60.90 % and a specificity of 61.40 % (AUC = 0.658).

DISCUSSION

By showing that the prediction of placenta previa and placenta acreata can be made with a biochemical parameter in our study, young researchers will focus more on this subject and thus make many contributions to science.

Abnormal microRNA expression profile at early stages of gestation in pregnancies destined to develop placenta previa

Background

Placenta previa is the abnormal implantation of the placenta into the lower segment of the uterus, is associated with adverse maternal and fetal outcomes such as placenta accreta spectrum disorders, antepartum and postpartum hemorrhage, fetal growth restriction, prematurity, stillbirth and neonatal death, thrombophlebitis, and septicemia. The aim of the study was to assess retrospectively how the later onset of placenta previa affects the microRNA expression profile in the whole peripheral blood during the first trimester of gestation.

Methods

Regarding the occurrence of the association between aberrant microRNA expression profiles at early stages of gestation and later onset of various pregnancy-related complications, we selected for the study pregnancies developing placenta previa as the only pregnancy-related disorder. In total, 24 singleton pregnancies diagnosed with placenta previa that underwent first-trimester prenatal screening and delivered on-site within the period November 2012-May 2018 were included in the study. Overall, 80 normal pregnancies that delivered appropriate-for-gestational age newborns after completing 37 weeks of gestation were selected as the control group based on the equality of the length of biological sample storage.

Results

Downregulation of multiple microRNAs (miR-20b-5p, miR-24-3p, miR-26a-5p, miR-92a-3p, miR-103a-3p, miR-130b-3p, miR-133a-3p, miR-145-5p, miR-146a-5p, miR-155-5p, miR-181a-5p, miR-195-5p, miR-210-3p, miR-342-3p, and miR-574-3p) was observed in pregnancies destined to develop placenta previa. The combination of seven microRNAs (miR-130b-3p, miR-145-5p, miR-155-5p, miR-181a-5p, miR-210-3p, miR-342-3p, and miR-574-3p) showed the highest accuracy (AUC 0.937, p < 0.001, 100.0% sensitivity, 83.75% specificity) to differentiate, at early stages of gestation, between pregnancies with a normal course of gestation and those with placenta previa diagnosed in the second half of pregnancy. Overall, 75% of pregnancies destined to develop placenta previa were correctly identified at 10.0% FPR.

Conclusion

Consecutive large-scale analyses must be performed to verify the reliability of the proposed novel early predictive model for placenta previa occurring as the only pregnancy-related disorder.

P-glycoprotein expression is decreased in placenta accreta and placenta previa disorders

BACKGROUND

P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) are multidrug resistance (MDR) transporters that function as placental gatekeepers, lowering the fetal levels of diverse xenobiotics and toxins that may be circulating in the maternal blood throughout pregnancy. Placenta accreta spectrum (PAS) and the placenta previa (PP) disorders are obstetric pathologies encompassed by an abnormal invasion of chorionic villous tissue in the uterine wall or at the endocervical os, respectively. Given the fact that MDR transporters are involved in placentation and are highly responsive to inflammation, we hypothesized that immunostaining of P-gp and BCRP would be altered in PAS and in PP specimens.

METHODS

A total of 32 placental histological specimens, sorted in control (N.=8; physiological pregnancies), PAS (N.=14), and PP (N.=10), were subjected to immunohistochemistry for P-gp and BCRP transporters. Semi-quantitative scoring of the resulting immunostained area and intensity was undertaken.

RESULTS

Decreased P-gp staining intensity in the syncytiotrophoblast of the PAS compared to the control group (P<0.05) and in the PP compared to the PAS group was detected (P<0.05). Fetal blood vessel P-gp immunostaining was decreased in PAS and PP groups (P<0.001).

CONCLUSIONS

We conclude that PAS and PP histological specimens exhibit decreased immunostaning of the drug transporter P-gp, and that fetuses born from these pregnancies may be exposed to greater levels of drugs and toxins present at the maternal circulation. Futures studies should attempt to investigate the mechanisms underlying P-gp down-regulation in these obstetric pathologies.

Antenatal screening - The roles of medical and family history, routine tests, and examination findings

Routine antenatal care includes history, examination, and several standard laboratory tests. Other than the original objectives, the generated data is seldom utilised for screening for adverse obstetric and perinatal outcomes. Although new approaches and sophisticated tests improve prediction of complications such as pre-eclampsia, these may not be available globally. Maternal age, race/ethnicity, anthropometry, and method of conception can influence the occurrence of pregnancy complications. The importance of medical and obstetric history is well documented but often ignored. Routine test results including blood picture, hepatitis B and rubella serology, and sexually transmitted diseases, have additional health implications. The awareness of, and the ability to utilise, available antenatal data and tests in obstetric management will enhance individualised obstetric risk assessment thus facilitating the targeting of high-risk gravidae for further management, including the use of specific and technology-driven tests where available, and close monitoring and treatment, in a cost-effective manner.

Neonatal risk factors associated with autism spectrum disorders: an umbrella review

Background

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by severe social communication deficits and stereotypical repetitive behaviors.

PURPOSE

This umbrella review assessed neonatal risk factors associated with ASD using meta-analyses and systematic reviews.

METHODS

We conducted a systematic search of interna- tional databases including PubMed, Scopus, and Web of Science for studies published through April 2022 utilizing pertinent keywords. A random-effects model was used to calculate the odds ratio (OR) and 95% confidence interval (CI). Substantial heterogeneity was considered at values of I2≥50%. A quality assessment of the included studies was performed using the A MeaSurement Tool to Assess Systematic Reviews (AMSTAR2) checklist.

RESULTS

A total of 207,221 children with ASD and 22,993,128 neurotypical children were included. Six meta- analyses were included in this umbrella review. The factors of congenital heart disease (OR, 1.35; 95% CI, 1.17-1.52), macrosomia (OR, 1.11; 95% CI, 1.05-1.18), low birth weight (OR, 1.63; 95% CI, 1.48-1.81), very low birth weight (OR, 2.25; 95% CI, 1.79-2.83), small for gestational age (OR, 1.17; 95% CI, 1.09-1.24), jaundice (OR, 1.74; 95% CI, 1.42- 2.12), male sex (OR, 1.47; 95% CI, 1.39-1.55) and 1-minute Apgar score <7 (OR, 1.40; 95% CI, 1.26-1.55) were graded as suggestive evidence (class III). Only 3 studies reported heterogeneity (I2<50%). Based on the AMSTAR2 analysis, the methodological quality was critically low in 3 meta- analyses, low in 2, and moderate in 1.

CONCLUSION

Based on these results, clinicians should consider the risk factors for ASD and screen children in clinics.

Association between endometriosis and perinatal complications: a case-control study

BACKGROUND

Recently, a history of endometriosis has been reported to be associated with several perinatal complications. However, it is unknown whether pre-pregnancy treatment for endometriosis reduces perinatal complications. In this study, we aimed to clarify the association between endometriosis and perinatal complications and investigate whether there is a significant difference in the incidence of placenta previa depending on the degree of surgical completion of endometriosis before pregnancy.

METHODS

This case-control study included 2781 deliveries at the Hirosaki University Hospital between January 2008 and December 2019. The deliveries were divided into a case group with a history of endometriosis (n = 133) and a control group without endometriosis (n = 2648). Perinatal outcomes and complications were compared between the case and control groups using a t-test and Fisher's exact test. Multiple logistic regression models were used to identify the risk factors for placenta previa. Additionally, we examined whether the degree of surgical completion of endometriosis before pregnancy was associated with the risk of placenta previa.

RESULTS

Patients with a history of endometriosis had a significantly higher risk of placenta previa (crude odds ratio, 2.66; 95% confidence interval, 1.37‒4.83). Multiple logistic regression analysis showed that a history of endometriosis was a significant risk factor for placenta previa (adjusted odds ratio, 2.30; 95% confidence interval, 1.22‒4.32). In addition, among patients with revised American Society for Reproductive Medicine stage III-IV endometriosis, the incidence of placenta previa was significantly lower in patients who underwent complete surgery (3/51 patients, 5.9%) than in those who did not (3/9 patients, 33.3%) (p = 0.038).

CONCLUSIONS

A history of endometriosis is an independent risk factor for placenta previa. Given the limitations of this study, further research is needed to determine the impact of endometriosis surgery on perinatal complications.

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.

Pregnancy outcomes of monochorionic diamniotic and dichorionic diamniotic twin pregnancies conceived by assisted reproductive technology and conceived naturally: a study based on chorionic comparison

OBJECTIVE

To evaluate monochorionic diamniotic (MCDA) and dichorionic diamniotic (DCDA) twin pregnancies conceived by assisted reproductive technology (ART) and conceived naturally.

METHODS

We retrospectively analyzed the data on twin pregnancies conceived by ART from January 2015 to January 2022,and compared pregnancy outcomes of MCDA and DCDA twins conceived by ART with those of MCDA and DCDA twins conceived naturally, pregnancy outcomes between MCDA and DCDA twins conceived by ART, and pregnancy outcomes of DCT and TCT pregnancies reduced to DCDA pregnancies with those of DCDA pregnancies conceived naturally.

RESULT

MCDA pregnancies conceived by ART accounted for 4.21% of the total pregnancies conceived by ART and 43.81% of the total MCDA pregnancies. DCDA pregnancies conceived by ART accounted for 95.79% of the total pregnancies conceived by ART and 93.26% of the total DCDA pregnancies. Women with MCDA pregnancies conceived by ART had a higher premature delivery rate, lower neonatal weights, a higher placenta previa rate, and a lower twin survival rate than those with MCDA pregnancies conceived naturally (all p < 0.05). Women with DCDA pregnancies conceived naturally had lower rates of preterm birth, higher neonatal weights, and higher twin survival rates than women with DCDA pregnancies conceived by ART and those with DCT and TCT pregnancies reduced to DCDA pregnancies (all p < 0.05).

CONCLUSION

Our study confirms that the pregnancy outcomes of MCDA pregnancies conceived by ART are worse than those of MCDA pregnancies conceived naturally. Similarly, the pregnancy outcomes of naturally-conceived DCDA pregnancies are better than those of DCDA pregnancies conceived by ART and DCT and TCT pregnancies reduced to DCDA pregnancies.

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.

The association between of placenta previa and congenital abnormalities: a systematic review and network meta-analysis

BACKGROUND

Congenital abnormalities, as one of the fetal complications of placenta previa, may cause health problems or disability of the child throughout life. This study aimed to determine the relationship between placenta previa and congenital abnormalities.

METHODS

Potential articles were retrieved from three electronic databases (PubMed/Medline, Scopus, and Web of Sciences) up to 21 May 2023 without limit of time and language. A random effect model was applied for meta-analysis. The heterogeneity was calculated based on I2 statistic and Cochrane Q-test. All analyses were conducted at the significance level of 0.05 using STATA software, version 14. The quality assessment of the included studies was performed using the improved Newcastle-Ottawa Scale.

RESULTS

In the initial search, 829 articles were retrieved. Finally, according to the inclusion criteria, eight studies were analyzed in the meta-analysis. A significant association was reported between placenta previa and risk of congenital abnormalities based on crude form (OR = 1.81, 95% CI = 1.34 to 2.28) and adjusted studies (OR = 6.38, 95% CI = 1.47 to 11.30). The high heterogeneity was observed among the studies reported based on adjusted and crude form, respectively (I2 = 97.9%, P = 0.000) (I2 = 80.6%, P = 0.000). Therefore, publication bias was not observed among studies. Seven studies of the included studies were of high quality.

CONCLUSION

Our study provides evidence that there is a positive and significant association between placenta previa and congenital malformations, including all structural anomalies, chromosomal defects, and congenital hypothyroidisms. Therefore, monitoring congenital abnormalities in the fetus of a mother with placenta previa is necessary.

CXCL12/CXCR4/CXCR7 axis in placenta tissues of patients with placenta previa

CXCR4 and CXCR7 have been revealed to be receptors of CXCL12. This research was designed to probe the expression of chemokine CXCL12 and its receptors CXCR4 and CXCR7 in placental tissues of patients with placenta previa and the effect of CXCL12/CXCR4/CXCR7 axis on the biological functions of human trophoblast cells. CXCL12, CXCR4, and CXCR7 expression in placental tissue from patients with placenta previa and healthy puerperae was detected. CXCL12, CXCR4, and CXCR7 expression in human trophoblast cell lines (HTR8/SVneo cells) was assessed after suppression or overexpression of CXCL12, CXCR4, and CXCR7. The cell proliferative, invasive, and migratory capacities were also evaluated in HTR8/SVneo cells after suppression or overexpression of CXCL12, CXCR4, and CXCR7. CXCL12, CXCR4, and CXCR7 expression was elevated in placental tissues from patients with placenta previa. Downregulation of CXCL12, CXCR4, and CXCR7 could lead to decreased mRNA levels of CXCL12, CXCR4, and CXCR7 in HTR-8/SVneo cells, which was accompanied by diminished cell proliferative, migratory, and invasive capabilities. Overexpression of CXCL12, CXCR4, and CXCR7 genes presented an opposite tendency. CXCL12, CXCR4, and CXCR7 are highly expressed in placental tissues of patients with placenta previa and induce the biological activities of HTR8/SVneo cells.

Impact of planned versus emergency cesarean delivery on neonatal outcomes in pregnancies complicated by abnormal placentation: A systematic review and meta-analysis

BACKGROUND

Although planned cesarean delivery (PCD) is the mainstay of management for abnormal placentation, some patients still require emergency cesarean delivery (ECD). We aimed to systematically analyze the impact of various modes of delivery on neonatal outcomes.

METHODS

This study was complied with the PRISMA guidelines and was registered in the PROSPERO (code: CRD42022379487). A systematic search was conducted on Ovid MEDLINE and Embase, Web of Science, PubMed, and the Cochrane databases. Data extracted included gestational age at delivery, birth weight, the Apgar scores at 1 and 5 minutes, numbers of newborns with low Apgar score (<7) at 5 minutes, the rates of neonatal intensive care unit admission, and the rates of neonatal mortality.

RESULTS

Fifteen cohort studies met the inclusion criteria, comprising a total of 2565 women (2567 neonates) who underwent PCD (n = 1483) or ECD (n = 1082) for prenatally diagnosed placenta accreta spectrum (PAS) and/or placenta previa (PP). Compared with the ECD group, neonates in the PCD group had significantly higher gestational ages (standardized mean difference [SMD]: 2.20; 95% confidence interval [CI]: 1.25-3.15; P < .001), birth weights (SMD: 1.64; 95% CI: 1.00-2.27; P < .001), and Apgar scores at 1 minute (SMD: 0.51; 95% CI: 0.29-0.73; P < .001) and 5 minutes (SMD: 0.47; 95% CI: 0.25-0.70; P < .001). Additionally, the PCD group had significantly lower rates of neonatal intensive care unit admission (odds ratio [OR]: 0.21; 95% CI: 0.14-0.29; P < .001), low Apgar score at 5 minutes (OR: 0.27; 95% CI: 0.11-0.69; P = .01), and neonatal mortality (OR: 0.13; 95% CI: 0.05-0.33; P < .001).

CONCLUSION

When pregnancies are complicated by abnormal placentation, PCD is linked to noticeably better neonatal outcomes than emergent delivery.

Placenta accreta spectrum in major placenta previa diagnosed only by MRI: incidence, risk factors, and maternal morbidity

BACKGROUND

Antenatal assessment of maternal risk factors and imaging evaluation can help in diagnosis and treatment of placenta accreta spectrum (PAS) in major placenta previa (PP). Recent evidence suggests that magnetic resonance imaging (MRI) could complement ultrasonography (US) in the PAS diagnosis.

OBJECTIVES

Evaluate the incidence, risk factors, and maternal morbidity related to the MRI diagnosis of PAS in major PP.

DESIGN

A 10-year retrospective cohort study.

SETTING

Tertiary care hospital.

PATIENTS AND METHODS

We report on patients with major PP who had cesarean delivery in Abha Maternity and Children's Hospital (AMCH) over a 10-year period (2012-2021). They were evaluated with ultrasonography (US) and color Doppler for evidence of PAS. Antenatal MRI was ordered either to confirm the diagnosis (if equivocal US) or to assess the depth of invasion/extra-uterine extension (if definitive US).

MAIN OUTCOME MEASURES

Risk factors for PAS in major PP and maternal complications.

SAMPLE SIZE

299 patients RESULTS: Among 299 patients, MRI confirmed the PAS diagnosis in 91/299 (30.5%) patients. The independent risk factors for MRI diagnosis of PAS in major PP included only repeated cesarean sections and advanced maternal age. The commonest maternal morbidity in major PP with PAS was significantly excessive intraoperative bleeding.

CONCLUSION

MRI may be a valuable adjunct in the evaluation of PAS in major PP; as a complement, but not substitute US. MRI may be suitable in major PP/PAS patients who are older and have repeated cesarean deliveries with equivocal results or deep/extra-uterine extension on US.

LIMITATION

Single center, small sample size, lack of complete histopathological diagnosis.

CONFLICT OF INTEREST

None.

Effect of gestational diabetes mellitus on pregnancy outcomes among younger and older women and its additive interaction with advanced maternal age

Background

The prevalence of gestational diabetes mellitus (GDM) and advanced maternal age (AMA, ≥ 35 years) has shown an increasing trend worldwide. This study aimed to evaluate the risk of pregnancy outcomes among younger (20-34 years) and older (≥ 35 years) women with GDM and further analyze the epidemiologic interaction of GDM and AMA on these outcomes.

Methods

This historical cohort study included 105 683 singleton pregnant women aged 20 years or older between January 2012 and December 2015 in China. Stratified by maternal age, the associations between GDM and pregnancy outcomes were analyzed by performing logistic regression. Epidemiologic interactions were assessed by using relative excess risk due to interaction (RERI), attributable proportion due to interaction (AP), and synergy index (SI) with their 95% confidence intervals (95%CIs).

Results

Among younger women, individuals with GDM had a higher risk of all maternal outcomes, preterm birth (relative risk [RR] 1.67, 95%CI 1.50-1.85), low birthweight (RR 1.24, 95%CI 1.09-1.41), large for gestational age (RR 1.51, 95%CI 1.40-1.63), macrosomia (RR 1.54, 95%CI 1.31-1.79), and fetal distress (RR 1.56, 95%CI 1.37-1.77) than those without GDM. Among older women, GDM increased the risk of gestational hypertension (RR 2.17, 95%CI 1.65-2.83), preeclampsia (RR 2.30, 95%CI 1.81-2.93), polyhydramnios (RR 3.46, 95%CI 2.01-5.96), cesarean delivery (RR 1.18, 95%CI 1.10-1.25), preterm birth (RR 1.35, 95%CI 1.14-1.60), large for gestational age (RR 1.40, 95%CI 1.23-1.60), macrosomia (RR 1.65, 95%CI 1.28-2.14) and fetal distress (RR 1.46, 95%CI 1.12-1.90). Additive interactions of GDM and AMA on polyhydramnios and preeclampsia were found, with RERI of 3.11 (95%CI 0.05-6.16) and 1.43 (95%CI 0.09-2.77), AP of 0.51 (95%CI 0.22-0.80) and 0.27 (95%CI 0.07-0.46), and SI of 2.59 (95%CI 1.17-5.77) and 1.49 (95%CI 1.07-2.07), respectively.

Conclusion

GDM is an independent risk factor for multiple adverse pregnancy outcomes, and may exert additive interactions with AMA on the risk of polyhydramnios and preeclampsia.

Factors associated with poorer childbirth outcomes in pregnant women diagnosed with placenta previa

OBJECTIVE

Placenta previa is a health issue during pregnancy when the placenta wholly or partially covers the opening of the uterus. It can result in bleeding during pregnancy or after delivery, and preterm delivery. This study aimed to investigate the risk factors correlated with poorer childbirth outcomes of placenta previa.

MATERIALS AND METHODS

Between May 2019 and January 2021, pregnant women diagnosed with placenta previa in our hospital were enrolled. Outcomes were postpartum hemorrhage after childbirth, and lower Apgar score and preterm delivery of the neonate. Laboratory blood examination data preoperatively were collected from medical records.

RESULTS

A total of 131 subjects were included, with a median age 31 years. Multivariate analysis showed that fibrinogen reduced risk for postpartum hemorrhage (adjusted odds ratio (aOR): 0.45, 95% confidence interval (CI): 0.26-0.79, p = 0.005). Homocysteine (aOR: 0.73, 95% CI: 0.54-0.99, p = 0.04) reduced the risk while D-dimer (aOR: 1.19, 95% CI: 1.02-1.37, p = 0.02) increased the risk for low Apgar score. Age (aOR: 0.86, 95% CI: 0.77-0.96, p = 0.005) decreased the risk but history of full-term pregnancy more than twice (aOR: 8.58, 95% CI: 2.32-31.71, p = 0.001) increased the risk for preterm delivery.

CONCLUSION

The findings suggest that poorer childbirth outcomes in pregnant women with placenta previa are associated with young age, history of full-term pregnancy, and preoperative concentrations of low fibrinogen, low homocysteine and high D-dimer. This provides obstetricians adjunctive information for early screening of high-risk population and relevant treatment arrangement in advance.

Desenlaces maternos según el tipo de placenta previa en un hospital de alta complejidad en Cali, Colombia. Estudio de cohorte retrospectivo

Objetivos: describir la frecuencia de complicaciones maternas en mujeres gestantes con placenta previa (PP) mayor o menor y evaluar una posible de asociación entre tipo de PP y la presencia de hemorragia materna severa y otros resultados maternos asociados. Materiales y métodos: cohorte retrospectiva, descriptiva. Se incluyeron gestantes con 20 semanas o más de embarazo, con diagnóstico confirmado de placenta previa, quienes fueron atendidas en un hospital de alto nivel de complejidad localizado en Cali (Colombia), entre enero de 2011 y diciembre de 2020. Se excluyeron las gestantes con diagnóstico de placenta previa y acretismo placentario concomitante. Las variables recolectadas fueron: edad materna, índice de masa corporal, tabaquismo, obesidad, paridad, presencia de sangrado, hemorragia posparto, manejo de la hemorragia posparto, transfusión y admisión a UCI de la gestante. Se realizó análisis descriptivo. El protocolo fue aprobado por el comité de ética de la Fundación Valle de Lili. Resultados: 146 pacientes cumplieron con los criterios de inclusión. La población estuvo constituida por mujeres con una mediana de edad de 32 años, sin antecedente quirúrgico, con diagnóstico prenatal de placenta previa a la semana 22. En el 70,5 % de los casos se trató de pacientes con placenta previa mayor. Las complicaciones más frecuentes fueron hemorragia posparto (37,9 % vs. 16,3 % para pacientes con placenta previa mayor y menor, respectivamente), requerimiento de transfusión (23,3 y 9,3 %, respectivamente) y el ingreso materno a la UCI (40,8 % vs. 18,6 %, respectivamente). No se registraron muertes maternas. Conclusiones: las mujeres con placenta previa experimentan una frecuencia elevada de complicaciones; probablemente, dicha frecuencia es más alta cuando se documenta placenta previa mayor. Se requieren más estudios que comparen la frecuencia de complicaciones maternas según el tipo de placenta previa.

The environmental risk factors associated with ectopic pregnancy: An umbrella review

INTRODUCTION

Ectopic pregnancy(EP) is the implantation of a fertilized ovum outside of the uterine cavity. The incidence of EP has steadily increased around the world. The present umbrella review evaluated risk factors prior to conception associated with EP based on meta-analyses and systematic reviews.

METHODS

We searched PubMed, Scopus, and Web of Science until June 25, 2021. All meta-analyses that had focused on assessing the risk factors associated with EP were included. We calculated summary effect estimates, 95% CI, heterogeneity I², 95% prediction interval, small-study effects, excess significance biases, and sensitive analysis. The quality of the meta-analyses was evaluated with A Measurement Tool to Assess Systematic Reviews 2 (AMSTAR 2).

RESULTS

Two risk factors including chlamydia trachomatis (OR: 3.03) and smoking (OR: 1·77) were graded as suggestive evidence (class III). IUD with pregnant control (OR: 10.63) and endometriosis for case-control studies (OR: 2·66) and tubal ligation with pregnant control (OR: 9.3) were graded as risk factors with weak evidence (class IV). Tubal ligation with non-pregnant control was a protective factor (class IV). IUD with non-pregnant control and endometriosis for cohort studies were not as risk factors for EP.

CONCLUSION

Two risk factors including chlamydia trachomatis and smoking were graded as suggestive evidence. IUD with pregnant control and endometriosis for case-control studies and tubal ligation with pregnant control were graded as risk factors with weak evidence. Strong evidence for risk factors of EP was not achieved, indicating the degree of uncertainty and bias, which bring an emergency to conduct further no-bias studies.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO (CRD42021281632).

Potential resolution of placenta previa from the 28th-to the 36th-week of pregnancy: A retrospective longitudinal cohort study

INTRODUCTION

Placenta previa greatly contributes to severe antenatal and post-partum hemorrhage. Previous studies have mainly focused on the risk factors of placenta previa, with very few studies reporting which factors may affect the potential resolution of 28th-week previa. This study aimed to investigate the impact of maternal characteristics on potential resolution of placenta previa from the 28th-to the 36th-week of pregnancy.

METHODS

A retrospective longitudinal sub-cohort investigation was carried out among 368 pregnant women with 28th-week previa from the Longitudinal Placenta Previa Study (LoPPS). Logistic regression analysis was used to discover the connections between maternal covariates and the placental potential resolution. Multivariable linear regression analysis was used to detect the associations between perioperative characteristics and volume of intraoperative bleeding.

RESULTS

Among pregnant women whose placenta completely or partially covered the internal os at the 28th-week of pregnancy, 37.5% were without placenta previa at the 36th-week and 25.8% converted into marginal placenta previa. There were significant correlation between placenta previa type and GHD (Beta: 2.808, 95% CI: 1.642, 7.138; p = 0.041), type of 28th-week previa (Beta: 6.767, 95% CI: 1.592, 18.767; p < 0.001), and number of prior cesarean sections (Beta: 3.326, 95% CI: 1.580, 9.081; p < 0.001).

DISCUSSION

62.5% of the pregnant women with 28th-week placenta previa were still with previa at the 36 weeks of gestation (25.8% with marginal and 36.7% with partial/complete placenta previa). This proportion is even higher for 28th-week complete placenta previa.

TRIAL REGISTRATION

Chinese Clinical Trial Registry ChiCTR2100054068, December 8, 2021.

The environmental risk factors prior to conception associated with placental abruption: an umbrella review

BACKGROUND

The present umbrella review evaluated risk factors prior to conception associated with placental abruption based on meta-analyses and systematic reviews.

METHODS

We searched PubMed, Scopus, and Web of Science until June 25, 2021. All meta-analyses that had focused on assessing the risk factors associated with placental abruption were included. We calculated summary effect estimates, 95% CI, heterogeneity I2, 95% prediction interval, small-study effects, excess significance biases, and sensitive analysis. The quality of the meta-analyses was evaluated with A Measurement Tool to Assess Systematic Reviews 2 (AMSTAR 2).

RESULTS

There was no risk factor in the present umbrella review with the high level of evidence (class I or II). Eight risk factors including maternal asthma (RR 1.29 95% CI 1.14, 1.47), prior cesarean section (RR 1.38, 95% CI 1.35-1.42), cocaine using (RR 4.55, 95% CI 1.78-6.50), endometriosis (OR 1.40, 95% CI 1.12-1.76), chronic hypertension (OR 3.13, 95% CI 2.04-4.80), advanced maternal age (OR 1.44, 95% CI 1.35-1.54), maternal smoking (OR 1.80, 95% CI 1.75-1.85) (RR 1.65, 95% CI 1.51-1.80), and use of assisted reproductive techniques (ART) (OR 1.87, 95% CI 1.70-2.06) were graded as suggestive evidence (class III). The other four risk factors including pre-pregnancy underweight (OR 1.38, 95% CI 1.12-1.70), preeclampsia (OR 1.73, 95% CI 1.47-2.04), uterine leiomyoma (OR 2.63, 95% CI 1.38-3.88), and marijuana use (OR 1.78, 95% CI 1.32-2.40) were graded as risk factors with weak evidence (class IV).

CONCLUSION

Maternal asthma, prior cesarean section, cocaine use, endometriosis, chronic hypertension, advanced maternal age, maternal smoking, and use of ART, pre-pregnancy underweight, preeclampsia, uterine leiomyoma, and marijuana use were risk factors associated with placental abruption. Although factors associated with placental abruption have been investigated, the current meta-analytic associations cannot disentangle the complex etiology of placental abruption mainly due to their low quality of evidence.