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

A History of Cesarean Birth as a Risk Factor for Postpartum Hemorrhage Even After Successful Planned Vaginal Birth

BACKGROUND

It is unclear if a history of cesarean birth (CB) is a risk factor for postpartum hemorrhage (PPH) even after a successful planned vaginal birth.

METHODS

A historical retrospective cohort study from all deliveries (42,456) between 2004 and 2019. Inclusion criteria were as follows: (i) women with only one previous CB; (ii) liveborn cephalic singleton pregnancy and term spontaneous labor; (iii) successful planned vaginal birth; (iv) no operative vaginal delivery; and (v) no history of PPH. Women who experienced intrapartum uterine rupture leading to CB were excluded. Those who experienced uterine rupture diagnosed after vaginal birth were not excluded. The labor after cesarean (LAC) group (109 women with previous CB and current vaginal birth) were compared with 2 control groups to consider the parity: control group 1 (1633 nulliparous women) and control group 2 (4197 parous women). The main outcome was the rate of PPH (> 500 mL). Multivariate analysis was performed to investigate whether previous CB was an independent risk factor for PPH. Bivariate analysis and causal framework was used to determine the relation between variables of clinical interest.

RESULTS

The PPH rates in the LAC group, control group 1, and control group 2 were 12.8%, 5.3%, and 6.4%, respectively. Irrespective of the group control (1 or 2), a history of CB was associated with an increased risk of PPH: adjusted odds ratio (aOR) 2.38 [95% confidence interval (CI) 1.28-4.44] (adjusted with maternal age, overweight, hyperthermia, and use of oxytocin) and aOR 2.16 [95% CI 1.20-3.87] (adjusted with maternal age and overweight) for Groups 1 (parous) and 2 (nulliparous), respectively.

CONCLUSION

A history of cesarean birth could be a risk factor for PPH even after successful planned vaginal delivery.

Placental Location Site and Associated Intrapartum, Postpartum, and Neonatal Complications: A Comprehensive Review and Meta-Analysis

Background/Objectives: Adverse intrapartum, postpartum, and neonatal complications have been linked to placenta implantations sites. However, different reviews have led to contrasting conclusions about placental locations and pregnancy outcomes. We aim to determine if there is a relationship between the placental implantation site and intrapartum, postpartum, and neonatal outcomes. Methods: The Meta-analysis of Observational Studies in Epidemiology (MOOSE) guidelines were followed during this review. The literature search used PubMed, CINAHL, and Embase. Years searched was not a study limitation. Only articles in English were included. Two authors reviewed the abstracts. Results: Of 40 articles identified as specific to intrapartum, postpartum, and/or neonatal complications (with some articles overlapping categories), 19 included intrapartum complications, 19 included postpartum complications, and 22 included neonatal complications. Pregnancies with a midline placenta (compared to a lateral placenta) had a greater likelihood of macrosomia/LGA infant (odds ratio (OR), 1.52 (95% CI: 1.22-1.90)) and lesser likelihood to have non-cephalic presentation (OR, 0.17 (95% CI: 0.06-0.51)), FGR/SGA infant (OR, 0.68 (CI: 0.55-0.85)), and retained placenta (OR, 0.33 (95% CI: 0.22-0.50)). Pregnancies with a low-lying placenta (compared to within uterine corpus) were more likely to have non-elective cesarean section (OR, 1.94 (95% CI: 1.06-3.55)) and postpartum hemorrhage (OR 1.49 (95% CI: 1.12-1.97)). Conclusions: Significant associations between placental location site and intrapartum complications (non-cephalic presentation, non-elective cesarean section), postpartum complications (postpartum hemorrhage, retained placenta), and neonatal complications (FGR/SGA, Macrosomia/LGA) were identified. There were no significant associations identified between the placental location site and several neonatal complications, including Apgar < 7 at 5 min, NICU admission, IUFD, and neonatal death.

Is there an association between lateral uterine localization of the placenta and pregnancy outcomes?

PURPOSE

To evaluate the association between lateral placentation and adverse perinatal outcomes, including rates of small for gestational age (SGA) neonates, hypertensive (HTN) disorders, and preterm delivery, as well as postpartum hemorrhage and retained placenta.

METHODS

This retrospective cohort study included all women with singleton pregnancies who underwent a trial of labor after reaching 24 weeks of gestation, at a single tertiary medical center, over a period of 6 years. The study group included women with lateral placentation. Controls were women with anterior, posterior, or fundal placentation. Power analysis indicated that 882 women in each group would be sufficient to detect an increased rate of the primary outcomes: preterm delivery, hypertensive disorders or SGA in the lateral placenta group. Secondary outcomes were Apgar score, cord pH and retained placenta.

RESULTS

Overall, 1,817 (7.6%) women had lateral placenta and 21,991 (92.4%) anterior, posterior, or fundal placentation. No significant differences were observed between groups in the rates of hypertensive disorders, SGA or preterm birth. Lateral placentation was associated with a longer third stage of labor (11.1 ± 8.6 min vs. 10.4 ± 7.2 min, p = 0.001) and higher rate of retained placenta (5.7% vs. 4.2%, p = 0.002). Multivariate regression found that lateral placentation was independently associated with longer third stage of labor.

CONCLUSION

Lateral placentation was not associated with increased rates of hypertensive disorders, preterm birth or SGA infants. It was linked to a longer third stage of labor but without a significant impact on maternal or perinatal complications.

Association between placental location and cord insertion site with pre-eclampsia: a retrospective cohort study

OBJECTIVE

The relationship between placental location in pregnancies without previa and adverse pregnancy outcomes has not been well studied. Additionally, the impact of abnormal cord insertion sites remains controversial. Therefore, the objective of this study was to explore the adverse outcomes associated with placental location and abnormal cord insertion in nulliparous women and to assess their impact on pregnancy outcomes.

METHODS

This retrospective cohort study was conducted at a single tertiary hospital between January 2019 and June 2022. The study included nulliparous women with singleton pregnancies who delivered live infants and had available data on placental location and umbilical cord insertion site from a second- or third-trimester ultrasound. Placental location was categorized as anterior or posterior using transabdominal ultrasonography. The association between placental location/cord insertion site and pre-eclampsia was evaluated using multivariate logistic regression analysis. We compared the area under the curve to evaluate the impact of placental location and cord insertion site on pre-eclampsia.

RESULTS

A total of 2219 pregnancies were included in the study. Pre-eclampsia occurred significantly more frequently in the anterior group than in the posterior group (8.21% vs. 3.04%, p < .001). In multivariate analysis investigating the association between placental location and pre-eclampsia, anterior placenta and marginal cord insertion showed increased odds ratios for pre-eclampsia of 3.05 (95% confidence interval [CI] 1.68-6.58) and 3.64 (95% CI 1.90-6.97), respectively. Receiver operating characteristic (ROC) curves were constructed to predict pre-eclampsia using independent factors from multivariate analyses. Model I, including maternal age, pre-pregnancy body mass index, in vitro fertilization, chronic hypertension, overt diabetes, kidney disease, and hematologic diseases, achieved an area under the ROC curve of 0.70 (95% CI 0.65-0.75). Adding cord insertion site and placental location to the model (Model II) improved its predictive performance, resulting in an area under the ROC curve of 0.749 (95% CI 0.70-0.79, p = .02).

CONCLUSIONS

Anterior placenta and marginal cord insertion were associated with an increased risk of pre-eclampsia. Further studies on prospective cohorts are necessary to validate these findings.

Prevalence of preterm birth in Scandinavian countries: a systematic review and meta-analysis

OBJECTIVES

As welfare societies, Scandinavian countries share characteristics of equality related to healthcare access, gender, and social services. However, cultural and lifestyle variations create country-specific health differences. This meta-analysis assessed the prevalence of preterm birth (PTB) and its categories in Scandinavian countries.

METHODS

A systematic search in key databases of literature published between 1990 and 2021 identified studies of the prevalence of PTB and its categories. Following the use of the Freeman-Tukey double arcsine transformation, a meta-analysis of weighted data was performed using the random-effects model and meta-prop method.

RESULTS

We identified 109 observational studies that involved 86,420,188 live births. The overall pooled prevalence (PP) of PTB was 5.3% (PP = 5.3%, 95% confidence interval [CI] 5.1%, 5.5%). The highest prevalence was in Norway (PP = 6.2%, 95% CI 5.3%, 7.0%), followed by Sweden (PP = 5.3%, 95% CI 5.1%, 5.4%), Denmark (PP = 5.2%, 95% CI 4.9%, 5.3%), and Iceland (PP = 5.0%, 95% CI 4.4%, 5.7%). Finland had the lowest PTB rate (PP = 4.9%, 95% CI 4.7%, 5.1%).

CONCLUSIONS

The overall PP of PTB was 5.3%, with small variations among countries (4.9%-6.2%). The highest and lowest PPs of PTB were in Norway and Finland, respectively.

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.

Placental location and obstetrical-neonatal outcomes: A retrospective study

OBJECTIVE

To explore the potential association of lateral placentation with pregnancy outcome.

METHODS

The database of a tertiary medical center was searched for women who gave birth to a singleton neonate from 2012 to 2020 for whom placental location was documented during antepartum sonographic examination. Clinical data were compared between patients with a central (anterior/posterior/fundal) or lateral placenta using standard statistics. The primary outcome measure was neonatal birthweight, and secondary outcome measures were pregnancy complications and mode of delivery.

RESULTS

The cohort included 12 306 women: 11 608 (94%) with a central placenta and 698 (5.6%) with a lateral placenta. The lateral placenta group had higher rates (P < 0.05) of prior and current cesarean delivery, assisted delivery, and preterm birth. On multivariate regression analyses, placental location (adjusted odds ratio [aOR], 1.36; 95% confidence interval [CI], 1.11-1.66) and maternal age (aOR, 1.02; 95% CI, 1.01-1.03) were associated with risk of preterm birth. Lateral placenta (aOR, 1.22; 95% CI, 1.02-1.47), maternal age (aOR, 1.07; 95% CI, 1.06-1.08), parity (aOR, 0.32; 95% CI, 0.28-0.35), and prior cesarean delivery (aOR, 12.00; 95% CI, 10.60-13.60) were associated with risk of current cesarean delivery.

CONCLUSION

The findings suggest that lateral placentation may pose a risk of preterm birth and cesarean delivery compared with central placentation.

Shear wave velocity measurement of the placenta is not limited by placental location

INTRODUCTION

Ultrasound elastography shows diagnostic promise via the non-invasive determination of placental elastic properties. A limitation is a potential for inadequate measurements from posterior placentae. This study aimed to analyse placental position's influence on measures of shear wave elastography (SWV).

METHODS

SWV elastography measurements were obtained via ultrasound at 24, 28 and 36 weeks gestation from 238 pregnancies. . The placental position was labelled as either anterior, posterior or fundal/lateral. Average SWV measurements (m/s) and the corresponding standard deviations (SD) were used for data analysis.

RESULTS

There was a statistically significant difference between SWV recorded from anterior (1.33 ± 0.19)m/s and posterior (1.39 ± 0.18)m/s placentae (p < 0.001). However, the average sampling depth between these groups was significantly different (3.98 cm vs. 5.38 cm, p < 0.001). There was no statistically significant difference between SWV when measurements were compared at similar depths, regardless of placental location. The addition of placental position to a previously developed mixed-effects model confirmed placental position did not result in improved SWV measurements. In this model, sampling depth remained the best predictor for SWV.

CONCLUSIONS

This study showed that placental position does not influence the accuracy or reliability of SWV.

The Stockholm-Gotland perinatal cohort-A population-based cohort including longitudinal data throughout pregnancy and the postpartum period

BACKGROUND

Register-based reproductive and perinatal databases rarely contain detailed information from medical records or repeated measurements throughout pregnancy and delivery. This lack of enriched pregnancy and birth data led to the initiation of the Swedish Stockholm-Gotland Perinatal Cohort (SGPC).

OBJECTIVES

To describe the strengths of the SGPC, as well as the unique research questions that can be addressed using this cohort.

POPULATION

The SGPC is a prospectively collected, population-based cohort that includes all births (from 22 completed gestational weeks onwards) between 1 January 2008 and 15 June 2020 in the Stockholm and Gotland regions of Sweden (N 335,153 singleton and N 11,025 multiple pregnancies).

DESIGN

Descriptive study.

METHODS

The SGPC is based on the electronic medical records of women and their infants. The medical record system is used for all antenatal clinic visits and admissions, delivery and neonatal admissions, as well as postpartum clinical visits. SGPC has been further enriched with data linkages to 10 Swedish National Health Care and Quality Registers.

PRELIMINARY RESULTS

In contrast to other reproductive and perinatal databases available in Sweden, including the Medical Birth Register and the Pregnancy Register, SGPC contains highly detailed medical record data, including time-varying serial measurements for physiological parameters throughout pregnancy, delivery, and postpartum, for both mother and infant. These strengths have enabled studies that were previously inconceivable; the effects of serial measurements of pregnancy weight gain, changes in haemoglobin counts and blood pressure during pregnancy, fetal weight estimations by ultrasound, duration of stages and phases of labour, cervical dilatation and oxytocin use during delivery, and constructing reference curves for umbilical cord pH.

CONCLUSIONS

The SGPC-with its rich content, repeated measurements and linkages to numerous health care and quality registers-is a unique cohort that enables high-quality perinatal studies that would otherwise not be possible.

The impact of lateral placenta on preeclampsia and small for gestational age neonates: a systematic review and meta-analysis

OBJECTIVES

We conducted a systematic review and meta-analysis to quantitatively summarize the present data on the association of prenatally identified lateral placenta in singleton pregnancies with small for gestational age (SGA) neonates, preeclampsia and other perinatal outcomes.

METHODS

From inception to November 2021, we searched PubMed/Medline, Scopus and The Cochrane Library for papers comparing the risk of SGA and preeclampsia, as well as other perinatal outcomes in singleton pregnancies with a prenatally identified lateral placenta to those with non-lateral placentas. The revised Newcastle-Ottawa Scale was used to evaluate the quality of eligible papers. The I² test was employed to evaluate the heterogeneity of outcomes among the studies. To investigate the possibility of publication bias, funnel plots were constructed. Prospero RN: CRD42021251590.

RESULTS

The search yielded 5,420 articles, of which 16 were chosen, comprising of 15 cohort studies and one case control study with a total of 4,947 cases of lateral and 96,035 of non-lateral placenta (controls) reported. SGA neonates were more likely to be delivered in cases with a lateral placenta (OR: 1.74; 95% CI: 1.54-1.96; p<0.00001; I²=47%). Likewise, placental laterality was linked to a higher risk of fetal growth restriction (OR: 2.18; 95% CI: 1.54-3.06; p<0.00001; I2=0%), hypertensive disorders of pregnancy (OR: 2.39; 95% CI: 1.65-3.51; p=0.0001; I²=80%), preeclampsia (OR: 2.92; 95% CI: 1.92-4.44; p<0.0001; I²=82%) and preterm delivery (OR: 1.65; 95% CI: 1.46-1.87; p<0.00001; I²=0%).

CONCLUSIONS

The prenatal diagnosis of a lateral placenta appears to be associated with a higher incidence of preeclampsia, fetal growth restriction, preterm delivery and SGA. This may prove useful in screening for these conditions at the second trimester anomaly scan.

Association between placental location and neonatal outcomes in manual fundal pressure-assisted vaginal deliveries: A retrospective single-center study in Japan

AIM

Manual fundal pressure (MFP) is still used to assist vaginal deliveries during the second stage of labor in predominantly lower-middle income countries; however, there is insufficient evidence on the risk factors in MFP-assisted vaginal deliveries for adverse neonatal outcomes. The aim of the present study was to investigate the association between placental location and neonatal outcomes in MFP-assisted vaginal deliveries.

METHODS

The present study was a single-center retrospective cohort study in patients with all MFP-assisted vaginal singleton deliveries from January 2016 to December 2020. Placental location was divided into two categories: posterior-lateral and anterior-fundal. The primary outcome was a neonatal adverse composite including umbilical artery blood pH <7.2, Apgar score <7 at 5 min, neonatal intensive care unit admission and neonatal resuscitation. We used multivariable logistic regression models to investigate the association between placental location and neonatal outcomes.

RESULTS

We extracted 522 MFP-assisted deliveries among 5053 vaginal deliveries. The proportion of posterior-lateral and anterior-fundal placentation was 239 (45.8%) and 283 (54.2%), respectively. The crude prevalence of neonatal composite outcome in the anterior-fundal group was significantly higher than that in the posterior-lateral group (39.6% vs. 28.9%; p = 0.013). Multivariable logistic regression analysis found that the prevalence of neonatal adverse outcome in the anterior-fundal group was significantly higher compared with the posterior-lateral group (adjusted odds ratio, 1.52; 95% confidence interval, 1.04-2.23).

CONCLUSION

Anterior-fundal placentation was significantly associated with an increased risk of neonatal adverse outcomes compared to posterior-lateral placentation in MFP-assisted vaginal deliveries.

Association of placental chorangiosis with pregnancy complication and prenatal outcome: a case-control study

Background

Chorangiosis is a vascular change involving the terminal chorionic villi in the placenta. It results from longstanding, low-grade hypoxia in the placental tissue, and is associated with such conditions as intrauterine growth restriction (IUGR), diabetes, and gestational hypertension in pregnancy. Chorangiosis rarely occurs in normal pregnancies. However, its prevalence is 5–7% of all placentas from infants admitted to newborn intensive care units. The present study was aimed at determining the association of chorangiosis with pregnancy complications and perinatal outcomes.

Methods

In this case-control study, 308 chorangiosis cases were compared with 308 controls (with other diagnoses in pathology) in terms of maternal, placental, prenatal, and neonatal characteristics derived from the medical records of participants retrospectively. R and SPSS version 22 software tools were used, and the statistical significance level was considered 0.05 for all the tests.

Results

Preeclampsia, diabetes mellitus, maternal hemoglobin, maternal hematocrit, C/S, oligohydramnios, fetal anomaly, dead neonates, NICU admissions were significantly higher in the chorangiosis group OR = 1.6, 3.98, 1.68, 1.92, 2.1, 4.47, 4.22, 2.9, 2.46, respectively (p-value< 0.05 for all). Amniotic fluid index, birth weight, cord PH amount, 1st, and 5th Apgar score was lower in the chorangiosis group OR = 0.31, 1, 0.097, 0.83, 0.85, respectively (p-value< 0.05 for all). Moreover, fundal placenta, retro placental hemorrhage, perivillous fibrin deposition, calcification, and acute chorioamnionitis were higher in the chorangiosis group OR = 2.1, 11.8, 19.96, 4.05, and 6.38 respectively, (p-value< 0.05). There was a high agreement between the two pathologists, and the power of the study was estimated at 99%.

Conclusion

Although chorangiosis is an uncommon condition, it is associated with a higher incidence of perinatal and neonatal morbidity and mortality. Therefore, it should be considered an important clinical sign of adverse pregnancy outcomes and should be reported in the pathology evaluation.

Cigarette smoke induced neural tube defects by down-regulating noggin expression

BACKGROUND

Maternal smoking or passive smoking during gestation increases the risk of congenital birth defects, including neural tube defects (NTDs). Cigarette smoke is a recognized teratogen that causes NTDs, although the mechanisms are not well understood.

METHODS

An established model of passive smoking in pregnant golden hamsters was used to observe the effect of cigarette smoke on neural tube development using scanning electron microscopy. Level of noggin expression in placenta and neural tube was evaluated by immunohistochemistry.

RESULTS

Our results indicated that cigarette smoke can cause the neural tube closure of the golden hamster embryo to be delayed or not closed. In normal placental tissues noggin protein and RNA levels were highly expressed, and the expression level in the term placenta was lower than in that of the first trimester or second trimester through analyzing the Human Protein Atlas and the Gene Expression Omnibus (GEO) databases. Cigarette smoke can down-regulate noggin expression in the placenta and promote cell apoptosis. We observed that noggin expression was reduced and BMP2 expression was increased by cigarette smoke.

CONCLUSIONS

Cigarette smoke may cause cell apoptosis and accelerate placenta maturation. Meanwhile, cigarette smoke may inhibit the development of the embryo, and lead to the formation of NTDs via downregulating the expression of noggin and dis-inhibition of BMP2.

Risk factors for third stage placental complications among primigravid women

INTRODUCTION

Third stage placental complications (TSPC) including partially or complete retained placenta, are a common obstetric complication. Previous studies have underlined risk factors for TSPC in heterogenous populations of women, whereas data regarding primigravid term women are scarce. We aimed to identify the factors associated with TSPC in this subset of parturients.

METHODS

A retrospective cohort study including all primigravid women who delivered vaginally a term, live-singleton neonate between 2011 and 2019. Women who underwent revision of the uterine cavity due to TSPC were compared with those who did not. Univariate and multivariate regression analyses were performed in order to identify the risk factors for TSPC.

RESULTS

Overall, 16,867 deliveries met the study inclusion criteria. Of those, 1097 (6.5%) deliveries were complicated by TSPC. Women with TSPC were older (p < 0.001) and with a higher proportion of lateral and fundal placental location (p < 0.001). In a multivariate regression analysis, the following factors were positively independently associated with TSPC: maternal age (aOR [95% CI] 1.26 (1.17-1.36), p < 0.001), the use of assisted reproduction technologies (aOR [95% CI] 1.26 (1.06-1.49), p = 0.007), preeclampsia (aOR [95% CI] 3.39 (1.89-6.10), p < 0.001), thrombocytopenia (aOR [95% CI] 1.83 (1.34-2.48), p < 0.001), oxytocin administration (aOR [95% CI] 1.29 (1.12-1.48), p < 0.001) and longer second stage duration (aOR [95% CI] 1.03 (1.003-1.05), p = 0.02). Fetal male gender was negatively associated with TSPC (aOR [95% CI] 0.80 (0.70-0.92), p = 0.002).

DISCUSSION

We have identified multiple independent risk factors for TSPC among primigravid women. This information can aid in patient counseling and delivery management in these subset of parturients.

The effect of placental laterality at 20-24 gestational weeks on uterine artery doppler indices, fetal growth and preeclampsia

BACKGROUND

This study aimed (i) to assess the potential effect of placental location on uterine artery (UtA) pulsatility index (PI) and offspring birthweight (BW), and (ii) to examine the potential association of unilaterally increased UtA PI with preeclampsia (PE) or low BW.

MATERIALS AND METHODS

This was an asynchronous cohort study of singleton pregnancies between 20⁺⁰ and 23⁺⁶ gestational weeks resulting in live birth, for whom the placental site (posterior, anterior, fundal, previa, right lateral, or left lateral) and bilateral UtA PI measurements were recorded. The effect of placental location on mean BW and UtA mean PI z-scores was assessed using t-test or ANOVA and post-hoc tests, as appropriate. The UtA PI measurements were then grouped into three categories (normal mean PI; unilaterally increased PI with normal mean; increased mean PI) and we calculated the odds ratios (ORs) of unilaterally increased or increased mean PI vs. normal mean PI for PE, BW <10th centile and BW <5th centile. The independent association of placental location, UtA PI category (normal mean, unilateral increase with normal mean, increased mean PI) and UtA PI z-score with PE, BW <10th centile and BW <5th centile was then assessed using logistic regression.

RESULTS

The analysis included 5506 pregnancies. A lateral placenta was associated with higher mean PI z-score (p = .0001) and lower BW (p = .003) than non-lateral placenta. Compared with normal mean UtA PI, a unilaterally increased PI with a normal mean was associated with increased risk for PE (OR 4.3, 95%CI 1.9-9.7), BW <10th centile (OR 1.7, 95%CI 1.3-2.4) and BW <5th centile (OR 1.8, 95%CI 1.1-2.9). Similarly, increased mean UtA PI was also associated with increased risk for PE, BW <10th and BW <5th centile (OR 9.1, 95%CI 4.8-17.3; OR 4.4, 95%CI 3.5-5.7; OR 7.0, 95%CI 5.1-9.6, respectively). When assessing the independent association of placental location and UtA PI with PE and low BW, only mean UtA PI remains a significant predictor.

CONCLUSIONS

A lateral placenta is associated with a higher mean UtA PI and lower BW. Unilaterally increased UtA PI still carries a greater risk of PE and low BW than bilaterally normal PI, however this effect appears to be eventually mediated through mean UtA PI z-score, which is relatively increased in these cases.

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.

The effect of placental location identified before delivery on birthweight discordance among diamniotic-dichorionic twin pregnancies: a three-year retrospective cohort study

This retrospective cohort study aimed to investigate the effect of placental location on birthweight discordance among diamniotic-dichorionic twin pregnancies. Medical records and sonographic reports of 978 diamniotic-dichorionic twin pregnancies delivered at Foshan Maternal and Fetal Health Hospital were reviewed. Pregnancies with congenital malformation, intrauterine death or placenta previa were excluded. The placental location for each twin was determined by last sonographic examination before delivery, and the pregnancies were grouped by different versus same placental location in each pregnancy. Maternal and fetal characteristics were summarized. The primary outcome of interest was birthweight discordance (BWD) ≥20%, and secondary outcomes included small for gestational age (SGA) as a binary outcome and mean value and absolute difference in birthweight as continuous outcomes. Student’s t test and the chi-square test were used for univariate analyses, while multivariate regressions were used to adjust for confounders. General estimated equation (GEE) models were used to address the correlation between fetuses when assessing SGA. A total of 866 eligible subjects were included in the analysis. In total, 460 pregnancies had placentas with different locations, and 406 had placentas with same locations. The gestational age at delivery was slightly younger in the same placental location group than in the different placental location group (35.8 ± 0.1 vs. 36.1 ± 0.1 weeks, P = 0.067). Other maternal and fetal characteristics were comparable between the two study groups. There was no significant difference in BWD ≥20% (aOR = 1.06; 95% CI: 0.71–1.59) or SGA (aOR = 1.32; 95% CI: 0.76–2.28) between the same and different placental location groups. Neither the mean value nor the absolute difference in birth weight was associated with placental location combination (P = 0.478 and P = 0.162, respectively). In conclusion, discordant birthweight is not affected by same location of diamniotic-dichorionic placentas.