Placental Location and the Development of Hypertensive Disorders of Pregnancy

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.

Placenta location, a prognostic determinant for the incidence of preeclampsia

BACKGROUND

Preeclampsia is one of the complications of pregnancy with uncertain etiology. Nevertheless, it is believed that the condition may arise due to abnormal trophoblastic invasion, resulting in vascular remodeling and increased resistance in the spiral arteries. It is assumed that the location of the placenta might have contributed to the formation of trophoblastic invasion and further placental supply. The current study aims to investigate the association of placental location with the incidence of preeclampsia.

METHODS

The current case-control study was conducted on 206 primigravid pregnant woman undergone routine screening ultrasonography study between 14 and 26 gestational weeks to determine the location of the placenta (anterior, posterior, or lateral). The pregnant women were categorized as cases that met the criteria of high-risk for preeclampsia (n = 106) or the controls (n = 100).

RESULTS

Logistic regression analysis identified increased age (OR: 1.047, 95% CI: 1.02-1.07, PPP-value = 0.033), BMI > 25 kg/m² (OR: 4.61, 95% CI: 1.02-10.02, PPP-value = 0.038), and anterior placental location (OR: 2.79, 95% CI: 1.08-9.43, PPP-value = 0.038) as significant predictors of preeclampsia. Posterior placental location was initially associated with preeclampsia (PPP-value = 0.049), but this association was not robust and may reflect random variation.

CONCLUSION

This study identified anterior placental location, increased maternal age, and BMI above 25 kg/m² as significant predictors of preeclampsia. These findings suggest that healthcare providers should closely monitor pregnant women with anteriorly located placentas, advanced age, or elevated BMI. Regular blood pressure monitoring and urine protein screening for individuals with anterior placental location could facilitate early diagnosis and management of preeclampsia. While posterior placental location showed a potential association, it was less consistent, and further research is needed to confirm its role.

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.

Comparison of Placental Location on Ultrasound in Preeclampsia and Normotensive Pregnancy in Third Trimester

Background

Hypertensive disorders in pregnancy account for 15%-20% maternal and 20%-25% perinatal mortality. There is interest in predicting preeclampsia (PE) early in pregnancy to reduce PE and its subsequent complications. There is no cheap and easily available, reliable predictor for PE. Some studies have shown that the lateral location of placenta is associated with adverse pregnancy outcomes due to PE. The lateral placenta is yet to be proven as a strong predictor of PE to initiate preventive measures. Placental localization can be easily done on routine ultrasonography during pregnancy. In the light of these observations, a prospective study was done to study any association between PE and placental location by ultrasound in third trimester. Research Question: Is there any association between placental location on ultrasound and preeclampsia in third trimester? The objective is to study association between location of placenta and preeclampsia and compare placental location in normotensive pregnancies with that in PE in third trimester.

Methods

A prospective comparative, case-control, observational study was conducted in the Department of Obstetrics and Gynecology at North DMC Medical College and Hindu Rao Hospital, Delhi, India, from August 2019 to April 2020. The study population included 200 pregnant women with singleton pregnancy in third trimester, without any medical disorders such as diabetes mellitus, hypertension, renal disease, cardiac disease, and coagulation disorder or smoking. One hundred women had preeclampsia and 100 were normotensive controls. Ultrasound was done after filling F form as per the Government of India guidelines to rule out sex determination, and placenta was localized by ultrasound. Placenta was classified as central when it was equally distributed between the right and left sides of the uterus irrespective of anterior, posterior, or fundal position and lateral when 75% or more of the placental mass was on one side of the midline. Placental location was compared in hypertensive and normotensive pregnancies.

Results

Out of the total 200 women, 152 (76%) had central and 48 (24%) had lateral placenta. Ninety-two percent of controls and 60% of cases had central placenta. Forty percent of cases and only 8% normotensive women had lateral placenta. Lateral placenta was five times more frequent in presence of PE as compared to normotensive controls. Out of 152 women with central placenta, 92 (60.5%) women were normotensive but with lateral placenta, only 8 (16.7%) had normal blood pressure. PE was present in 83% of women with lateral placenta and in only 39.47% with central placenta. This difference was statistically significant as P < 0.0001 as per Chi-square test. This reflects a significant association between lateral position of placenta and occurrence of PE. As per odds ratio (0.1304) patients without lateral placenta had 90% protection against preeclampsia.

Conclusion

Central placenta is more common than lateral placenta. Lateral placenta is seen five times more frequently among hypertensive women and this difference is statistically significant. The absence of lateral placenta provides 90% protection against PE but the severity of PE was not affected by placental location..

The model of screening for preeclampsia in the second and third trimesters of gestation

<b>Purpose:</b> Preeclampsia (PE) is a specific syndrome of multiple organ insufficiency in case of pregnancy, which is included in the panel of major obstetric syndromes and is among the main causes of maternal morbidity and mortality in the whole world.<br /> <b>Material and methods</b>: We conducted a prospective cohort study of 91 pregnant women to evaluate the effectiveness of integrated use of maternal risk factors (2019 International Federation of Gynecology and Obstetrics recommendations), placenta location (ultrasound at 18-20 weeks of gestation), and serum cystatin C (at 18-36 weeks of gestation) in screening for pe in the second and third trimesters of gestation.<br /> <b>Results: </b>In the subgroup of pregnant women with cystatin C levels greater than 1.0 mg/L (27 women), PE developed in 26 women, which is 96.29% in percentage terms. When calculating GFR for cystatin C in a group with PE there was a significant violation of the renal filtration system -52.46±2.08 (95% CI, 48.39-56.54), while in healthy group the indicator is within normal limits -97.6±1.64 (95% CI, 94.38-100.82). In the analysis of the ratio of cystatin C levels more than 1.0 mg / l and the development of PE, a sensitivity of 98.46%, specificity of 100% and accuracy of 98.9%, p&lt;0.001.<br /> <b>Conclusions: </b>The data show that the combined model of maternal factors, ultrasound of the placenta and serum cystatin C, is prognostically effective in pregnant women in the second and third trimesters of gestation and is a reliable marker for the development of pe.

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.

Lateral placentation and adverse perinatal outcomes

Lateral placentation may compromise placental perfusion, and we aimed to assess whether it impacts pregnancy outcomes. This single-center retrospective study included 1203 singleton pregnancies, categorized into two groups according to placental location. Women with lateral placenta had significantly higher risk of preterm birth <37 weeks (aOR 2.99) and <34 weeks (aOR 3.92), and gestational diabetes (aOR 2.72), compared to women with central placenta. Mean birth weight and small for gestational age (SGA) rates were similar between groups. Our findings suggest that lateral placenta may be associated with increased risk for preterm birth but not for SGA.

[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.

Uterine artery pulsatility index for the prediction of obstetrical complications in preterm prelabor rupture of membranes

Introduction: Abnormal uterine artery Doppler studies have been associated with an increased risk of preeclampsia, fetal growth restriction (FGR), placental abruption, and fetal demise. These obstetrical complications can affect pregnancies with preterm prelabor rupture of membranes (PPROM). Therefore, our objective was to assess the prediction accuracy of the uterine artery pulsatility index (UtAPI) to detect these complications in pregnancies with PPROM.Materials and methods: This was a prospective study of pregnancies complicated by PPROM from October 2015 to May 2018. We included mothers aged 13-46 years old with singleton pregnancies from 23 to 36 + 6 weeks with PPROM. Those without UtAPI measurements and complex fetal anomalies were excluded. Our primary outcome was a composite of obstetrical complications, defined as having one or more of the following: gestational hypertension or preeclampsia, placenta abruption, FGR, or fetal demise. The UtAPI was obtained at the time of enrollment. Logistic regression models with receiver operating curves were used to determine the predictive value of the UtAPI for obstetrical complications. A p value of <.05 was considered significant.Results: A total of 103 patients met inclusion criteria, of those 37 (36%) developed an obstetrical complication (FGR = 22 (21.5%); preeclampsia or gestational hypertension = 9 (9%); placental abruption = 8 (8%); fetal demise = 1 (1%)). Six mothers had more than one complication. The UtAPI was not a statistically significant predictor of a composite of obstetrical complications (AUC = 0.61; p = .07) or for any of the individual complications studied.Conclusions: The UtAPI appears to have limited clinical value for the prediction of obstetrical complications previously associated with abnormal uterine artery Doppler indices in pregnancies with PPROM. Larger and more diverse studies are needed to corroborate our findings.Brief rationale: An accurate prediction for adverse outcomes in patients with PPROM may help identify those that may benefit from increased surveillance protocols.

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.