A population-based study of race-specific risk for placental abruption

Risks of Placental Abruption and Preterm Delivery in Patients Undergoing Assisted Reproduction

Importance

Patients using assisted reproductive technology (ART) may need additional counseling about the increased risks of placental abruption and preterm delivery. Further investigation into the potential additive risk of ART and placental abruption is needed.

Objective

To ascertain the risk of placental abruption in patients who conceived with ART and to evaluate if placental abruption and ART conception are associated with an increased risk of preterm delivery (<37 weeks' gestation) over and above the risks conferred by each factor alone.

Design, Setting, and Participants

This cross-sectional study used data from the National Inpatient Sample, which includes data from all-payer hospital inpatient discharges from 48 states across the US. Participants included women aged 15 to 54 years who delivered from 2000 through 2019. Data were analyzed from January 17 to April 18, 2024.

Exposures

Pregnancies conceived with ART.

Main Outcomes and Measures

Risks of placental abruption and preterm delivery in ART conception compared with spontaneous conceptions. Associations were expressed as odds ratios (ORs) and 95% CIs derived from weighted logistic regression models before and after adjusting for confounders. The relative excess risk due to interaction (RERI) of the risk of preterm delivery based on ART conception and placental abruption was also assessed.

Results

Of 78 901 058 deliveries, the mean (SD) maternal age was 27.9 (6.0) years, and 9 212 117 patients (11.7%) were Black individuals, 14 878 539 (18.9%) were Hispanic individuals, 34 899 594 (44.2%) were White individuals, and 19 910 807 (25.2%) were individuals of other races and ethnicities. Of the total hospital deliveries, 98.2% were singleton pregnancies, 68.8% were vaginal deliveries, and 52.1% were covered by private insurance. The risks of placental abruption among spontaneous and ART conceptions were 11 and 17 per 1000 hospital discharges, respectively. After adjusting for confounders, the adjusted OR (AOR) of placental abruption was 1.42 (95% CI, 1.34-1.51) in ART pregnancies compared with spontaneous conceptions, with increased odds in White women (AOR, 1.42; 95% CI, 1.31-1.53) compared with Black women (AOR, 1.16; 95% CI, 0.93-1.44). The odds of preterm delivery were significantly higher in pregnancies conceived by ART compared with spontaneous conceptions (AOR, 1.46; 95% CI, 1.42-1.51). The risk of preterm delivery increased when patients had both ART conception and placental abruption (RERI, 2.0; 95% CI, 0.5-3.5).

Conclusions and Relevance

In this cross-sectional study, patients who conceived using ART and developed placental abruption had a greater risk of preterm delivery compared with spontaneous conception without placental abruption. These findings have implications for counseling patients who seek infertility treatment and obstetrical management of ART pregnancies.

Racial variations of adverse perinatal outcomes: A population-based retrospective cohort study in Ontario, Canada

Introduction

Racial differences in adverse maternal and birth outcomes have been studied in other countries, however, there are few studies specific to the Canadian population. In this study, we sought to examine the inequities in adverse perinatal outcomes between Black and White pregnant people in Ontario, Canada.

Methods

We conducted a population-based retrospective cohort study that included all Black and White pregnant people who attended prenatal screening and had a singleton birth in any Ontario hospital (April 1^st, 2012-March 31^st, 2019). Poisson regression with robust error variance models were used to estimate the adjusted relative risks of adverse perinatal outcomes for Black people compared with White people while adjusting for covariates.

Results

Among 412,120 eligible pregnant people, 10.1% were Black people and 89.9% were White people. Black people were at an increased risk of gestational diabetes mellitus, preeclampsia, placental abruption, preterm birth (<37, <34, <32 weeks), spontaneous preterm birth, all caesarean sections, emergency caesarean section, low birth weight (<2500g, <1500g), small-for-gestational-age (<10th percentile, <3^rd percentile) neonates, 5-minute Apgar score <4 and <7, neonatal intensive care unit admission, and hyperbilirubinemia requiring treatment but had lower risks of elective caesarean section, assisted vaginal delivery, episiotomy, 3rd and 4th degree perineal tears, macrosomia, large-for-gestational-age neonates, and arterial cord pH≤7.1, as compared with White people. No difference in risks of gestational hypertension and placenta previa were observed between Black and White people.

Conclusion

There are differences in several adverse perinatal outcomes between Black and White people within the Ontario health care system. Findings might have potential clinical and health policy implications, although more studies are needed to further understand the mechanisms.

Disparities in Adverse Maternal Outcomes Among Five Race and Ethnicity Groups

Background: Racial/ethnic disparities are evident in adverse maternal health outcomes, but they are shifting due to interventions, initiatives, changing demographics, and the prevalence of preexisting conditions. This study examined the current racial/ethnic disparities in adverse maternal outcomes. Materials and Methods: In a cross-sectional study, the International Classification of Diseases-10 codes for the principal diagnosis and secondary diagnoses were retrieved from the National Inpatient Sample database (2016-2018). A weighted multiple logistic regression model assessed disparities in seven adverse maternal outcomes, including preterm labor, gestational hypertension (GHTN) and diabetes, premature rupture of membranes (PRM), infection of the amniotic cavity (INFAC), placental abruption, and postpartum hemorrhage (PPH). A weighted linear regression model assessed disparities in a composite variable of maternal outcomes. A maternal-specific comorbidity index assessed risk adjustment, and other clinical, sociodemographic, and hospital factors were considered. Results: A total of 2,211,345 pregnancies were included. Preterm labor, GHTN, and placental abruption had the highest raw rate among Black women compared to all races. After adjusting for control variables in the regression analysis, these adverse outcomes also showed the highest odds ratio (OR) among Black women compared to White women (the reference group). Gestational diabetes, PRM, and INFAC had the highest raw rate among Asians/Pacific Islanders (PIs). After adjusting for control variables, these adverse outcomes also showed the highest OR among Asians/PIs compared to White women. The OR for PPH was the highest for Native Americans compared to White women. Furthermore, results of the composite outcome variable indicated that all minority groups experienced the overall poorer maternal outcome than White women. Conclusions: Overall, all four minority women had higher raw rates and also odds of experiencing the studied adverse outcomes than White women. Existing efforts should be strengthened to continue reducing racial/ethnic disparities in adverse maternal outcomes.

Placental abruption in immigrant women in Norway: A population-based study

INTRODUCTION

Placental abruption is a serious complication in pregnancy. Its incidence varies across countries, but the information of how placental abruption varies in immigrant populations is limited. The aims of this study were to estimate the incidence of placental abruption in immigrant women compared with non-immigrants by maternal country and region of birth, reason for immigration, and length of residence.

MATERIAL AND METHODS

We conducted a nationwide population-based study using data from the Medical Birth Registry of Norway and Statistics Norway (1990-2016). The study sample included 1 558 174 pregnancies, in which immigrant women accounted for 245 887 pregnancies and 1 312 287 pregnancies were to non-immigrants. Crude and adjusted odds ratios with 95% CI for placental abruption in immigrant women compared with non-immigrants were estimated by logistic regression with robust standard error estimations (accounting for within-mother clustering). Adjustment variables included year of birth, maternal age, parity, multiple pregnancies, chronic hypertension, and level of education.

RESULTS

The incidence of placental abruption decreased during the study period for both immigrants (from 0.68% to 0.44%) and non-immigrants (from 0.80% to 0.34%). Immigrant women from sub-Saharan Africa had an adjusted odds ratio of 1.35 (95% CI 1.15-1.58) compared with non-immigrants for placental abruption, whereas immigrant women from Ethiopia had an adjusted odds ratio of 2.39 (95% CI 1.67-3.41). We found a small variation in placental abruption incidence by other countries or regions of birth, length of residence, and reason for immigration.

CONCLUSIONS

Immigrant women from sub-Saharan Africa, especially Ethiopia, have increased odds for placental abruption when giving birth in Norway. Reason for immigration and length of residence had little impact on the incidence of placental abruption.

Placental Abruption as a Risk Factor for Heart Failure

Complications of pregnancy present an opportunity to identify women at high risk of cardiovascular disease (CVD). Placental abruption is a severe and understudied pregnancy complication, and its relationship with CVD is poorly understood. The California Healthcare Cost and Utilization Project database was used to identify women with hospitalized pregnancies in California between 2005 and 2009, with follow-up through 2011. Pregnancies, exposures, covariates, and outcomes were defined by International Classification of Diseases Ninth Revision codes. Cox proportional-hazards regression was used to examine the association between placental abruption and myocardial infarction (MI), stroke, and heart failure (HF). Multivariate models controlling for age, race, medical co-morbidities, pregnancy complications, psychiatric and substance use disorders, and socioeconomic factors were employed. Among over 1.5 million pregnancies, placental abruption occurred in 14,881 women (1%). Median follow-up time from delivery to event or censoring was 4.87 (interquartile range 3.54 to 5.96) years. In unadjusted models, placental abruption was associated with risk of HF, but not MI or stroke. In fully-adjusted models, placental abruption remained significantly associated with HF (Hazard ratio 1.44; 95% confidence interval 1.09 to 1.90). Among women with placental abruptions, hypertensive disorders of pregnancy and preterm birth respectively modified and mediated the association between placental abruption and HF. In conclusion, placental abruption is a risk factor for HF, particularly in women who also experience hypertensive disorders of pregnancy and preterm birth. Placental abruption is a specific adverse pregnancy outcome associated with risk of HF.

Maternal risk factors and neonatal outcomes in placental abruption among patients with equal access to health care

INTRODUCTION

Placental abruption complicates 1% of pregnancies, and is associated with significant morbidity and mortality. The objective was to examine risk factors and outcomes in pregnancies complicated by abruption in a health care system with equal access to care.

METHODS

This was a retrospective cohort study of all deliveries at Walter Reed National Military Medical Center (WRNMMC) between 1 January 2014 and 1 June 2017. The primary outcome was maternal factors that influenced abruption. The secondary outcome evaluated the neonatal outcomes after abruption.

RESULTS

A total of 4351 patients delivered at WRNMMC and met the inclusion criteria. 52 patients (1.2%) had a pathology confirmed abruption. There was an association with smoking (p < .05; OR 4.25) and African American race (p = .005). Neonatal variables demonstrated an association between abruption and gestational age at delivery, low birth weight, Apgar scores, NICU admissions, and fetal demise all with p < .005.

CONCLUSIONS

Our results demonstrate an association between both smoking and African American race with placental abruption. Unlike previous studies, there were no barriers to access to care. Further, there was no association with age, hypertension, diabetes, autoimmune disease, or trauma. Results did reaffirm an association between abruption and preterm birth, low birth weight, lower Apgars, NICU admissions, and fetal demise.PrécisIn a medical system with no barriers to access to care, maternal risk factors and neonatal outcomes associated with placental abruptions were investigated in over 4300 deliveries.

The Role of Extremes in Interpregnancy Interval in Women at Increased Risk for Adverse Obstetric Outcomes Due to Health Disparities: A Literature Review

Background:

The interpregnancy interval (IPI) defines the time between two consecutive gestations. In the general population, women with IPIs that fall outside the recommended 18-24 month range appear to be at modestly increased risk for adverse obstetric outcomes.

Objective:

The aim of this review was to assess the impact of extremes in IPI in populations with an increased baseline risk for adverse obstetric outcomes due to disparities in health and health care, including racial and ethnic groups, adolescents, and those of lower socioeconomic status.

Methods:

We conducted a MEDLINE/Pubmed literature search in February 2016. Identified articles were reviewed and assigned a level of evidence.

Results:

The 24 studies included in our final review were mainly retrospective with considerable heterogeneity in definitions and outcomes that prevented a quantitative meta-analysis.

Conclusion:

The results of our review suggest that at-risk populations may have an increased frequency of shortened IPIs though the impact appears to be moderate and inconsistent. There was insufficient evidence to draw meaningful conclusions regarding a prolonged IPI or the effect of interventions. Based on the current literature, under-served populations are more likely to have a shortened IPI which increased the incidence of prematurity and low birth weight in some groups though the effect on additional obstetric outcomes is difficult to assess

Rare mutations and potentially damaging missense variants in genes encoding fibrillar collagens and proteins involved in their production are candidates for risk for preterm premature rupture of membranes

Preterm premature rupture of membranes (PPROM) is the leading identifiable cause of preterm birth with ~ 40% of preterm births being associated with PPROM and occurs in 1% - 2% of all pregnancies. We hypothesized that multiple rare variants in fetal genes involved in extracellular matrix synthesis would associate with PPROM, based on the assumption that impaired elaboration of matrix proteins would reduce fetal membrane tensile strength, predisposing to unscheduled rupture. We performed whole exome sequencing (WES) on neonatal DNA derived from pregnancies complicated by PPROM (49 cases) and healthy term deliveries (20 controls) to identify candidate mutations/variants. Genotyping for selected variants from the WES study was carried out on an additional 188 PPROM cases and 175 controls. All mothers were self-reported African Americans, and a panel of ancestry informative markers was used to control for genetic ancestry in all genetic association tests. In support of the primary hypothesis, a statistically significant genetic burden (all samples combined, SKAT-O p-value = 0.0225) of damaging/potentially damaging rare variants was identified in the genes of interest-fibrillar collagen genes, which contribute to fetal membrane strength and integrity. These findings suggest that the fetal contribution to PPROM is polygenic, and driven by an increased burden of rare variants that may also contribute to the disparities in rates of preterm birth among African Americans.

Body Mass Index as a Measure of Obesity: Racial Differences in Predictive Value for Health Parameters During Pregnancy

BACKGROUND

As a measure of obesity, body mass index (BMI; kg/m²) is an imperfect predictor of health outcomes, particularly among African Americans. However, BMI is used to guide prenatal care. We examined racial differences in the predictive value of maternal BMI for physiologic correlates of obesity, serum interleukin (IL)-6 and C-reactive protein (CRP), as well as cesarean section and infant birth weight.

METHODS

One hundred five pregnant women (40 European American, 65 African American) were assessed during the second trimester. BMI was defined as per prepregnancy weight. Electrochemiluminescence and enzyme-linked immunosorbent assays were used to quantify IL-6 and CRP, respectively. Birth outcomes were determined by medical record review.

RESULTS

Women of both races classified as obese had higher serum IL-6 and CRP than their normal-weight counterparts (ps ≤ 0.01). However, among women with overweight, elevations in IL-6 (p < 0.01) and CRP (p = 0.06) were observed among European Americans, but not African Americans (ps ≥ 0.61). Maternal obesity was a significantly better predictor of cesarean section among European Americans versus African Americans (p = 0.03) and BMI was associated with infant birth weight among European Americans (p < 0.01), but not African Americans (p = 0.94). Effects remained after controlling for gestational age at delivery, gestational diabetes, and gestational weight gain as appropriate.

CONCLUSIONS

BMI may be a less valid predictor of correlates of overweight/obesity among African Americans versus European Americans during pregnancy. This should be considered in epidemiological studies of maternal-child health. In addition, studies examining the comparative validity of alternative/complementary measures to define obesity in pregnancy are warranted to inform clinical care.

Compensatory fetal membrane mechanisms between biglycan and decorin in inflammation

Preterm premature rupture of fetal membranes (PPROM) is associated with infection, and is one of the most common causes of preterm birth. Abnormal expression of biglycan and decorin, two extracellular matrix proteoglycans, leads to preterm birth and aberrant fetal membrane morphology and signaling in the mouse. In humans and mice, decorin dysregulation is associated with inflammation in PPROM. We therefore investigated the link between biglycan and decorin and inflammation in fetal membranes using mouse models of intraperitoneal Escherichia coli injections superimposed on genetic biglycan and decorin deficiencies. We assessed outcomes in vivo as well as in vitro using quantitative PCR, Western blotting, and enzyme-linked immunosorbent assays. Our results suggest that biglycan and decorin compensate for each other in the fetal membranes, but lose the ability to do so under inflammation, leading to decreased latency to preterm birth. Furthermore, our findings suggest that biglycan and decorin play discrete roles in fetal membrane signaling pathways during inflammation, leading to changes in the abundance of MMP8 and collagen α1VI, two components of the fetal membrane extracellular matrix that influence the pathophysiology of PPROM. In summary, these findings underline the importance of biglycan and decorin as targets for the manipulation of fetal membrane extracellular matrix stability in the context of inflammation.

Racial/ethnic disparities in maternal morbidities: a statewide study of labor and delivery hospitalizations in Wisconsin

We examined racial/ethnic disparities in maternal morbidities (MM) and the number of MM during labor and delivery among hospital discharges in Wisconsin. We conducted a retrospective cohort study of hospital discharge data for 206,428 pregnant women aged 13-53 years using 2005-2007 Healthcare Cost and Utilization Project State Inpatient Dataset (HCUP-SID) for Wisconsin. After adjustments for covariates, MM (preterm labor, antepartum and postpartum hemorrhage, hypertension in pregnancy, gestational diabetes, membrane-related disorders, infections and 3rd and 4th perineal lacerations) were examined using logistic regression models, and number of MM (0, 1, 2, >2 MM) were examined using multivariable ordered logistic regressions with partial proportional odds models. African-Americans had significantly higher likelihood of infections (OR = 1.74; 95% CI 1.60-1.89), preterm labor (OR = 1.42; 1.33-1.50), antepartum hemorrhage (OR = 1.63; 1.44-1.83), and hypertension complicating pregnancy (OR = 1.39; 1.31-1.48) compared to Whites. Hispanics, Asian/Pacific Islanders, and Native Americans had significantly higher likelihood of infections, postpartum hemorrhage, and gestational diabetes than Whites. Major perineal lacerations were significantly higher among Asian/Pacific Islanders (OR = 1.53; 1.34-1.75). All minority racial/ethnic groups, except Asians, had significantly higher likelihood of having 0 versus 1, 2 or >2 MM, 0 or 1 versus 2 or >2 MM, and 0, 1 or 2 versus >2 MM than white women. Findings show significant racial/ethnic disparities in MM, and suggest the need for better screening, management, and timely referral of these conditions, particularly among racial/ethnic women. Disparities in MM may be contributing to the high infant mortality and adverse birth outcomes among different racial/ethnic groups in Wisconsin.

Abruptio placentae in the baboon (Papio spp.)

INTRODUCTION

Placental abruption is a serious condition that increases perinatal morbidity and mortality. Clinical prevention and treatment options are limited, especially in human preterm deliveries. Knowledge of the mechanisms that keep the placenta in place during pregnancy is critical for developing strategies for the prevention of abruption. Failure of physiological transformation of spiral arteries has been described as a major contributing factor of the placental abruption development. Baboons (Papio spp.) share striking similarities with humans in regard to placental structure, utero-placental blood flow, and fetal development; however, the mode of trophoblast invasion is shallow in baboons. This fact prompted the hypothesis that the incidence of placental abruption will be increased in baboons compared to humans.

MATERIAL AND METHODS

Baboon placentas were collected between 2002 and 2008. Two independent veterinary pathologists evaluated the slides. A certified physician pathologist performed additional histology.

RESULTS

Placental abruption was diagnosed in 22 baboons among 2423 live births during the study period (0.9% prevalence). The most common clinical presentations were fetal demise and vaginal bleeding. The most common pathological findings were intraplacental hemorrhages with or without hematoma formation (86.4%). Other findings consisted of neutrophil infiltration (50%), decidual necrosis (22.7%), decidual vascular congestion and inflammation, villous congestion and retroplacental hemorrhage/hematoma (each 18.2%). These pathologic findings were the same for term and preterm deliveries.

CONCLUSION

This is the first systematic study of placental abruption in non-human primates, analyzing a large colony of baboons. Despite differences in trophoblast invasion, the clinical features observed in placental abruption affecting baboons resembled those reported in humans. The cluster of placental pathological findings in baboons also agreed with clinical reports, but the prevalence of these findings differed between baboons and humans. We discuss a mechanism of anti-abruption forces that offset shallow trophoblast invasion observed in baboons.

Racial and ethnic disparities in United States: stillbirth rates: trends, risk factors, and research needs

As with most adverse health outcomes, there has been long standing and persistent racial and ethnic disparity for stillbirth in the United States. In 2005, the stillbirth rate (fetal deaths ≥ 20 weeks' gestation per 1000 fetal deaths and live births) for non-Hispanic blacks was 11.13 compared with 4.79 for non-Hispanic whites. Rates were intermediate for American Indian or Alaska Natives (6.17) and Hispanics (5.44). There is racial disparity for both early (< 28 weeks' gestation) and late stillbirths. We review available data regarding risk factors for stillbirth with a focus on those factors that are more prevalent in certain racial/ethnic groups and those factors that appear to have a more profound effect in certain racial/ethnic groups. Although many factors, including genetics, environment, stress, social issues, access to and quality of medical care and behavior, contribute to racial disparity in stillbirth, the reasons for the disparity remain unclear. Knowledge gaps and recommendations for further research and interventions intended to reduce racial disparity in stillbirth are highlighted.

Evidence of placental haemorrhage and preterm delivery

OBJECTIVE

To evaluate evidence of placental haemorrhage (PH) obtained through maternal interviews, patient charts and placental pathology examinations as potential indicators of a 'bleeding pathway' to preterm delivery (PTD).

DESIGN

Prospective cohort.

SETTING

Fifty-two clinics in five communities in Michigan, USA (1998-2004).

POPULATION

A subset (n = 996) of cohort participants with complete placental pathology data.

METHODS

First-trimester bleeding and placental abruption were ascertained by mid-trimester interviews and chart review, respectively. Disc-impacting blood clot was defined as a gross placental examination finding of a blood clot impacting adjacent tissue. Microscopic haemorrhage was defined as 'high' (top quintile) scores on an aggregate measure of placental pathology findings suggestive of atypical maternal vessel haemorrhage. These four PH indicators were compared with one another and with risk of PTD assessed by logistic regression analyses.

MAIN OUTCOME MEASURES

Preterm delivery and PTD subtypes (i.e. <35 weeks, 35-36 weeks; spontaneous, medically indicated) compared with term deliveries.

RESULTS

Placental abruption cases had 2.3-fold to 5.5-fold increased odds of the other three PH indicators. Disc-impacting blood clots and microscopic haemorrhage were associated with one another (odds ratio [OR] = 4.6), but not with first-trimester bleeding. In a multivariable model that included all four PH indicators and confounders, risk of PTD < 35 weeks was elevated with first-trimester bleeding (OR = 1.9 [1.0, 3.4]), placental abruption (OR = 5.2 [1.7, 16.2]), disc-impacting blood clots (OR = 2.3 [1.0, 5.0]) and microscopic haemorrhage (OR = 2.4 [1.4, 4.2]).

CONCLUSIONS

Multiple clinical and subclinical PH indicators are associated with PTD, particularly early PTD.

What causes racial disparities in very preterm birth? A biosocial perspective

Very preterm birth (<32 weeks' gestation) occurs in approximately 2% of livebirths but is a leading cause of infant mortality and morbidity in the United States. African-American women have a 2-fold to 3-fold elevated risk compared with non-Hispanic white women for reasons that are incompletely understood. This paper reviews the evidence for the biologic and social patterning of very preterm birth, with attention to leading hypotheses regarding the etiology of the racial disparity. A systematic review of the literature in the MEDLINE, CINAHL, PsycInfo, and EMBASE indices was conducted. The literature to date suggests a complex, multifactorial causal framework for understanding racial disparities in very preterm birth, with maternal inflammatory, vascular, or neuroendocrine dysfunction as proximal pathways and maternal exposure to stress, racial differences in preconceptional health, and genetic, epigenetic, and gene-environment interactions as more distal mediators. Interpersonal and institutionalized racism are mechanisms that may drive racially patterned differences. Current literature is limited in that research on social determinants and biologic processes of prematurity has been generally disconnected. Improved etiologic understanding and the potential for effective intervention may come with better integration of these research approaches.