Chorioamnionitis in pregnancy: a comparative study of HIV-positive and HIV-negative parturients

Placental pathology in women with HIV

Recognizing the importance of placental features and their unique functions can provide insight into maternal health, the uterine environment during the course of pregnancy, birth outcomes and neonatal health. In the context of HIV and antiretroviral therapy (ART), there have been great strides in the prevention of mother to child transmission of HIV. However, there is still paucity of data on the impact of HIV/ART exposure on placental pathology and studies available only examine specific patterns of placental injury, further justifying the need for a more defined and comprehensive approach to the differential diagnoses of HIV/ART-exposed placentae. The purpose of this review is to consolidate findings from individual studies that have been reported on patterns of placental injury in the context of HIV/ART exposure. In both the pre- and post-ART eras HIV and/or ART has been associated with placental injury including maternal vascular malperfusion as well as acute and chronic inflammation. These patterns of injury are further associated with adverse birth outcomes including preterm birth and current evidence suggests an association between poor placental function and compromised fetal development. With the ever increasing number of pregnant women with HIV on ART, there is a compelling need for full incorporation of placental diagnoses into obstetric disease classification. It is also important to take into account key elements of maternal clinical history. Lastly, there is a need to standardize the reporting of placental pathology in order to glean additional insight into the elucidation of HIV/ART associated placental injury.

HIV, placental pathology and birth outcomes - a brief overview

The spectrum of placental pathology in human immunodeficiency virus (HIV) is vast. Features observed are not only limited to the effects of the virus itself but may include that of coinfections such as tuberculosis and syphilis. The presence of other comorbidities and changes as a result of antiretroviral therapy may further confound the histologic findings. There is a paucity of unbiased information of the effects of maternal HIV on the placenta and how these changes relate to birth outcomes. Antiretroviral therapy, now in widespread use, has altered the course of maternal HIV disease and it is unknown whether this has altered the pathophysiology of HIV on the placenta. HIV-associated placental findings that have been most well described include acute chorioamnionitis, low placental weight and maternal vascular malperfusion, with a tendency towards lower rates of chronic villitis.

The prevalence of histologic acute chorioamnionitis among HIV infected pregnant women in Uganda and its association with adverse birth outcomes

BACKGROUND

Preterm birth (PTB) is a leading cause of neonatal mortality and longer-term morbidity. Acute chorioamnionitis (ACA) is a common cause of PTB, however, there are limited data on the prevalence of ACA and its association with PTB in resource limited settings.

METHODS

Data and samples came from a clinical trial evaluating novel strategies for the prevention of malaria in HIV infected pregnant women in Uganda. Women were enrolled between 12-28 weeks of gestation and followed through delivery. For each placenta delivered, three placental tissue types (membrane roll, umbilical cord and chorionic plate/villous parenchyma) were collected. Slides were assessed for diagnosis of maternal and fetal ACA by microscopic evaluation of neutrophilic infiltration using a standardized grading scale. The primary outcomes were PTB (<37 weeks), low birth weight (LBW, <2500 grams), and small-for-gestational age (SGA, birth weight <10th percentile for age). Univariate and multivariate logistic regression were used to estimate associations between 1) maternal characteristics (age, education, wealth, gravidity, gestational age at enrollment, placental malaria, anti-malarial prophylaxis treatment regimen, HIV disease parameters) and ACA, and 2) associations between ACA and adverse birth outcomes.

FINDINGS

A total of 193 placentas were included in the analysis. The prevalence of maternal and fetal ACA was 44.5% and 28.0%, respectively. HIV infected women between 28-43 years of age had a higher risk of maternal ACA compared to those between 17-21 years of age (50.9% vs. 19.1%; aOR = 4.00 (1.10-14.5), p = 0.04) and the diagnosis of severe maternal ACA was associated with a significantly higher risk of PTB (28.6% vs. 6.0%; aOR = 6.04 (1.87-19.5), p = 0.003), LBW (33.3% vs. 9.4%; aOR = 4.86 (1.65-14.3); p = 0.004), and SGA (28.6% vs. 10.1%; aOR = 3.70 (1.20-11.4), p = 0.02). No maternal characteristics were significantly associated with fetal ACA and the diagnosis of fetal ACA was not associated with adverse birth outcomes.

CONCLUSIONS

Histological evidence of severe maternal ACA was associated with an increased risk of PTB, LBW, and SGA in HIV infected, pregnant Ugandan women.