Gestational thrombocytopenia: a case-control study of over 3,500 pregnancies

Genetic basis of pregnancy-associated decreased platelet counts and gestational thrombocytopenia

ABSTRACT

Platelet count reduction occurs throughout pregnancy, with 5% to 12% of pregnant women being diagnosed with gestational thrombocytopenia (GT), characterized by a more marked decrease in platelet count during pregnancy. However, the underlying biological mechanism behind these phenomena remains unclear. Here, we used sequencing data from noninvasive prenatal testing of 100 186 Chinese pregnant individuals and conducted, to our knowledge, the hitherto largest-scale genome-wide association studies on platelet counts during 5 periods of pregnancy (the first, second, and third trimesters, delivery, and the postpartum period) as well as 2 GT statuses (GT platelet count < 150 × 109/L and severe GT platelet count < 100 × 109/L). Our analysis revealed 138 genome-wide significant loci, explaining 10.4% to 12.1% of the observed variation. Interestingly, we identified previously unknown changes in genetic effects on platelet counts during pregnancy for variants present in PEAR1 and CBL, with PEAR1 variants specifically associated with a faster decline in platelet counts. Furthermore, we found that variants present in PEAR1 and TUBB1 increased susceptibility to GT and severe GT. Our study provides insight into the genetic basis of platelet counts and GT in pregnancy, highlighting the critical role of PEAR1 in decreasing platelet counts during pregnancy and the occurrence of GT. Those with pregnancies carrying specific variants associated with declining platelet counts may experience a more pronounced decrease, thereby elevating the risk of GT. These findings lay the groundwork for further investigation into the biological mechanisms and causal implications of GT.

How I treat thrombocytopenia in pregnancy

ABSTRACT

Thrombocytopenia is a common hematologic abnormality in pregnancy, encountered in ∼10% of pregnancies. There are many possible causes, ranging from benign conditions that do not require intervention to life-threatening disorders necessitating urgent recognition and treatment. Although thrombocytopenia may be an inherited condition or predate pregnancy, most commonly it is a new diagnosis. Identifying the responsible mechanism and predicting its course is made challenging by the tremendous overlap of clinical features and laboratory data between normal pregnancy and the many potential causes of thrombocytopenia. Multidisciplinary collaboration between hematology, obstetrics, and anesthesia and shared decision-making with the involved patient is encouraged to enhance diagnostic clarity and develop an optimized treatment regimen, with careful consideration of management of labor and delivery and the potential fetal impact of maternal thrombocytopenia and any proposed therapeutic intervention. In this review, we outline a diagnostic approach to pregnant patients with thrombocytopenia, highlighting the subtle differences in presentation, physical examination, clinical course, and laboratory abnormalities that can be applied to focus the differential. Four clinical scenarios are presented to highlight the pathophysiology and treatment of the most common causes of thrombocytopenia in pregnancy: gestational thrombocytopenia, preeclampsia, and immune thrombocytopenia.

Thrombocytopenia and associated factors among pregnant women attending antenatal care at Hiwot Fana Comprehensive Specialized Hospital, Eastern Ethiopia: A cross-sectional study

Thrombocytopenia (TCP) is the second most common hematological change during pregnancy and is considered as a major source of maternal and neonatal morbidity and mortality. Despite its effects to morbidity and mortality, it is frequently ignored or disregarded, particularly in resource-limited nations. Thus, the purpose of this study was to determine the prevalence of thrombocytopenia and associated factors among pregnant women attending antenatal care at Hiwot Fana Comprehensive Specialized University Hospital, Eastern Ethiopia from June 20 to August 30, 2022. A hospital-based cross-sectional study was conducted among 199 pregnant women selected through a systematic sampling technique. Ethical approval was obtained from the Ethics Review Committee of Haramaya University. Data related to sociodemographic and reproductive variables were collected using structured questionnaires. Four milliliters of venous blood were collected from each study participant and a complete blood cell count was determined using UniCel DxH 800 hematology analyzer. Logistic regression analysis was done to assess the association between TCP and independent variables and P < .05 was considered statistically significant. In this study, the prevalence of TCP was 14.1% (95% CI: 9.6-19.7). Of them, 10 (35.7%), 12 (42.9%), and 4 (21.4%) had mild, moderate, and severe TCP, respectively. Having more than 3 children (adjusted odds ratio, AOR = 7.90, 95% CI: 2.60, 24.3), no antenatal care follow-up (AOR = 7.90, 95% CI: 2.40-26.2), being in the second and third trimester (AOR = 6.90, 95% CI: 1.70, 28.9 and AOR = 5.04, 95% CI: 1.12, 22.7, respectively), and history of heavy menstrual bleeding (AOR = 4.03, 95% CI: 1.25, 13.1) were significantly associated with TCP. TCP is a public health problem among pregnant women in the study area. Having more than 3 children, lack of antenatal care follow-up, being in the second and third trimesters, and having history of heavy menstrual bleeding was significantly associated with TCP. As a result, regular platelet count monitoring and appropriate intervention approaches based on identified predictors should be explored to mitigate adverse outcomes in pregnant women.

Recurrent Gestational Thrombocytopenia Affecting Four Consecutive Pregnancies: A Case Report

Gestational thrombocytopenia is the commonest cause of thrombocytopenia in pregnancy, accounting for 70-80% of cases. It is a benign condition that recovers completely in the postpartum period. Although the cause is not fully understood, it is thought that pregnancy-related hemodilution and increased platelet consumption play a significant contributory role. Several life-threatening causes of thrombocytopenia in pregnancy make up the remaining 20-30% of cases. There are reports of recurrence of GT in women, but not many case reports document more than three consecutive episodes. We present a case of a young woman who had gestational thrombocytopenia during the third trimester of her four consecutive pregnancies, followed by complete recovery after each pregnancy. We ruled out other sinister and life-threatening causes of thrombocytopenia in pregnancy. During her four consecutive pregnancies, her platelet count fell below normal at the beginning of the third trimester, with a nadir towards the end. The other hematological indices, generally used as markers of hemodilution, remained in the normal pregnancy-specific reference range during each of her four pregnancies. This case argues against pregnancy-related hemodilution being a major factor in gestational thrombocytopenia. A systematic approach is paramount when differentiating the several causes of thrombocytopenia in pregnancy.

Maternal platelets at the first trimester maternal-placental interface - Small players with great impact on placenta development

In human pregnancy, maternal platelet counts decrease with each trimester, reaching a reduction by approximately ten percent at term in uncomplicated cases and recover to the levels of the non-pregnant state a few weeks postpartum. The time when maternal platelets start to occur in the early human placenta most likely coincides with the appearance of loosely cohesive endovascular trophoblast plugs showing capillary-sized channels by mid first trimester. At that time, platelets accumulate in intercellular gaps of anchoring parts of trophoblast columns and start to adhere to the surface of placental villi and the chorionic plate. This is considered as normal process that contributes to placenta development by acting on both the extravillous- and the villous trophoblast compartment. Release of platelet cargo into intercellular gaps of anchoring cell columns may affect partial epithelial-to-mesenchymal transition and invasiveness of extravillous trophoblasts as well as deposition of fibrinoid in the basal plate. Activation of maternal platelets on the villous surface leads to perivillous fibrin-type fibrinoid deposition, contributing to the shaping of the developing placental villi and the intervillous space. In contrast, excess platelet activation at the villous surface leads to deregulation of the endocrine activity, sterile inflammation and local apoptosis of the syncytiotrophoblast. Platelets and their released cargo are adapted to pregnancy, and may be altered in high-risk pregnancies. Identification of different maternal platelet subpopulations, which show differential procoagulant ability and different response to anti-platelet therapy, are promising new future directions in deciphering the role of maternal platelets in human placenta physiology.