China: The researchers in a recent study, published in the American Journal of Hematology, observed that iron-deficiency anemia (IDA) during pregnancy is associated with an increased risk of postpartum venous thromboembolism (VTE).
More than 40% of women are reported to have iron deficiency anemia during pregnancy. Gestational IDA confers high risks of pregnancy complications such as preterm birth, preeclampsia, maternal mortality, and stillbirth. Also, VTE, including pulmonary embolism (PE) and deep vein thrombosis (DVT) occurs more significantly during pregnancy with a peak during the postpartum period. The association between IDA and thrombotic events during pregnancy has not been studied.

Against the above background, Hao Ying, Tongji University School of Medicine, Shanghai, People's Republic of China, and colleagues aimed to study the association between IDA at admission for delivery and the postpartum VTE risk associated, as well as the potential pathway through thrombocytosis.
For this purpose, the researchers used a large institutional electronic medical records dataset to describe the rate of thrombocytosis in women at admission for delivery and the frequency of postpartum VTE. This dataset included all women delivering at Shanghai First Maternity and Infant Hospital (SFMIH), Tongji University School of Medicine from Jan. 1, 2019, to Dec. 31, 2021. Over 79,000 women who gave birth in Shanghai, China, were evaluated.
Key findings include:
A total of 107 women experienced postpartum VTE events.
Multivariate analysis showed that VTE was associated with anemia, low mean corpuscular volume, low ferritin levels, and thrombocytosis.
The adjusted odds ratio for VTE appeared to increase as hemoglobin levels decreased. This was independent of VTE prophylaxis, which was offered to women deemed at high risk after cesarean section.
These findings were controlled in women with baseline thrombotic disorders, blood disorders, or alternative sources of bleeding.

"We observed IDA during pregnancy was associated with increased risk of postpartum VTE," the authors wrote in their conclusion.
"Given the global burden of unrecognized and undertreated IDA during pregnancy, our findings emphasize the clinical implication of prompting identification and appropriate treatment of this common hematologic disorder."
Reference:
Liu X, Liu Y, Qu C, Mol B, Li W, Ying H. The association of iron-deficiency anemia, thrombocytosis at delivery and postpartum venous thromboembolism. Am J Hematol. 2022 Jul 9. doi: 10.1002/ajh.26657. Epub ahead of print. PMID: 35809246.