Relationship between Anaemia, Coagulation Parameters During Pregnancy and Blood Loss in Childbirth: A Prospective Cohort Study in India

Background: Moderate (Haemoglobin (Hb) 7-9.9g/dl) and severe anaemia (Hb <7g/dl) during pregnancy increase the risk of postpartum haemorrhage (PPH). Objectives were to investigate the association between coagulation parameters and severity of anaemia during pregnancy and relate these to blood loss at childbirth. Methods: A prospective cohort study of 1342 pregnant women in the third trimester from 10 hospitals across India. Hb and coagulation parameters: fibrinogen, D-dimer, D-dimer/fibrinogen ratio, platelets, and INR were measured at baseline. Participants were followed-up to measure blood loss within two-hours after childbirth, and ‘high blood loss’ was measured for a threshold ≥500ml. Associations between coagulation parameters, anaemia and blood loss were examined. Findings: In women with severe anaemia during the third trimester, the D-dimer was 27% higher, mean fibrinogen 117mg/dl lower, D-dimer/fibrinogen ratio 69% higher, and INR 12% higher compared to women with no/mild anaemia. Mean platelets in severe anaemia was 37.8X109/L lower compared with women with moderate anaemia. Similar relationships with smaller effect sizes were identified for women with moderate anaemia compared with women with no/mild anaemia. Lower Hb at baseline significantly increased the odds of high blood loss at childbirth, and a stronger effect was moderated by an increase in D-dimer. Interpretation: Altered blood coagulation profile in pregnant women with severe anaemia may be a risk factor for PPH and requires further evaluation. Funding Statement: The study is funded by a Medical Research Council (GCRF) Career Development Award to Manisha Nair (Grant Ref: MR/P022030/1) and Nuffield Department of Population Health – Pumppriming award. Declaration of Interests: The authors declare that they have no competing interests. Ethics Approval Statement: The study was approved by the institutional review boards (IRB) of each coordinating Indian institution, namely: Srimanta Sankaradeva University of Health Sciences, Guwahati, Assam; Nazareth hospital, Shillong, Meghalaya; Emmanuel Hospital Association, New Delhi; Mahatma Gandhi Institute of Medical Sciences, Sevagram, Maharashtra; and the Institute of Medical Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh. It also received approval from the Government of India’s Health Ministry’s Screening Committee, the Indian Council of Medical Research, New Delhi and by the Oxford Tropical Research Ethics Committee (OxTREC), University of Oxford, UK. Written informed participant consent was taken from all participants.