Haemostatic changes in the puerperium '6 weeks postpartum' (HIP Study) - implication for maternal thromboembolism.

OBJECTIVE: We aim to measure the thrombotic changes during the postnatal period up to 6 weeks after delivery and assess the extent of the risk period.
DESIGN: Prospective observational study.
SETTING: Queen Elizabeth II, an acute District General Hospital, Hertfordshire. POPULATION: Women booked at the antenatal clinic and prepared to deliver at the hospital.
METHODS: We assessed the haemoglobin, platelet count and function, fibrinogen, prothrombin time, activated partial thromboplastin time, protein C, S and antithrombin level and as well as rotational thromboelastometry (ROTEM) from predelivery till 6 weeks postpartum.
RESULTS: A total 50 women were recruited of which four dropped out. Results compared against the finding at 6 weeks after delivery. Platelet was significantly elevated on day 19 compared to day 42 (P < 0.001). Fibrinogen was elevated from predelivery till day 15 after delivery (P < 0.01). Prothrombin time (PT) was low till day 15 (P < 0.05) and activated partial thromboplastin time (APTT) was significantly lower till day 3 after delivery (P < 0.001). ROTEM revealed low clotting time (CT) at predelivery and continued to be low till day 7. Clot formation time (CFT) significantly low till day 25 (P < 0.05). Maximum clot firmness, alpha angle and amplitude at 20 minutes were raised till day 19 (P < 0.001, P < 0.01 and P < 0.001 respectively). While, comparing vaginal delivery against caesarean section there were nonsignificant increase in thrombotic parameters in caesarean section.
CONCLUSION: Coagulation screens as well as thomboelastometry suggest a persistent hypercoagulation during the first 3 weeks after delivery.