The influence of obesity on coagulation in healthy term pregnancy as assessed by rotational thromboelastometry

Rotational thromboelastometry (ROTEM^® ) is a point-of-care coagulation test which has been used to demonstrate hypercoagulability in pregnant populations and obese populations.

The aim of this study was to assess the combined effect of pregnancy and obesity on coagulation using ROTEM^® in healthy pregnant women of varying body mass indices (BMIs) presenting for elective caesarean delivery.

Ethics approval was granted for recruitment of women presenting for elective caesarean delivery. Women with any condition affecting coagulation were excluded. The ROTEM^® parameters of extrinsically activated thromboelastometric test / fibrin polymerisation test (EXTEM/FIBTEM) amplitude at five minutes (A5), coagulation time (CT), maximum clot firmness (MCF) and clot formation time (CFT) were compared between three different groups: normal weight, overweight and obese women.

One hundred and eighty-five women presenting for elective caesarean delivery met inclusion criteria and were divided into three groups; normal weight (BMI < 25 kg/m² , n = 86), overweight (BMI 25-29.9 kg/m² , n = 54) and obese (BMI ≥ 30 kg/m² , n = 45). They had a mean (SD) age of 32.7 ± 5.0 years and the median (interquartile range) BMI of 21.9 kg/m² (20.5-23.0), 27.0 kg/m² (26.0-28.5), 36.0 kg/m² (32.2-41.8) for the normal weight, overweight and obese groups respectively. Forty-one (22.2%) women were nulliparous. Across the three groups for FIBTEM A5 (P = 0.018), FIBTEM MCF (P = 0.032), FIBTEM CFT (P = 0.047) and EXTEM MCF (P = 0.015) there was evidence of increasing coagulability with increasing BMI. However, following Bonferroni correction, this was no longer significant.

There is no association between BMI and ROTEM^® parameters in pregnant women presenting for elective caesarean delivery at term.