Risk scores, prevention, and treatment of maternal venous thromboembolism

Table 1 Pregnancy-related venous thromboembolism risk factors

Risk factor	Cases	Proportion (%)
Pre-existing risk factors
History of previous VTE (except for surgery-related VTE history)	0	0
Surgery-related VTE history	0	0
Known high-risk thrombophilia	0	0
Medical complications, such as cancer, cardiopulmonary disease, systemic lupus erythematosus, inflammatory polyarthrosis, inflammatory bowel disease, nephrotic syndrome, type 1 diabetic nephropathy, sickle cell disease	48	0.62
Family history of VTE with unknown cause or oestrogen in first-degree relatives	1	0.01
Known low-risk thrombophilia (no history of VTE)	0	0
Age (> 35 yr old)	1472	18.97
Obesity (BMI > 30)	3978	51.26
Parity ≥ 3	31	0.40
Varicose veins	23	0.29
Smoking	42	0.54
Obstetric risk factors
Preeclampsia	716	9.23
Assisted reproductive technology	197	2.53
Multiple pregnancies	186	2.40
Caesarean section	3680	47.42
Extended labour (> 24 h)	826	10.65
Postpartum haemorrhage (bleeding > 1000 mL or blood transfusion)	156	2.0
Premature delivery (< 37 wk)	342	4.41
New or transient risk factors
Pregnancy or puerperal surgery (except for perineal repair immediately after delivery)	56	0.72
Hyperemesis gravidarum	68	0.87
Ovarian hyperstimulation syndrome	31	0.40
Infection	71	0.92
Hospitalization or bed rest, immobilization ≥ 3 d	103	1.32

VTE: Venous thromboembolism; BMI: Body mass index.