. 2019 Dec 26;4(2):183–192. doi: 10.1002/rth2.12290

Table 1.

aOR and IRR reported for selected maternal, pregnancy, and delivery characteristics in the listed studies

Maternal characteristics
Risk factor	Selected aOR/IRR (95% CI)
Age > 35 y	1.3 (1.0‐1.7)16
Parity ≥ 3	2.4 (1.8‐3.1)16
BMI ≥ 25kg/m²	1.8 (1.3‐2.4)^a ^, 17
BMI ≥ 25kg/m² + antepartum immobilization	62.3 (11.5‐337.6)^a ^, 17
Smoker^b	2.1 (1.3‐3.4)^a ^, 17
ART (singleton)	4.3 (2.0‐9.4)^a ^, 17
Varicose veins^d	2.21 (1.55‐4.76)^a ^, 23
Inherited thrombophilia	Variable (0.7‐34.4)26
Prior VTE	24.8 (17.1‐36.0)18
Antiphospholipid syndrome	15.8 (10.9‐22.8)18
Sickle cell disease	6.7 (4.4‐10.1)18
Preexisting diabetes^d	3.54 (1.13‐11.0)23

Pregnancy Characteristics
Risk factor	Selected aOR (95% CI)
IUGR	3.8 (1.4‐10.2)^c ^, 17
Preeclampsia	3.1 (1.8‐5.3)^c ^, 17
Twins	2.6 (1.1‐6.2)^a ^, 17

Delivery characteristics
Risk factor	Sample aOR/IRR (95% CI)
Preterm delivery^d	2.28 (1.66‐3.14)^c ^, 23
Emergency CS	2.7 (1.8‐4.1)^c ^, 17
Stillbirth^d	4.07 (1.73‐9.56)^c ^, 23
Infection (CS)	6.2 (2.4‐16.2)^c ^, 17
PPH ≥ 1000 mL	4.1 (2.3‐7.3)^c ^, 17
Infection (VD)	20.2 (6.4‐63.5)^c ^, 17

The reported strength of these characteristics is highly variable between studies: the intention of this table is to raise awareness of the need to consider individualized risk assessment at these times in the pregnancy journey rather than to comprehensively review all reported risk factors.

Abbreviations: aOR, adjusted odds ratio; ART, assisted reproductive technology; BMI, body mass index; CI, confidence interval; CS, cesarean section; FHx, family history of VTE; IRR, incidence rate ratio; IUGR, intrauterine growth restriction; PPH, postpartum haemorrhage; VD, vaginal delivery.

As a predictor of antenatal VTE events.

10‐30 cigarettes per day.

As a predictor of postnatal VTE events.

Denotes IRR rather than aOR.