Table 2

 Venous thromboembolism and pulmonary embolism events in pregnant women after in vitro fertilisation (IVF) and women with natural pregnancies matched on age and calendar period of delivery. Values are numbers (percentages) of women unless stated otherwise

Events in relation to pregnancyIVF pregnancies (n=23 498)Natural pregnancies (n=116 960)Proportional hazard regression (95% CI)
Venous thromboembolism:
 Prepregnancy71 (0.30)415 (0.35)0.85 (0.66 to 1.10)
 Pregnancy and delivery99 (0.42)291 (0.25)1.77 (1.41 to 2.23)
 Days 43-365 postpartum24 (0.10)95 (0.08)1.29 (0.82 to 2.02)
Pulmonary embolism:
 Prepregnancy21 (0.09)103 (0.09)1.04 (0.65 to 1.66)
 Pregnancy and delivery19 (0.08)70 (0.06)1.42 (0.86 to 2.36)
 Days 43-365 days postpartum3 (0.01)26 (0.02)0.60 (0.18 to 1.98)