If <6 weeks postpartum is a high risk factor for VTE, why is it UKMEC 2 for Combined hormonal HC for women 3-6 weeks following childbirth and not breastfeeding and have no other risk for VTE? What are the “other risk factors for VTE”?

Use of combined hormonal contraception (CHC) by women following childbirth 

The UKMEC table (Section B) for CHC/ postpartum (in non-breastfeeding women) notes that:

VTE risk is elevated during pregnancy and the postpartum period; this risk is most pronounced in the first 3 weeks after delivery, and then declines rapidly to near baseline levels by 42 days postpartum. In the absence of other risk factors, it is acceptable to prescribe CHC after 3 week postpartum in non-breastfeeding women.

Use of CHC may pose an additional increased risk for VTE in the presence of other risk factors for VTE, such as immobility, transfusion at delivery, BMI ≥30 kg/m2, postpartum haemorrhage, immediately post-caesarean delivery, pre-eclampsia or smoking. See method section of UKMEC for clarification/ evidence.

View the UKMEC.