Last reviewed 01/2018

In the Women's Health Initiative study there was a relative risk 1.41 at 5.2 years of the development of a stroke (comparing oestrogen plus progestogen arm vs. placebo group) (1) - this meant an increased absolute risk of 8 per 10,000 women per year.

NICE state with respect risk of stroke with HRT (2):

Explain to women that taking oral (but not transdermal) oestrogen is associated with a small increase in the risk of stroke

  • the baseline population risk of stroke in women aged under 60 years is very low

  • Table: Absolute rates of stroke for different types of HRT compared with no HRT (or placebo), different durations of HRT use and time since stopping HRT for menopausal women
    • difference in stroke incidence per 1000 menopausal women over 7.5 years (95% confifidence interval) (baseline population risk in the UK over 7.5 years: 11.3 per 1000
    Current HRT users Treatment duration <5 years Treatment duration 5-10 years >5 years since stopping treatment
Women on oestrogen alone RCT estimate 0 (-5 to 10) No available data No available data 1 more (-4 to 9)
Women on oestrogen alone Observational estimate 3 more (-1 to 8) No available data No available data No available data
Women on oestrogen + progestogen RCT estimate 6 more (-2 to 21) No available data No available data 4 more (-1 to 13)
Women on oestrogen + progestogen Observational estimate 4 more (1 to 7) No available data No available data No available data


  1. Writing Group for the Women's Health Initiative Investigators. Risks and benefits of estrogen plus progestin in healthy postmenopausal women. Principal results for the Women's Health Initiative Randomized controlled trial. JAMA 2002; 288:321-333.

  2. NICE (November 2015). Menopause: diagnosis and management