Antenatal screening for Down's syndrome: where are we and where next?

Sir-In his viewpoint, Hugh TunstallPedoe (May 9, p 1425)’ reinvents a paradox about menopause and risk of coronary heart disease (CHD) that has been known for 30 years.’ He concludes that menopause is not a risk factor for CHD, on the basis of the observation that a semilogarithmic plot of CHD mortality rates by age does not show an increased acceleration in women after the age of . 50. We believe that this approach is not justified for examination of the effect of menopause. First, an increased acceleration of , CHD mortality rates at or after the age of menopause implies that the relative risk associated with menopause continuously increases with age, which is not seen for any CHD risk factor, including hypertension and smoking. Second, since the acceleration of CHD mortality rates declines with age in men, an increased acceleration in women is unlikely, even when menopause raises the risk. We have examined the effect of menopause on CHD in a simulation model with more realistic assumptions. We used mortality rates of UK men,’ the Framingham risk function,’ and estimates of relative risks at young ages from the MRFIT Study,4 to construct a graph of CHD motality rates in men in the first decile of the Framingham risk score to represent women premenopausal until the end of life (figure). On the basis of estimates of the effect of age at menopause,5 we assumed menopause to enhance CHD mortality by 20, 60, and 100% at ages 50-54, 55-59, and ’