More evidence that hormone testing for women's fertility does not work.Women seeking to defer motherhood are often encouraged to check their fertility.Though fecundity is tied to age, the effect of time's passage varies.Some 35-year-olds find they cannot get pregnant.Others manage at the first attempt.The main causes of fertility's reduction with advancing years are declines in the number and quality of the eggs in a woman's ovaries.Unlike men, who manufacture sperm throughout their post-pubertal lives, albeit in ever-decreasing quantities, all of a woman's potential eggs develop while she is still a fetus.A newborn girl has over 1m of them.By puberty, she is left with about 400,000.When the menopause arrives, that has been whittled down below 1,000, which are likely to be duds.But fertility tests currently on offer neither count the number of eggs remaining nor assess their quality.Rather, they rely on an indirect approach - sampling what are hoped to be relevant hormones.Hormone tests do have some value in estimating the timing of menopause and the success of harvesting eggs for in vitro fertilisation.But forecasting pregnancy?The evidence suggests that they can't.One test-sceptic is Anne Steiner of the Duke Fertility Centre, in North Carolina.She suspects hormone tests do indicate how many eggs are left to a woman, but that this is not what matters - rather, it is the eggs' quality which is crucial.
