[Determination of menarche and primary amenorrhea]

It was the aim to determine recalled ages at menarche and prevalence of primary amenorrhea in a random sample of 3743 women, aged 15-44 years, in a Danish county. It was a further object to examine agreement between results obtained by the recall and the status quo method. Response rate was 78%. The prevalence of primary amenorrhea (menarche after the 18th birthday) was 0.48%. In the calculations the reported menarcheal ages were treated as age-at-nearest-birthday, i.e. the usual 0.5 year mid-point correction was omitted. The resulting mean ages showed close agreement with Danish menarcheal ages, obtained by the status quo method, covering the same period of time. On the other hand, previously published recall data for this period, including the 0.5 year correction, were almost consistently 0.5 year higher. It is argued that the 0.5 year midpoint correction should be omitted in recalled whole-year data.