Pressor effects of thyrotrophin releasing hormone during thyroid function testing.

similar reasons we thought that it would not be helpful to go back to our records of the women aged 50 to establish how many of these had delayed their first live birth until the age of 35 and over, as they formed such a different group from our current 35 year olds. The difficulty in classifying voluntarily childless women has been considered elsewhere.8 A woman's perception of her childless state may well alter during her reproductive life. She may be "infertile" during one liaison but "childless by choice" in another; she may leave conception to chance without pursuing the option of treatment ; or she may declare her childlessness, in retrospect, to be voluntary in order to avoid the stigma of infertility. We were intrigued by the group of childless women who were not using prescribed contraception but had never sought help for infertility. Possible reasons include (a) no established sexual relationship (including non-consummation of marriage); (b) voluntarily childlessness, using non-prescription methods successfully; (c) a partner who had already had a vasectomy in a previous relationship; (d) sexual problems, including impotence ofa partner; (e) too ashamed or embarrassed to seek help for infertility. It was noticeable that this group contained many patients who did not often consult their doctors. The presence of this unclassified group means that our estimates of infertility and voluntary childlessness are necessarily imprecise; even if we had more information women in some of the above categories would be difficult to classify. Our method ofdividing this group (in the same proportions as those for whom the reason for childlessness was known) is open to question, but it produced figures for the two age groups which could conveniently be compared. A recent paper concluded that infertility is becoming more prevalent.'2 Despite the large increase which we found in the proportion of women aged 35 who were childless compared with those aged 50, and the increase in the number of women requesting specialist consultations for infertility, we found no evidence of an increase in involuntary childlessness-that is, due to infertility. Our range of 3 3% to 4 5% is much lower than the 8-10% predicted by previous statistical projections. The number of women who chose to remain childless greatly increased during the study period; we estimate that they accounted for one in nine ofall 35 year olds.-This figure has not been measured in any previous British report, though …