Erasmus MC University Medical Center Rotterdam, Department of Public Health, Room 2061, Dr Molewaterplein 50, 3015 GE Rotterdam, The Netherlands. e-mail: j.vandersteeg{at}erasmusmc.nl
Dear Sir,
We read with interest the study of Gnoth et al. (2003) that reported fecundity in a cohort of 346 couples that stopped contraception with the aim to conceive. The study shows that 80% of the couples conceived within 6 months. From the remaining 20%, almost 60% conceived within the next 6 months. Although the data obtained by these authors are unique and of high quality, we firmly disagree with their interpretation when the authors propose a new threshold for a baseline fertility work-up after 6 months of unprotected intercourse.
First, there exists no test that can distinguish between normal fertile and subfertile couples. Although prediction models using a baseline fertility work-up can discriminate between couples with a high chance of treatment-independent conception and couples with a low chance, there is a huge overlap in test results between these couples (Eimers et al., 1994; Wichmann et al., 1994
; Collins et al., 1995
; Snick et al., 1997
). The proposal of a first assessment at 6 months can only be made seriously if they show that the proposed tests can discriminate those who will conceive without treatment and those who will need treatment after a longer period.
Secondly, the treatment-independent conception rate of those couples that had not conceived after 6 months was almost 60%. This rate is superior to any other treatment strategy that is currently offered to subfertile couples. Any treatment with a success rate of more than 50% without any side effects and at no costs would be embraced as a breakthrough in fertility care. In their proposal, the authors suggest leaving such a strategy. Their proposal will harm couples with complications and multiple pregnancies as the result of overtreatment, at unnecessary costs.
References
Collins JA, Burrows EA and Wilan AR (1995) The prognosis for live birth among untreated infertile couples. Fertil Steril 64,2228.[Medline]
Eimers JM, te Velde ER, Gerritse R, Vogelzang ET, Looman CW and Habbema JD (1994) The prediction of the chance to conceive in subfertile couples. Fertil Steril 61,4452.[Medline]
Gnoth C, Godehardt D, Godehardt E, Frank-Herrmann P and Freundl G (2003) Time to pregnancy: results of the German prospective study and impact on the management of infertility. Hum Reprod 18,19591966.
Snick HK, Snick TS, Evers JL and Collins JA (1997) The spontaneous pregnancy prognosis in untreated subfertile couples: the Walcheren primary care study. Hum Reprod 12,15821588.[Abstract]
Wichmann L, Isola J and Tuohimaa P (1994) Prognostic variables in predicting pregnancy. A prospective follow up study of 907 couples with an infertility problem. Hum Reprod 9,11021108.[Abstract]