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The relative contribution of IVF to the total ongoing pregnancy rate in a subfertile cohort.

BACKGROUND
Although in vitro fertilization (IVF) was introduced more than 30 years ago, its exact role in the spectrum of fertility treatments has never been studied in an unselected population. The aim of this study was to visualize the contribution of IVF to the ongoing pregnancy rates in a cohort of newly referred subfertile couples.


MATERIALS
All new subfertile couples (n = 1391) that were referred to our fertility clinic by their general practitioner between January 2002 and December 2006 were included. Fertility care was provided according to the national Dutch fertility guidelines. Data on diagnosis, treatment, mode of conception and pregnancy outcome were documented. If follow-up data were missing, couples were contacted. Cumulative pregnancy curves were constructed for the whole cohort and per diagnostic group.


RESULTS
As per December 2008 the overall ongoing pregnancy rate was 72.0% (n = 1001). Almost half of the pregnancies were conceived spontaneously (45.6%), 19.2% after ovulation induction (OI), 14.0% after intrauterine insemination (IUI) and 21.2% after IVF. A quarter (n = 349) of couples received IVF treatment, which was successful in 60% of cases. IVF had the largest contribution to ongoing pregnancies in patients with 'tubal factor', 'endometriosis' and 'male factor' (45, 45 and 37%, respectively) while in couples with 'unexplained subfertility' and 'ovulation disorders' the contribution to ongoing pregnancies of IVF was limited (13 and 4.5%, respectively).


CONCLUSIONS
In a cohort of subfertile couples, most pregnancies were conceived spontaneously. The contribution of IVF to ongoing pregnancy rates was comparable to those of OI and IUI. Compared with the pre-IVF era, couples with 'endometriosis', 'tubal factor' and 'male subfertility' have benefited most from its introduction.