A common definition of sub- and infertility is very important for the appropriate management of infertility. Subfertility generally describes any form of reduced fertility with prolonged time of unwanted non-conception. Infertility may be used synonymously with sterility with only sporadically occurring spontaneous pregnancies. The major factor affecting the individual spontaneous pregnancy prospect is the time of unwanted non-conception which determines the grading of subfertility. Most of the pregnancies occur in the first six cycles with intercourse in the fertile phase (80%). After that, serious subfertility must be assumed in every second couple (10%) although--after 12 unsuccessful cycles--untreated live birth rates among them will reach nearly 55% in the next 36 months. Thereafter (48 months), approximately 5% of the couples are definitive infertile with a nearly zero chance of becoming spontaneously pregnant in the future. With age, cumulative probabilities of conception decline because heterogeneity in fecundity increases due to a higher proportion of infertile couples. In truly fertile couples cumulative probabilities of conception are probably age independent. Under appropriate circumstances a basic infertility work-up after six unsuccessful cycles with fertility-focused intercourse will identify couples with significant infertility problems to avoid both infertility under- and over-treatment, regardless of age: Couples with a reasonably good prognosis (e.g. unexplained infertility) may be encouraged to wait because even with treatment they do not have a better chance of conceiving. The others may benefit from an early resort to assisted reproduction treatment.

AMH is a predictor of ovarian response and suitable for screening. Levels < or =1.26 ng/ml are highly predictive of reduced ovarian reserve and should be confirmed by a second line antral follicle count. Measurement of AMH supports clinical decisions, but alone it is not a suitable predictor of IVF success.

Most couples with infertility problems can be treated successfully if they continue treatment. Thereby ART can reach natural fertility rates. Even with the restrictions in place as a result of the German Embryo Protection Law, CLBR reach internationally comparable levels.

Neither the source of spermatozoa nor the etiology of severe male infertility has relevant impact on the results of ICSI cycles as long as fresh motile, morphologically normal spermatozoa are used. Therefore, in case of cryptozoospermia, we recommend to preferentially use ejaculated spermatozoa to prevent those men from an unnecessary testicular biopsy avoiding risks and costs implied.

The primary intention for the choice of fertilization modality between IVF and ICSI is the prevention of a relative or total fertilization failure. Such treatment failure is best prevented through ICSI, which results in slightly higher clinical pregnancy rates per started cycle. After embryo transfer, there are no differences in the success rates of IVF and ICSI. The supposed cumulative live-birth rates are useful as a basis for counselling subfertile couples to help reduce the high discontinuation rate, which is still the main reason for inefficacy in ART. Following an unsuccessful first treatment cycle, the prognosis remains positive, but until success is achieved, more treatment cycles are necessary.