Subfertility, defined as at least one year of unprotected intercourse with the same partner without conception, affects ten to fifteen percent of couples in the western world. Depending on the duration of the subfertility, a female factor is the dominant cause of subfertility in around 50%, a male factor in 20-26% and the cause is unexplained in 25-30%. In most couples, subfertility is of multifactorial origin and should therefore be considered as a complex disease. Whereas genetic causes are difficult to modulate, environmental and lifestyle factors implicated in reproduction are potentially amendable to curative or preventive measures. Worldwide, an increasing number of couples are treated by assisted reproductive technology (ART) to achieve pregnancy. Currently, the chance of achieving a clinical pregnancy is around 28-31% per started in vitro fertilization (IVF) cycle with or without intracytoplasmic sperm injection (ICSI) in the Netherlands. The advantage of the introduction of IVF and ICSI treatment is that it gives access to and information about the direct environment of the gametes and early developing embryo. On the other hand, IVF and ICSI treatment is introducing an artifactual endocrinologic milieu which may affect the quality of the embryo. Whether concentrations of nutrients and enzymes change due to ovarian hyperstimulation is unclear, but it has already been demonstrated that different ovarian stimulation regimens increase the rates of embryo aneuploidy.

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E.A.P. Steegers (Eric) , N.S. Macklon (Nick)
Erasmus University Rotterdam
Erasmus MC: University Medical Center Rotterdam

Boxmeer, J. (2009, January 14). The homocysteine pathway in human subfertility. Retrieved from