thesis
The homocysteine pathway in human subfertility
- Publication date
- 14 January 2009
- Publisher
- 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.