During in vitro fertilization, uterine contractions can reduce a woman’s chance of becoming pregnant. A new study published in the journal Fertility and Sterility, however, finds the opposite is true during artificial insemination.
Lead researcher Manuel Fernández and his team, from the Valencia Infertility Institute in Spain, found that the more uterine contractions women have per minute during artificial insemination, the more likely it is that the procedure will be successful.
Artificial insemination, also referred to as intrauterine insemination (IUI), involves directly inserting sperm into a woman’s uterus during ovulation. The aim of this procedure is to boost the chance of fertilization by increasing the number of sperm that reach the fallopian tubes.
IUI is a much cheaper and simpler form of fertility treatment than in vitro fertilization (IVF), which is why it is the most widely used procedure. But the research team note that the success rate of IUI is lower than more complex fertility treatment and, as such, the procedure has lagged in terms of development in recent years.
In their study, Fernández and his team set out to find factors that may improve the success of IUI.
Success of IUI influenced by uterine contractions, follicular rupture
The researchers analyzed data of 610 women who underwent IUI with either a partner’s sperm or a donor’s sperm between 2005 and 2010.
Results of the analysis revealed that the number of uterine contractions a woman has each minute during artificial insemination is positively linked to the number of live births. “When the number of contractions is high, the rates of pregnancy and live births are also notably elevated,” explains Fernández.
The team also found that the timing of insemination appeared to be an important influence on its success, with significant improvement seen when the procedure was conducted the same day as follicular rupture – the release of oocytes, or eggs.
Other factors that appear to affect the success of IUI – independent of live births – include whether a woman is inseminated with sperm from a partner or donor, maternal age and the number of follicles.
Taking all these factors into account, the team says IUI could offer a 15-20% success rate per cycle with a partner’s sperm and a 25% success rate per cycle with a donor’s sperm.
Commenting on their findings, Fernández says:”If we manage to improve artificial insemination success rates using this and other studies, we would be contributing to an important advance, given that this is currently the most accessible and widely used treatment.”