Scientists have no discovered a way to decipher whether women will need one or two embryos to be transferred during in vitro fertilization. This will decrease the chances of having twins, which is a common occurrence.

The way IVF works, is a women’s eggs are fertilized by sperm in a test tube which creates an embryo. The embryo is then placed back inside the womb. When too many embryos are transferred at a time it can work.

Researchers in Sweden have claimed that they have found the issue has been solved. Their model is applied to fertility clinics which can detect whether women will need one or two embryos transferred in order to become pregnant. This reduces the twin rate level to just under 2% for the general population.

Single embryo transfer will reduce multiple pregnancies the most, and in 2007, which was the year for which most data was available, 69.9% of transfers were single embryos.

Dr. Jan Holte, of Uppsala Science Park states: “Until now, evidence-based strategies have been lacking for guidance on when to perform single embryo transfers in order to achieve the best possible balance between maintain a high level of birth rates, but reducing twin implantation rates”.

Dr. Holte states that women who are pregnant with twins through IVF are more likely to experience health problems such as hypertension, pre-eclampsia, and gestational diabetes.

He presented the model at the annual meeting of the European Society for Human Reproduction and Embryology in Stockholm.