Embryos screened to reduce the risk of twins

Japanese researchers say women undergoing fertility treatment may soon be able to have their embryos screened to reduce their chances of giving birth to twins.

Researchers have been examining ways of developing the embryo for longer in the laboratory until the blastocyst stage before transferring it to the womb to maximise the chance of implantation.

Scientists at the Mio Fertility Clinic in Yonago, Japan used special "time-lapse" computer software to observe minute by minute what was happening to single IVF embryos as they grew in the lab.

By using a high magnification digital video camera were able to film embryos growing from just four cells until they were a ball of cells five days old.

They saw that after less than 12 hours in a culture dish, two of the embryos repeatedly collapsed upon themselves and then began swelling again and the images revealed the cells were re-arranged and formed two dark patches which split the embryo into two, forming identical twins.

The researchers say the breakthrough will allow doctors to spot early signs of embryos likely to divide into two, forming identical twins in the womb.

Multiple pregnancy can lead to babies being born prematurely and with a greater chance of having cerebral palsy and heart and lung problems and women carrying twins are at a greater risk of miscarrying and developing dangerously high blood pressure.

Currently 40% of IVF babies are twins which usually occurs because more than one embryo is implanted into the woman.

Embryos created at fertility clinics are up to seven times more likely to split into two and the researchers say the process of IVF encourages embryos to split into identical twins.

The research was presented at a fertility conference in Lyon, France.