During conventional IVF, unfertilized eggs and tens of thousands of sperm are mixed in a Petri dish and placed in a mechanical ventilator for up to five days, to allow fertilization and embryo development.
With the new technology, eggs and sperm are placed in a plastic egg-shaped capsule that is inserted into the woman’s vagina.
After three to five days, the device is removed, the capsule opened and the healthiest-looking embryos transferred to her uterus.
In a small study involving 10 women treated at the Toronto Centre for Advanced Reproductive Technologies (TCART), four became pregnant after using the “natural incubator,” known as INVOcell.
The centre says the device may appeal to women “who desire close connection to her own embryos” for personal or religious beliefs and may help alleviate “separation anxiety” by allowing them to carry their early embryos in their bodies for five days.
The idea was dreamed up more than two decades ago, partly as a way to allow “conception” after assisted-baby making to take place inside — not outside — the body.
The Toronto study, which has yet to be published, involved 10 young, healthy women. They were given fertility drugs to stimulate their ovaries to produce multiple eggs.
Eggs from the same patient were divided into two groups: half went into the routine IVF incubator, the other half into the INVOcell device.
“We wanted to compare apples with apples in terms of what was happening,” said Dr. Robert Casper, TCART’s medical director.
The embryos were removed on the third day. Only embryos from the INVOcell device were transferred to the women “to see if we could get pregnancies,” he added.
“The INVOcell device wasn’t quite as good as the incubator — we had one or two cases of failed fertilization. But we also had one or two cases of failed fertilization in the incubator, too.”
Since then, the team has learned from other researchers that rinsing the device with oil “seems to make a huge difference in terms of embryo development,” Dr. Casper said, perhaps by helping offset any toxicity from the plastic.
The Toronto group is now growing embryos for five days, instead of three, and injecting sperm directly into the eggs before placing them in the device.
With INVOcell, “The advantages are the patient has her embryos with her the whole time, and we’re not constantly looking at them, which some people think is a problem,” Dr. Casper said.
With a mechanical incubator, the temperature, humidity and pH levels change every time the incubator door is opened, “and that seems to add a little bit of stress to them.” By contrast, the conditions inside the woman’s body would be more constant.
The INVOcell devices also more closely mimic what happens naturally. Instead of sitting in a static lab dish, the early embryos “seem to roll around a little bit in this device,” the way they would normally in the Fallopian tubes.
The INVOcell system would add about $500 to the expense of IVF, which typically costs about $12,000 a cycle.
Dr. Roger Pierson, a University of Saskatchewan-based fertility scientist, said there are no known risks with the procedure, which may appeal to women who have a religious conviction conception should occur as naturally as possible.
“This whole business is about helping people conceive within the limits of their own personal belief system,” he said.