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Better lab techniques can reduce risk of multiple births, says Dr. Pradeep Warikoo. (Glenn Hartong photo) | ZOOM |

If Drs. Glen Hofmann and Pradeep Warikoo have anything to say about it, the rising numbers of triplets, quadruplets and quintuplets born to people going through fertility treatments will soon be a historic oddity.

That's because a still-new technique of growing embryos to the blastocyst stage before placing them in the mother's womb has dramatically reduced multiple births at some fertility centers.

In just one year of increased use of blastocysts, the Bethesda Center for Reproductive Health and Fertility reported its overall multiple birth rate (for women under 37) dropped from 42 percent in 1998 to 12.9 percent in 1999. Multiple births involving triplets or more fell from 4.6 percent to 0.9 percent.

Such statistics are good news to most would-be parents who prefer to avoid multiple births.

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Reducing multiple births

"I'm a nurse in the NICU (neonatal intensive care unit) at Children's Hospital. I've seen the things that can happen with multiples," said Kim Kunkel, who gave birth five weeks ago to her son, Ryan, after receiving a blastocyst transfer.

"We were really hoping for only one. When we discussed it, we thought twins would be OK. But we were interested in anything that would cut down on (the risk of) multiples," Mrs. Kunkel said.

Although news organizations lavish attention on couples who become parents five, six and seven times at once, many fertility specialists consider any pregnancy involving more than twins to be a failure of science that puts the mother and children at risk.

In 1997, America was amazed when the McCaughey septuplets were born in Iowa. Then in December 1998, the Chukwu octuplets were born in Texas. This year in New Jersey, Ivette Zapata-Smalls was making headlines with another set of septuplets, until she lost them all.

"Situations like those are an embarrassment to the profession," Dr. Hofmann said. "Trying to avoid multiple births is a standard discussion with most of our patients."

Without close medical supervision, a multiple pregnancy can kill the mother. More commonly, however, the babies struggle to survive. Every set of quintuplets or more, even the vast majority of triplets - requires intensive care at birth. Deaths are common. Survivors with permanent health problems are even more common, Dr. Hofmann said.

When considering fertility treatment, couples have always faced a double-edged risk. On one hand, the high-cost procedures can easily fail to result in a pregnancy. On the other hand, they can work so well that multiple pregnancies result.

In addition, the lowest-cost options - such as taking fertility drugs but not going through in-vitro fertilization - present the highest risk of large numbers of babies.

Now, however, better lab techniques can reduce the risks, Dr. Warikoo said.

The process starts with a woman taking fertility drugs to stimulate egg production. A single drug-enhanced menstrual cycle can produce 10 or more eggs.

For in-vitro fertilization, specialists retrieve these eggs, fertilize them with sperm, then try to grow them in the lab. In just three days, the fertilized egg can grow to an eight-cell embryo.

Typically, fertility specialists implant two to five eight-cell embryos in hopes of achieving a single pregnancy. Most women get three or four at a time, Dr. Warikoo said, but the number varies depending on the age of the woman, the number and condition of the embryos, previous failed attempts and other factors.

Now instead of implanting eight-cell embryos, some fertility labs are consistently growing embryos as long as six days, allowing them to reach the blastocyst stage.

With hundreds of cells doubling every 16 hours, blastocysts have already overcome genetic and chemical problems that prevent many eight-cell embryos from ever growing further. Simply by surviving this long, a blastocyst is more likely than an eight-cell embryo to result in a successful pregnancy.

Implanting one or two blastocysts resulted in about a 70 percent pregnancy rate, according to a study published in 1998 by geneticist David Gardner and fertility specialist Dr. William Schoolcraft of the Colorado Center for Reproductive Medicine.

That's about the same success rate as implanting three or four eight-cell embryos - only without the risk of high numbers of multiple births.

"We're at the point right now where our patients are routinely offered a blastocyst transfer," Dr. Hofmann said.

The biggest limitation to the concept has been that growing a blastocyst isn't easy.

It took years for researchers to learn that the nutrient needs of human embryos quickly become more selective as they grow. That means the same culture medium that helps feed an eight-cell embryo cannot support a blastocyst, Dr. Warikoo said.

Once the Bethesda labs started using the two-stage process needed to grow a blastocyst, it still didn't offer the service routinely until the lab could consistently produce at least two blastocysts for implantation.

For Mrs. Kunkel, the lab retrieved and fertilized 14 eggs. Three survived to blastocyst stage and were implanted. One survived to become Ryan.

Most commonly, fertility labs implant only two blastocysts at a time. In most cases, only one survives. Of nearly 100 births after a blastocyst transfer, three were multiples. One couple that wanted three blastocysts implanted got triplets; the other two sets were twins.

"In about a year or so, the pressure will be for all of us to do blastocysts," Dr. Hofmann said. "After that, it won't be too long before the numbers of triplets, quads and quints start fading away."