While the vast majority of these pregnancies (94 percent in 1997) are twins, the rates for triplets and other higher-order multiples are growing at an even faster rate. According to a paper published by Dr. Louis Keith, Susan Klock, Ph.D. and Dr. Sanjay Gandhi, "In little more than two decades, the subject of multiple pregnancy has evolved from an obstetric curiosity to an issue of international medical and social concern."

All About Twins
About two-thirds of twins are not identical. Commonly called fraternal twins, the correct scientific term for these twins is dizygotic. Dizygotic twins are the result of two separate eggs being ovulated and fertilized at the same time by two different sperm, thus giving these twins each a different genetic makeup.

Twins who share the same genetic makeup are commonly referred to as identical twins, though the correct scientific name for these twins is monozygotic. Identical twins are conceived when an egg, fertilized by one sperm, divides into two separate embryos. Identical twins not only usually look alike, they also are always of the same sex and blood type. While in the womb, they share the same placenta.

According to the National Center for Health Statistics, the number of twins born increased from more than 68,000 in 1980 to more than 104,000 in 1997.

While twinning rates have increased for all age groups, the increases were most dramatic among women 30 and over (the age group most likely to take advantage of ART). Twin birth rates increased by 41 percent for women in their 30s, by 63 percent for women 40 to 44 years old and by nearly 1,000 percent among women 45 to 49 years of age. Most of the women in this last age group used donor ovum (eggs donated by younger, fertile women). There were more twins born to women ages 45 to 49 in 1997 than during the entire decade of the 1980s.

Three or More?
While identical triplets – or even quadruplets! – are not unheard of, they are very rare. Most "higher order multiples" (triplets or higher) are the result of ART, though not always of in-vitro fertilization (IVF). According to Dr. Lisa Erickson, a reproductive endocrinologist in Minneapolis, superovulatory drugs coupled with intrauterine insemination (IUI) can also produce a high order multiple pregnancy.

In cases where a woman has many egg follicles, thus increasing her chances of multiple pregnancy, Dr. Erickson says that cancelling the cycle may be a smart option. "Mentioning the McCaugheys (the Iowa family with septuplets) has helped me cancel cycles without much protest," she says. Dr. Erickson notes that sometimes cancelling a cycle is clearly the best option, but at other times, things aren’t as clear-cut. "Sometimes you are looking at an informed risk."

In some cases, the couple may be willing to take a risk – for example, if the woman is older or if the couple has been in treatment for a long time. According to Drs. Keith, Klock and Gandhi, "The desire for twins and triplets increased with the age of the couple (‘Let's get it over with’) … and as the length of infertility increased, infertile couples became more receptive toward the concept of having a pregnancy with twins or triplets." The doctors noted that this receptivity did not extend to quadruplets or quintuplets.

Dr. Erickson’s clinic generally follows the SART (Society of Advanced Reproductive Technology) guidelines for IVF, which suggest transferring a maximum of two embryos in the case of a patient younger than 35 and a maximum of three embryos in a patient who is older than 35, but she says they do sometimes deviate from these guidelines. "There are no absolutes," she says. Dr. Erickson’s clinic is, however, strongly committed to reducing multiple pregnancies, and following the SART guidelines reduces the chance of this happening.

The National Center for Health Statistics reports that between 1980 and 1997, the number of live births in triplet and other higher order multiple deliveries "soared 404 percent. Singleton births, in contrast, rose 6 percent."

Multiple Complications
The risks of multiples need to be understood by couples undergoing ART. The most significant short-term risks to the multiples themselves include preterm delivery and low birthweight, according to Drs. Keith, Klock and Gandhi, while long-term risks can include growth restriction, neurologic deficits and cerebral palsy.

The risks to the mother include pre-eclampsia, postpartum hemorrhage and anemia. Women who are pregnant with more than one child are much more likely to spend part of their pregnancy on bed rest in hopes that it will prolong the pregnancy. While most women are able to have relatively normal pregnancies and near-term births with twins, as the number of fetuses increases, so does the risk. For example, the rate of preterm delivery was 10 percent for singletons, 54.9 for twins and 93.6 for higher order multiples.

Drs. Keith, Klock and Gandhi stress the importance of patient education, including education about multifetal reduction. Multifetal reduction occurs when a woman who is pregnant with more than three fetuses undergoes a procedure to abort one or more of the fetuses in hopes of increasing the remaining fetuses' chances of survival. Dr. Erickson says that the possibility of multifetal reduction is discussed with every patient at her clinic.

An Agonizing Choice
Erica Whittley* says that she and her husband, Dave, were thrilled to learn, after five years of infertility treatment, that she was pregnant at last. When they learned, very early on, that there might be more than one baby, they were not prepared for what followed.

"I was 42," Erica says. "We had just about given up on our chances of becoming pregnant. In fact, we were scheduled for an interview with an adoption agency."

Erica and Dave learned that Erica was carrying five fetuses. "It is very hard to make the decision to selectively reduce when you have fought so hard to get pregnant," Erica says. "But our doctor felt that I didn’t have a good chance of carrying all the babies for very long. We sought counseling, and we decided that we would reduce in order to increase the chances of having at least one healthy baby."

After the fetal reduction, Erica carried two babies, both girls, nearly to term, delivering at 38 weeks. Both babies weighed more than 5 pounds at birth. Erica had a difficult pregnancy, including bed rest and high blood pressure.

"It was the hardest decision we’ve ever made, but we’d make the decision to reduce if we had it to do over," Erica says. "I am convinced that had we not reduced, I could very well have lost them all."

Some doctors fear that if ART-induced multiple pregnancy rates continue to rise, insurance health plans will refuse to cover pregnancies conceived in procedures not covered by insurance (IVF is often not covered by health insurance). Others point to countries like Great Britain, which introduced guidelines in January forcing women younger than 40 who are undergoing IVF to have no more than two embryos transferred.

In the IVF that led to Erica Whittley’s pregnancy, six embryos were placed into her uterus. "In previous IVFs, I’d had three embryos transferred each time, and they didn’t take. This time, I had six embryos, and none of them really looked good. No one knows why it worked this time and not the other two."

"I think we were more willing to gamble because, frankly, we were desperate," says Erica. She now wishes that her clinic had followed the SART IVF guidelines (under SART guidelines, a maximum of three embryos would have been transferred). "I think the doctors who cared for us should have had policies in place to prevent high-order multiple pregnancies. I don’t think we should have ever had to make that decision."

*Names have been changed to protect the privacy of the individuals.

Want to see more?

• Two at Once: Pregnant With Twins
• You're Pregnant With Twins – Now Keep Those Babies in There!
• High Tech Babies: In-vitro Fertilization
• Our Experiences With Twins
• Talk about it!