Efforts to reduce the multiple birth rate are also sources of tension in the industry.

One cycle of in vitro fertilization costs about $12,000. Women who are not successful the first time often try again and again, which can push the cost of having a baby to more than $100,000. Because the technology is often not covered by insurance, doctors say they are constantly urged by patients to implant extra embryos.

One woman, a nurse who could afford only one try at in vitro, pressured Dr. Chiu to transfer eight embryos. “I said under one condition,” Dr. Chiu remembered. “I made her sign an agreement that she would do selective reduction.” That agreement, to remove some of the embryos if they lived, was very likely unenforceable. But in the end it worked out. Only one embryo survived, and the woman gave birth to a healthy child, he said.

Dr. Chiu said that a situation in which he would implant eight embryos would be a rarity, adding, “I don’t think any doctor would try to make a multiple pregnancy.”

Ms. Suleman now has 14 children born through in vitro fertilization. In the NBC interview, she identified the clinic where she received her treatment as the West Coast IVF Clinic in Beverly Hills, Calif., which Dr. Kamrava runs. Dr. Kamrava did not return telephone calls seeking comment.

Ms. Suleman said in the interview that she was aware of the risks of multiple births, but that she wanted to use all the embryos available to her.

The treatment involves removing eggs from a woman’s ovaries, combining them with sperm in a laboratory, and implanting the resulting embryos in the woman’s uterus. (In some cases the eggs come from a donor.) The number of embryos implanted is often a judgment call and can make a big difference in a pregnancy’s outcome.

Image Nadya Suleman, and her fertility specialist, Dr. Michael Kamrava, who is being investigated to determine whether accepted standards of medical practice were violated. Credit... Left, Paul Drinkwater/NBC; right, Nick Ut/Associated Press

“Every single decision we make about embryo transfers is a tough one, because we don’t have a crystal ball,” said Dr. Jeffrey M. Steinberg, who runs the Fertility Institutes, a group of fertility clinics based in Southern California.