Their 41-year-old mother, Maricella Duran, thought she'd done everything she could to avoid having more children. She said she knew she couldn't support them.

A previous pregnancy had been difficult for Duran, and she felt that she was too old to safely get pregnant again.

That's why, Duran said, she asked her doctor, Fred Schnepper, to take out her uterus. He explained to her, she said, that it would be better to do a tubal ligation.

A tubal ligation is a procedure that clips the fallopian tubes to prevent fertilization.

Duran agreed to it, but there was a problem. Her attorney, Gene Iredale explained, "He failed to place the clip on the tube."

Iredale said Schnepper instead clipped a different structure inside Duran's body. She became pregnant with the twin boys 17 months after the procedure.

It was a complicated pregnancy, Duran said. She had to be hospitalized, and her babies were born 2 1/2 months premature.

The medical expenses were huge, Iredale said, more than $534,000. He said the doctor's age was a factor.

"The doctor was over 70 at the time of the surgery, and the doctor suffered from a tremor," Iredale said.

A jury awarded the Duran's family nearly $1 million for medical expenses and the cost of raising the twins.

Schnepper declined to be interviewed by 10News, but his attorney, Nancy Vaughn, sent this statement:

"Fred Scnepper is one of San Diego's Premiere Ob/Gyns. Not only has he has performed more tubal ligations than 90 percent of the ob/gyn's in San Diego County, he has taught numerous physicians in this country and in Mexico how to do them. Tubal ligations have a known failure rate; they can and do fail even in the hands of the most skilled physicians. In this case, there is still a dispute as to the cause of Ms. Duran's tubal ligation failure. Ms. Duran's expert witness at one time testified that her tubes had been properly ligated. He changed his testimony on that issue one month before trial started. At this time Dr. Schnepper is considering an appeal of the verdict rendered against him."

Schnepper is now 74 years old and is still practicing. Unlike commercial airline pilots, who must retire at age 65, there is no upper age limit for doctors. There is no oversight, screening, or assessment of older doctors, unless a problem is reported.

Dr. Bill Norcross is a clinical professor at the University of California, San Diego Medical School. He has no knowledge of Schnepper's case. Norcross also runs a program that assesses doctors who are going through medical board investigations. The average age of the doctors he sees in the program is 64 or 65. He believes there should be some oversight of aging doctors.

"At a given age, I do personally think doctors should be observed doing what they're doing and undergo some sort of assessment," he said.

He's not sure what age that should be, but guessed that 65 may be appropriate.

In the U.S. there are more than 187,000 doctors who are age 65 or older. In California, there are more than 26,000.

Norcross said there are five different studies that show age does play a factor in quality of care.

"The older the physician or the further away from their training ... the more likely they are to be disciplined," he said.

Schnepper's attorney said that his age is not a factor, that he volunteers for review and continuing education and that his tremor is controlled by medication.