Bonnie Marie Frustaci, the weakest of four remaining septuplets born to a California schoolteacher 19 days ago, died in her parents' arms today from lung and heart failure, hospital officials said.

Doctors had said for several days that they did not think the tiny girl, who weighed 28 ounces at birth, would survive.

But she held on to life longer than expected as her parents and other family members maintained a vigil in the neonatal intensive care unit of Children's Hospital of Orange County.

Her death at 12:25 p.m., attributed to the strain of a lung disease common to severely premature infants, leaves three surviving Frustaci septuplets: Patricia Ann, Stephen Earl and Richard Charles. They remain in critical condition with the same ailment, hyaline membrane disease, but all are said to have good chances of survival.

A hospital spokesman said Bonnie Marie's parents, Patti and Sam Frustaci, "were holding her at the time of death."

Sam Frustaci, 32, an industrial steam equipment salesman and a member of the Church of Jesus Christ of Latter-day Saints, released this statement:

"Bonnie Marie lasted a week longer than they gave her. She fought long and hard. I can honestly say she was a real fighter, possessed of tremendous spirit. She joins her brothers and sisters in heaven."

Although at least six sets of sextuplets are reported to be alive in the world, no more than five children born to the same woman at the same time have survived infancy in the United States.

Carrying seven babies at a time puts severe strain on the mother's ability to provide sufficient nutrients for all and raises the chances of dangerous high blood pressure and premature delivery.

According to Helen Kirk, a Galveston, Tex., expert on multiple births, the survival of even one Frustaci septuplet would be the first such instance in the United States. Previous sets of septuplets reported in Pennsylvania in 1899, Boston in 1966 and San Francisco in 1972 died shortly after birth or were stillborn, she said.

Patti Frustaci, 30, had been taking the fertility drug Pergonal. Some doctors have suggested that more careful monitoring could have prevented conception of seven babies, but the clinic that administered the drug has indicated that it followed standard procedures.

At least 5 percent of women taking Pergonal conceive three or more children. The Frustacis have a 14-month-old son, also conceived after they used Pergonal.

Patti Frustaci was hospitalized in March and gave birth to six live babies and one stillborn girl, Christina Elizabeth, May 21. One child, David Anthony, died 64 hours later and another, James Martin, died Thursday after 16 days of struggle with the lung disease.

Each Frustaci infant was born 12 weeks prematurely and weighs less than 2 pounds. Each lacks a substance called surfactant, which helps prevent lung sacs from collapsing.

All three surviving babies are breathing with the aid of respirators and are expected to remain in the hospital at least until August.

A hospital spokesman said a private funeral, similar to that conducted for the other infants, is planned for Bonnie Marie.