Everything seemed to go well until the end of the first week. When Danielle and her husband, John, visited the unit, Alexis looked fine, but Katherine appeared mottled and pale. Panicked, Danielle found a nurse, and testing confirmed that Katherine was in profound shock due to necrotizing enterocolitis, a devastating intestinal complication that affects premature babies. The infant’s blood had turned acidic. An X-ray indicated a tear in her bowel. Just after midnight, Katherine was taken by ambulance to Children’s Hospital Boston.

Extremely premature infants such as Katherine and Alexis are entirely unprepared to live outside their mother’s womb. After only 30 weeks of gestation, the newborn heart isn’t fully developed, and the intestines can’t easily digest breast milk or formula. At that age, a baby’s brain often doesn’t remember to breathe. In 1963, when President John F. Kennedy’s son, Patrick, was born prematurely, the only thing to do was “monitor the infant’s blood chemistry,” as a newspaper of the day put it. Patrick Kennedy died after two days. By the time Katherine Bellerose was being cared for in the same hospital, however, new treatments had increased survival rates in very low birth weight infants to 96 percent.

Still, at Children’s Hospital, Katherine struggled to survive. Surgeons made a last-ditch effort to save her life by removing her colon, in the hope that this would halt further damage. She failed to improve. Multiple rounds of CPR were performed.

At 5:22 a.m. on June 21, 2004, 8-day-old Katherine Bellerose was declared dead.

 In the days and weeks ahead, Danielle tried to get someone to explain why no one had diagnosed Katherine’s condition sooner. She made three requests to meet with the caregivers from Beth Israel. Promises were made, she says, yet no meeting materialized. Later, when Danielle contacted the hospital to get Katherine’s medical records, she recalls a clerk saying no such patient had ever been treated (a problem later ascribed to a paperwork error). Danielle began to think the hospital was hiding something.

In time, Danielle got in touch with Lubin & Meyer, a Boston law firm perhaps best known for winning $40 million in a 2005 birth-injury case, the largest malpractice award in Massachusetts history.

Danielle’s attorneys, William Thompson and Elizabeth Cranford, obtained Katherine’s medical records, then asked a doctor and professional expert witness to review them. As is customary, the expert never spoke with the infant’s physicians, nor did she see a need to interview the Bellerose family while preparing her report. The 10-page document, issued two years after Katherine’s death, is not nuanced, even though the early warning signs of enterocolitis — such as a slight increase in the size of the abdomen and higher breathing rate — are often nonspecific and present in babies who go on to do fine. It claimed Katherine suffered a “premature and preventable death” from necrotizing enterocolitis that occurred as a “direct result” of “deviations from the accepted standards of care.” Reading the report steeled Danielle Bellerose against the Beth Israel doctors and solidified her suspicion that their negligence had killed her daughter. In 2006, her attorneys filed a lawsuit against six of the doctors and nurses who had treated Katherine.