A report released by the group on Wednesday day gives the state a "C" grade and says California's preterm birth rate is 10.7 percent. That's the ninth highest in the United States.
The state-by-state report card gives the country overall a "D" grade. A mother who gave birth to three premature babies says it's a silent epidemic.
"To leave the hospital at night and leave your child there in someone else's care, and a newborn, when your expectation is that you would take that child home in your arms is really heartbreaking," said Emma Goltz, a mother.
The March of Dimes says lack of insurance and smoking are among the factors that contribute to premature births, which have increased 20 percent nationwide since 1990.