A 29-year-old Fairfax woman defied odds of 700,000 to 1 yesterday by giving birth to quadruplets without the help of fertility drugs, a Fairfax Hospital spokesman said.

Cindy Sonderquist, a house painter from Burke, delivered three boys and one girl by cesarean section between 3:41 and 3:44 a.m. The infants, who have not yet been named, are all in the hospital's neonatal intensive care section.

The boys, whose weights vary from 2 pounds 9 ounces, to 4 pounds 2 ounces, were listed in serious condition and were breathing with the aid of ventilators. The girl, who weighed 3 pounds 5 ounces, was in good condition, hospital officials said.

Sonderquist has a 10-year-old daughter from a previous marriage. Her husband, John Fewell, a 35-year-old convenience store manager, has four children from a previous marriage, ranging from age 6 to 16, the hospital spokesman said.

The babies were delivered a month prematurely by Dr. Thomas E. Schmitt, who delivered Fairfax Hospital's only other set of quadruplets -- those born on Sept. 27, 1984, to Susan and Geoffrey King of Arlington.

Schmitt also defied the odds: According to the laws of probability, the average time between deliveries of quadruplets by the same obstetrician should be 4,800 years.