A Fairfax County jury has awarded $1 million to a 5-year-old Annandale left mentally and physically retarded after delivery by her obstetrician in what is believed to be the largest award in the county circuit court's history.

The jury ordered the obstetrician, Dr. Louis Q. Pugsley of Fairfax, to pay the amount to Tana Marie Durenec, daughter of Peter and Gabriela Durenec, who came to this country from Czechoslovakia in the 1960s. The Durenecs had also sued Fairfax Hospital, where Tana was delivered on Sept. 23, 1975, but the jury rejected that negligence claim.

Pugsley, while in the doctors' lounge, prescribed three doses of a labor-stimulating drug for Gabriela Durenec, according to testimony. The Durenecs' lawyers argued that Pugsley should have "personally evaluated" the expectant mother during the four hours before birth and that he did not.

They maintained that Tana should have been delivered by caesarian section. Pugsley testified that an emergency developed, and he was forced to deliver with forceps.

During delivery, Tana suffered a fractured skull and brain damage, according to testimony.

Witnesses testifies that Tana's I.Q. is 53 and that she would never rise above a second-grade level. Tana, who was given a neurological exam in front of the jury, will require therapy for the rest of her life and can never be left alone, expert witnesses said.

"The Durenecs' older daughter was delivered normally by Pugsley.

Pugsley has 30 days to appeal the jury's verdict. Circuit Court Judge Burch Millsay can set aside verdict, if he decides it is excessive, and order a new trial.