A jury has awarded $750,000 in compensatory damages to a Culpeper County, Va., couple who sued a local obstetrician for medical malpractice in the death of a newborn son and injury to his mother.

The award, the largest permissible under Virginia law, was made in a case against Dr. Parviz Modaber, who has practiced in Culpeper since 1976. In their complaint, the couple contended that Modaber failed to provide proper prenatal care to the mother and failed to arrive at the hospital in time to save the baby, despite three phone calls by attending nurses.

As a result, the complaint alleged, the baby died and the mother's life was "recklessly" jeopardized. The award, made Sept. 24, comes after a state Malpractice Review Panel considered the case last year and unanimously found that the standard of care given by Modaber was inappropriate and was the "proximate cause" of the infant's death.

Modaber could not be reached for comment yesterday. However, his attorney, Harrison Pledger of McLean, said he will ask for a new trial. Pledger said he had presented expert testimony "that there was no deviation from accepted standards of care" by Modaber in his handling of the case, but declined further comment. According to the complaint by the mother, Jessie Marie Kelley, and the father, Ronald, of Rixeyville, Va., Mrs. Kelley had two previous pregnancies in which she suffered from toxemia, a pregnancy-induced condition that causes extremely high blood pressure and can endanger the life of mother and child unless carefully treated.

Modaber, according to the complaint, was aware of Kelley's history when, in early November 1978, he diagnosed her as suffering from toxemia again. In view of that diagnosis, the Kelleys' attorneys argued in court, Kelley should have been promptly hospitalized on Nov. 21 when tests revealed that her condition had worsened. Modaber did not put her in a hospital.

On Nov. 27, Kelley went into labor, five weeks prematurely. According to the complaint, these events followed:

Mrs. Kelley called Modaber's answering service and was told to go to Culpeper Memorial Hospital. The answering service notified Modaber at 5:15 a.m. that Kelley was on her way. At the hospital, Kelley's blood pressure was found to be extremely high. Modaber was called at home and informed of her condition.

At 6:50 a.m., Modaber was called a third time and told that the baby was suffering "fetal distress" and that its heartbeat was failing. At 7:10 a.m., when a nurse called to report that fetal distress continued, Modaber left for the hospital.

Modaber examined Kelley briefly and left the room. By the time he returned, according to the testimony of hospital medical personnel, Kelley had delivered a stillborn boy while waiting in a hallway on the way to the operating room.

Modaber was subsequently barred from using the hospital, because hospital officials said he needs more medical training. Modaber, an Iranian by birth and a naturalized American citizen, has filed suit to regain hospital privileges, which he alleges were revoked largely because of American anti-Iranian sentiment.