BOSTON (AP) _ A Christian Science couple convicted of manslaughter in the death of their 2-year-old son have asked for a sentence reduction, charging that their probation is disruptive and unconstitutional.

Lawyers for David and Ginger Twitchell filed a memorandum Wednesday in Suffolk Superior Court seeking to reduce the couple's 10-year probation to five years and to eliminate regular medical checkups for their children.

The Twitchells were convicted July 4 of involuntary manslaughter for relying on spiritual healing to treat their son Robyn, who died of a bowel obstruction on April 8, 1986. The Twitchells have appealed the verdict.

Judge Sandra Hamlin had ordered the Twitchells, who now live in Brentwood, N.Y., to take their three remaining children for periodic checkups by a physician and get them immediate medical attention if they showed signs of serious illness.

Hamlin also ordered maximum probation supervision. New York officials believe that means the Twitchells must meet twice a week with a probation representative, Twitchell attorney Stephen Lyons told the Boston Herald.

''I don't think Judge Hamlin intended the probation to be that intrusive,'' Lyons said.

In an affidavit filed with the court, Mrs. Twitchell, 34, said her two youngest children have had medical checkups and the oldest has an appointment this week.

''Our life as a family would be less disrupted and more calm if the number of probation visits were reduced and if such visits were at our home only or if we could have the conversations regarding medical care by telephone,'' she said.

The Twitchell children range in age from 1 to 9 years old.