A pregnant Julia Roberts (search) was hospitalized over the weekend after experiencing a series of early contractions, People magazine reported.

The actress was accompanied by her husband, Danny Moder (search), when she was admitted to an undisclosed hospital Saturday night. The contractions eventually stopped, but she remained under observation, People reported Tuesday.

Messages left Wednesday by The Associated Press for Roberts' publicist, Marcy Engleman, weren't immediately returned.

The 36-year-old movie star is expecting twins — a boy and a girl — in early January.

People, citing unnamed sources, said Roberts' condition wasn't serious, but that her doctors had advised bed rest until her due date.

She had been planning to attend a baby shower Sunday with family and friends. The shower was moved to her room at the hospital, People reported.

Roberts, who won the best actress Oscar in 2001 for "Erin Brockovich," married Moder in July 2002 at her home in New Mexico. The twins would be the first children for Roberts, who starred in 1990's "Pretty Woman."

Her upcoming films include "Ocean's Twelve" and "Closer."