BOSTON (AP) _ For most couples, starting a family is a private affair _ a candlelit dinner, romantic music, maybe some silky lingerie.

Not for four Massachusetts couples.

The couples are competing to conceive the nation's first millennium baby. They're in separate rooms in a Boston hotel today, considered the optimal conception day for a Jan. 1, 2000 birth.

If one of the couples bears the first baby born in the United States next year, the parents will receive a check for $1 million, courtesy of radio station WJMN.

The couples _ Darren and Saundra Mendalka of Winthrop, Cochise and Laurel Pearsen of Boston, Derrick and Bobbi Milso of Weymouth, and Greg and Trina Hackett of Lynn _ were selected out of hundreds of radio station callers.

Any birth must be natural _ no Caesarean sections or inducements allowed.

``I guess it's normally not so public,'' Mrs. Mendalka said. ``I called my mother and I said, `How does it feel to have a daughter that's going to be in the public and everybody knows that she's going to have sex tomorrow?'''

The odds against the aspiring parents are long. Obstetricians warn that babies arrive when they want over a period of weeks, not seconds.