Maternity clothes for the office

There is an emerging ''dress for success'' ethic for pregnant working women. There's no need to look out of place at work while pregnant. Maternity shops carry elegant floral print dresses, expensive-looking blouses, plaid suits with jackets and skirts, and blazers. There are also jumpers, some in casual corduroy.

''Each season we see more clothes for working women,'' says Jackie Curran, owner of the Lady Madonna maternity boutique in Boston. Her customers represent a wide variety of professions, including secretaries, lawyers, a television news broadcaster, and a politician, as well as homemakers.

''They let us know if our clothes are not dressy or professional enough,'' Mrs. Curran says. ''One woman came in and said, 'I'm a lawyer and when I am in that courtroom, I need to look tops.' She is typical of our customers.''

Some pregnant women reason that since pregnancy lasts only nine months, it isn't worth it to spend much money on clothes. Working women don't always have that option.

Anne Johnson of Seattle, who is pregnant with her second child, says, ''When I was pregnant before, I bought inexpensive corduroy pants. I just didn't feel I looked pretty.''

Now she is buying polished-looking work clothes, as well as attractive casual clothes. One of her choices is a crisp-looking fall plaid dress with a round collar and bow tie to take her to work. Mrs. Johnson recently attended a football game in a pink oxford cloth shirt, white pants, and a pink and gray argyle sweater.

Investing in maternity clothes can be expensive. ''It's like buying a whole new wardrobe,'' says one expectant working mother. Lady Madonna's prices range from medium to expensive, but Mrs. Curran reports that less expensive manufacturers are becoming competitive and producing classy working clothes.

One pregnant woman looks for bargains at a secondhand maternity shop. And, because she is quite small, she shops for good-looking jumpers in junior departments.