By the fourth or fifth month of approaching parenthood you get used to being called ''Big Momma.'' By the time the seventh month rolls into view you're even able to laugh along with the jokesters who want to know how many watermelon seeds you've swallowed lately.
Other people's comments aren't so difficult to deal with. It's your own perceptions of changing proportions that are hard to avoid.
The first awakening probably came the Saturday I discovered I'd outgrown my husband's cast-off jeans - the pair he stopped wearing the summer he lost 20 pounds. Those pants had become a comfortable weekend refuge over a number of months and somehow made me feel at home with the rest of the loosely attired crowd down at the town dump.
I began making the rounds of stylish maternity boutiques in the area, but after spending several weekends in dressing rooms, trying on appliqued tents with designer labels like ''Lady in Waiting'' and ''Meanwhile Mixables,'' I only felt less svelte. I retreated to our attic to dig through the piles of clothing that had accumulated over the years and finally came up with a pair of gray sweat pants left over from my husband's physical education courses in college. Minus the original waist drawstring, they were just the right fit, which was no fit at all. Since then, I've splurged on two more pairs of extra larges from the Army & Navy store, one in camouflage green for house chores, and another in slightly nattier navy blue that my husband likes to refer to as my ''dress sweats.''
The change in size can't compare with the change in center of gravity, however. Practically overnight, I've developed an odd gait reminiscent of a camel trying out its first pair of roller skates. To add to the disorientation, other familiar landmarks have unaccountably taken on new dimensions. Doorways and hallways are suddenly narrower, and I've begun to approach revolving doors with the practiced eye of an Olympian lining up for a record-breaking broad jump.
The only embarrassing moment so far came the morning I held up the departure of a commuter airline shuttle while the stewardess folded back several seats so I could make my way down the aisle. Then there was the afternoon when I began talking to myself. Actually, I was addressing the budding young athlete-in-residence who'd recently taken up indoor rugby, but no one else in the crowded elevator knew that. Just as the other conversations reached an unexpected lull, I heard myself whispering a stern ''Now cut that out!'' The rest of the ride was so quiet you could have heard a baby blush.
Stunned silence is only one of the responses I've experienced in the past few months, however. More surprising are the offers of seats on crowded subways and buses. Surprising because they invariably come from women whose husbands tend to back out of doors rather than hold them open for me, perhaps because they think the condition may be catching.
Thankfully, there's some comfort to be found in numbers. While we were waiting for our names to be called the other night in a favorite restaurant, we counted seven mothers-to-be leaving the lobby in a period of ten minutes.
''Parenthood,'' my husband sighed when we were finally seated at our table. ''I guess it grows on you.''