For women in their twenties or thirties who want to ease their passage through mid-life, the experts recommend:

*Build bone mass. Bones continue to accumulate mass until about age 35. Then the process reverses. For women, whose bones are 30 percent smaller than men, the bone loss can be very severe -- particularly three to seven years after menopause. Often osteoporosis results, a debilitating condition characterized by thin, brittle bones. Some 15 to 20 million Americans, most of them women, are afflicted.

One way to prevent osteoporosis is to build enough bone mass before age 35 to compensate for the post-menopausal loss. In April, a National Institutes of Health conference recommended that premenopausal women and women taking estrogen consume about 1,000 mg. of calcium per day -- roughly three 8-ounce glasses of skim milk. After menopause, women need about 1,500 mg. of calcium daily. Supplements, such as calcium carbonate and calcium gluconate, can be used to meet this daily requirement, particularly for those who cannot tolerate milk or milk products.

Exercise also helps build bone and retard bone loss. Estrogen therapy is another way for women to cut bone loss after menopause, although this increases the risk of developing cancer.

*Stop smoking. Women who smoke generally experience menopause earlier than non-smokers. On average, heavy cigarette smokers go through menopause earlier than light-smokers; light smokers experience menopause earlier than ex-smokers, and ex-smokers go through menopause before non-smokers. Preliminary results from the Norwegian Female Climacteric Study also suggest that smokers experience more hot flashes and more sweating during menopause than non-smokers.

*Education. In our culture, much negative folklore surrounds menopause. Women in India and other far-east countries experience a less-traumatic life change.

*A supportive spouse. "Men should be aware that some of the reactions of women during menopause are related to how we behave towards them," says Norwegian psychologist Arne Holte. "Men should use their time to listen more." -- Sally Squires