myositis A rare muscle disorder characterized by persistent muscle swelling, inflammation and weakness, as well as other complications such as lung disease. The type affecting primarily muscles is also called polymyositis. Another form, derma- tomyositis, tends to be accompanied by a skin rash. An AUTOIMMUNE DISEASE, it affects twice as many women as men. It is diagnosed in just one of every 100,000 patients a year, but authorities suspect that many cases go unidentified. One survey indicated that the average patient sees seven physicians before receiving the correct diagnosis. Dermatomyositis in particular is associated with cancer, a malignancy occurring in about 15% of men patients over age 50 and in a smaller proportion of women, so patients need to be examined and monitored for malignancy. Interestingly, if a tumor is removed, the myositis often goes into remission. The principal treatment for myositis is prednisone, a corticosteroid. If it does not work, immunosuppressants such as methotrexate may be tried, or intravenous immunoglobulins. At this writing clinical trials are going on with a number of anticancer drugs. natural family planning Also biological birth control, calendar method, fertility awareness, periodic abstinence, rhythm method. A method of both birth control and pregnancy planning that is based on timing sexual intercourse so as to avoid (or seek out) a woman?s fertile period, that is, her time of OVULATION. For pre- venting pregnancy the couple abstains from vaginal intercourse during ovulation and, for more safety, several days before and afterward. Since an egg remains viable for only 24 hours after its release from the ovary, sperm, which can live 48 to 72 hours after ejaculation, must be present in the fallopian tube during that interval if fertilization is to take place.
Natural family planning still is the only means of birth control sanctioned by the Roman Catho- lic Church. Its success depends entirely on how closely one can estimate the time of ovulation and on avoiding intercourse during this fertile period. The interval between a menstrual period and ovu- lation is highly variable, both from one woman to the next and in the same woman (see MENSTRUAL CYCLE), but ovulation always occurs approximately 14 days before the start of the next menstrual period; thus one can tell when ovulation last took place, but only after the fact.
The four main methods of calculating the fertile period are: the calendar method, temperature method, cervical mucus method and combined or sympto-thermic method.
The calendar method, also called rhythm method, uses the length of past menstrual cycles to calculate the probable time of ovulation. For this purpose a woman must keep track of her cycle for at least six months. A cycle is said to begin on the first day of menstrual flow (day 1) and end on the last day before the next menstrual flow. One subtracts 18 from the shortest cycle to obtain the first fertile day and 11 from the longest cycle to obtain the last fertile day. To prevent pregnancy, one must avoid vaginal intercourse from the first fertile day through the last fertile day. The rest of the month is considered the safe period. Another mode of calcula- tion is counting to 15 from day 1 of a period; from that date subtract 6 and also add 6; these 13 days are the possible fertile ones, and the rest are ?safe.? The calendar method is considered the least reliable method of natural family planning and is totally useless for women with very irregular cycles, fol- lowing abortion or delivery, or during breast-feed- ing. In Europe a handheld computer, marketed as Persona, has been used to calculate pregnancy risk depending on the day of a woman?s menstrual cycle. Studies there suggest that with strict use it is about 94% effective. It is not available in the United States.
The temperature method, also called BASAL BODY TEMPERATURE (BBT), is based on the fact that pro- gesterone, released by the corpus luteum after ovu- lation, causes a measurable increase in basal body temperature, which remains raised until the next menstrual period. It too is an after-the-fact method of determining ovulation; that is, it provides evi- dence that ovulation took place, and when. It is somewhat more reliable than the calendar method and can be used by women with irregular men- strual cycles but is inaccurate following abortion or childbirth. Over a period of six to eight months, it may give a good indication of a woman?s pattern of ovulation.
The CERVICAL MUCUS METHOD is based on the fact that the cervical mucus in most women changes in consistency during the course of each menstrual cycle. After menstruation and before ovulation, the mucus is thick, sticky, opaque and scant. A few days before ovulation the amount of mucus increases and it becomes clear and more slippery, not unlike raw egg white. A woman checks her mucus manually, for degree of wetness (wettest at ovulation) and appearance, and keeps a record of changes in consistency to establish some kind of pattern for ovulation (she also can use one of sev- eral chemical tests on the mucus). This method has not been tested adequately over a long period of time, but it appears to work reasonably well once a woman has become thoroughly familiar with her own body patterns.
The combined or sympto-thermic method uses both changes in basal body temperature and changes in cervical mucus to estimate the fertile period. Tak- ing the strictest calculation of each, it appears to be the most reliable method of these four. However, none of them is as reliable as oral contraceptives, a diaphragm used with spermicide or intrauter- ine devices. (See table under CONTRACEPTIVE for a comparison.)
Natural family planning does have certain advan- tages. For birth control these methods all are totally reversible. They work either for planning a preg- nancy or for preventing one. They have no harmful side effects. They are free or require only very inexpensive equipment (but see below), and they involve the male partner?s cooperation. Their chief disadvantages are their limited reliability (depend- ing on how regular a woman?s cycles are) and the need for self-control exercised by both partners to prevent pregnancy (unless an alternative method of contraception is used during fertile periods). One other risk has been suggested. When natural family planning fails and unplanned pregnancy occurs, there appears to be a much higher than normal rate of miscarriage and birth defects. It is suspected that this is due to fertilization involving an old egg or an old sperm. The best chance for normal pregnancy is fertilization at the time of ovulation. A miscalculation by a couple using natural family planning may lead to fertilization 24 hours after ovulation, with increased risk of defects.
Various devices to measure hormonal changes and thereby predict ovulation have been devel- oped, mainly to help women who wish to become pregnant (see OVULATION), but they are not reliable for birth control.
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