16 days, produetion of the hormone progesterone,
FERTILITY INDICATOR which caused the temperature to rise initially, decreases
and BBT falls.
The present invention relates to an electronic fertility Success in avoiding pregnancy with the BBT method
indicator for detecting and recording the status of a 5 depends on how accurately the temperature is taken
womens menstrual cycle. and recorded and how well the shift correlates with
Despite the advances of modern medicine, the only ovulation,
method of birth control which is completely safe and Because it is the shift in temperature rather than the
completely effective is complete sexual abstinence. temperature itself which must be noted, the readings
Only in the last half century has knowledge of female 10 must be taken daily and always at the same time. Ide
reproductive physiology been systematically applied to ally, the temperature should be taken in the morning
the development of a technique for birth control in while still in bed after at least five hours of uninter
which sexual abstinence is timed to coincide with the rupted sleep and before eating, drinking, or extended
fertile phase of the woman's menstrual cycle. Variously conversation, since any activity at all can raise BBT.
referred to as rhythm, or the safe period, this method 15 Temperature readings may be taken either orally, rec
usually requires that couples abstain from intercourse tally, or vaginally as long as the same method is always
for at least eight days approximately at midcycle be- used.
tween the menses under this system. It was though that The major drawback of the temperature measuring
ovulation, or release of the ovum from the ovary, oc- method is readily apparent. It cannot predict in advance
curred once per cycle; that the ovum was susceptible to 20 when ovulation will take place.
fertilization for only 24 hours; and that the sperm depos- The fertility indicator of the present invention is an
ited in the female reproductive tract was capable of electronic instrument intended to record at a specific
fertilizing the ovum for only about 72 hours. Thus, if time of day the minimum or maximum temperature of
intercourse did not occur just before and during this the patient's body. Multiple readings on subsequent
period, the sperm could not fertilize the ovum and con- 25 days will be stored in the indicator's memory for later
ception could not take place. This in theory, is a safe readout, which will demonstrate the existence of a bi
and simple method of birth control. phasic curve or the absence of one.
The difficulty in practicing rhythm is that ovulation The inventive fertility indicator, with its extraordinormally occurs about 14 days prior to the next men- narily accurate temperature readings and completely strual period but not necessarily 14 days after the previ- 30 accurate memory and readout, will eliminate these comous menstrual period. Different techniques have been mon difficulties of conventional birth control methods, devised for predicting ovulation in advance or for iden- In the interest of obtaining the most readings of basal tifyng its occurrence immediately afterwards, but each body temperature, the fertility indicator has been deraises different problems and no method is universally signed in one embodiment for insertion into the vagina applicable. If all women had regular menstrual cycles, 35 where body temperature fluctuations will be accurately calendar rhythm would be reliable. They could readily reflected.
known on a calendar the safe days after and before The vagina as a location is anatomically sound and ovulation and restrict intercourse accordingly. But cy- psychologically appropriate. In this embodiment, the cles vary by an average of about 7 to 13 days for the size of the fertility indicator is similar to the commonly peak reproductive years and by even greater margins 40 used vaginal tampons and the attached string. It is defer girls in their teens and women approaching meno- signed after the fashion of the tampon, and provides an pause. For those women desiring to become pregnant, ease of insertion and removal, in a manner already unthey can also never be sure of ovulation time best for derstood by the majority of patients. The program for intercourse. Temperature rhythm relies on changes in use calls for insertion of the fertility indicator at bedtime basal body temperature (BBT) to identify the time of 45 and its removal on awakening.
ovulation. A rise of about 0.3° to 0.5° Centigrade, or The fertility indicator (when used as a vaginal tam
0.5° to 1.0° Fahrenheit, occurs in the basal body temper- pon) will record the temperature at a specific time, for
ature at about the time of ovulation. The effectiveness example, 5:00 AM which will be consistent throughout
of temperature rhythm depends on how carefully the the period of observation. If the fertility indicator is not
temperature is recorded, and how well this temperature 50 within the vagina at the time of recording, this will be
correlates with the actual time of ovulation. Then if obvious on the temperature recorded. The patient need
intercourse is avoided until three days after this temper- only keep a sequential record of unusual influences on
ature rise and takes place only during the remaining ten basal body temperature such as: fever, late night activ
to twelve days before the menses, there is no likelihood ity, early rising, etc.
of pregnancy. 55 The fertility indicator of the present invention is a Unlike the calendar method, which depends primar- microprocessor based thermometer capable of sensing ily on the regularity of the menstrual cycle, the thermal and recording temperature to an accuracy of 1/20° F. or temperature method depends upon identification of a within a range of 90°-110° F. The device can be packsingle event—the rise in basal body temperature (BBT). aged in the form of a table top version or a wrist watch This occurs at the time of ovulation as a result of the 60 or necklace version which includes a digital LED diselevated progesterone level. The basal body tempera- play calendar, alarm and time read-out, and also a fever ture refers to the temperature of the body at complete indicator for general purposes. When the temperature is rest. to be taken at a predetermined set time, an alarm on the The rise in BBT is small, only about 0.5° to 1.0° Fahr- device will sound alerting the person to apply one of the enheit (0.3° to 0.5° Centigrade). In most cases it is 65 temperature sensing devices to the body to begin the abrupt but sometimes takes as long as four or five days temperature reading. After a predetermined set interval to stabilize. If fertilization does not take place, the cor- and after the temperature has risen and stabilized, it is pus luteum ceases to function, after approximately 13 to recorded in a program storage unit which keeps a re