Ovulation cycle monitoring methods

Details Ovulation cycle monitoring methods Ovulation cycle monitoring methods

1997-02-18

2002-06-11

Snay, Jeffrey (Department: 1743)

Chemistry: analytical and immunological testing

Pregnancy or ovulation

C600S551000

Reexamination Certificate

active

06403380

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to methods of monitoring the ovulation cycle in female mammals especially humans.
BACKGROUND TO THE INVENTION
The last few decades have seen much research conducted into ways of enhancing “natural” family planning, in which physiological parameters indicative of the status of the ovulation cycle are monitored. In our European patent specification EP-A-706346 we particularly describe such a method which uses the measurement of urinary estradiol or metabolites thereof, especially estrone-3-glucuronide (E3G), to provide a warning of the onset of the fertile phase. Related methods are described in our European patent specifications EP-A-656118, EP-A-656119 and EP-A-656120. Associated testing devices and test kits are described in these specifications, and also in our International patent specifications WO 95/13531 and WO 96/09553. A major objective of these earlier inventions is to provide monitoring methods which are tolerant to the variability in ovulation cycle parameters that occur between different individual subjects, and indeed within the same subject from one cycle to another. Especially for contraceptive purposes, a method should provide reliable fertility awareness despite such variability.
Even amongst a population of individual women experiencing apparently normal-length cycles (average 28 days), some individuals may exhibit extremely short cycle lengths, on an occasional or more frequent basis. The whole cycle can be compressed into 20 or 21 days, or in extreme instances an even shorter interval. The fertile phase (taking into account the time during which male sperm may remain viable) can commence exceptionally early. In a monitoring method which is looking for a rise in the urinary concentration of E3G or a similar metabolite, as an indicator of imminent entry into the fertile phase, the occurence of a very short cycle with very early commencement of the fertile phase may not easily be identified. Accordingly, as a further refinement, there is need for a “failsafe” mechanism to cope with unexpected short cycles.
GENERAL DESCRIPTION OF THE INVENTION
By the invention we provide a method of monitoring the human ovulation cycle, in which the cycle is immediately declared fertile if a body fluid test conducted on or about is day 6 of the cycle reveals a concentration of a fertility-related analyte which significantly differs from the concentration expected at that point. Taking as an example estradiol and its metabolites, it has hitherto been understood that about numerical days 5 to 7 of the cycle, counting from the onset of menses, the amount of estradiol and its metabolites circulating within the body, and hence excreted in urine and other fluids, is at or near its lowest level within the cyclic variation, and that it is some days thereafter before the amount rises to a level that is indicative of imminent ovulation. Although this is the normal situation, there are exceptions.
The invention provides a method of providing warning of the onset of the fertile phase of the human ovulation cycle, involving measurement in absolute or relative terms of the body fluid concentration of an analyte, such as estradiol or a metabolite thereof, characterised in that if in the current cycle a concentration measurement conducted at about the termination of menses reveals a body fluid concentration that is typical of that found in the body fluid of an average human female subject about 3 days prior to the time of ovulation during a 28-day cycle, the current cycle is immediately declared to be in its fertile phase.
A particular embodiment of the invention is a method of providing warning of the onset of the fertile phase of the human ovulation cycle, involving measurement in absolute or relative terms of the urinary concentration of E3G, characterised in that the fertile phase is declared immediately it an E3G measurement conducted at about the termination of menses reveals a concentration equal to or greater than a threshold concentration chosen in the range of about 25 to about 35 ng/ml.
The most appropriate time when the E3G concentration measurement is conducted is on at least one of numerical days 4 to 7 of the current cycle, and most preferably about day 6, counting from the onset of menses.
In a further embodiment, the invention provides a method of monitoring the fertility status of the mammalian ovulation cycle, involving determining a change in the body fluid concentration of an analyte the concentration of which alters as the fertile phase of the cycle approaches and wherein a concentration measurement is made during the interval spanning days 4 to 8 of the current cycle, characterised in that if the measurement reveals a concentration level at least equal to that expected about 3 days prior to the time of ovulation, based on measurements taken in one or more previous cycles in the same individual, the onset of the fertile phase is declared immediately. Normally this method involves determining a change in the body fluid concentration of estradiol or a metabolite thereof, such as E3G.
The invention also provides a method of monitoring the fertility status of the human ovulation cycle, involving determining a change in the urinary concentration of E3G during the early part of the cycle as a warning of the onset of the fertile phase, and wherein the E3G concentration is measured in relative or absolute terms on or about day 6 of the current cycle, characterised in that if the E3G concentration on or about day 6 of the current cycle is at least equal to the concentration attained in the same individual about 3 days prior to the time of ovulation during one or more previous cycles, the onset of the fertile phase in the current cycle is declared immediately.
For the purposes of illustration only, the invention will be described in relation to the measurement of urinary analytes, and especially “E3G” (estrone-3-glucuronide) and “LH” (luteinizing hormone).
In addition to estrone-3-glucuronide already mentioned, estradiol metabolites that can also be assayed for the purposes of the invention include estradiol-3-glucuronide, estradiol-17-glucuronide, estriol-3-glucuronide, estriol-16-glucuronide and (principally for non-human subjects) estrone-3-sulphate. As will be appreciated from the following description, the invention can readily be applied to data derived from the measurement of body fluid concentrations of other analytes of significance in relation to the status of the ovulation cycle. Generally, the most suitable analytes are hormones and their metabolites. Follicle stimulating hormone (FSH) is an example. Examples of alternative body fluids, which are relatively accessible, are saliva, crevicular fluid, sweat, sebum, tears and vaginal fluid. In principle, internal fluids, such as blood, can be used but are generally not preferred because they can only be accessed by invasive techniques.
The skilled reader will also appreciate that the body fluid “concentration” of the chosen analyte or analytes need not be measured in absolute terms, although this can of course be done if desired. Generally, it will be sufficient to assay an analyte in a manner which yields a signal, convertible to numerical data, related to the actual concentration, so that such data can be compared with similar data obtained at a different stage in the cycle to determine, for example, whether or not a significant change in actual concentration has occurred. Accordingly, where this specification and claims refer to the “concentration” of an analyte, this expression should be interpreted broadly.
An example of the context in which the present invention can be incorporated to advantage is a method of monitoring the fertility status of an individual female mammalian subject, involving testing of the body fluid concentration of an analyte, especially estradiol or a metabolite thereof, in which method said testing is conducted at least once during the interval spanning days 1 to 7 inclusive of the current cycle, to establish a reference concentration value or signal

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