Ar. Martinez et al., PREDICTION AND DETECTION OF THE FERTILE PERIOD - THE MARKERS, International journal of fertility and menopausal studies, 40(3), 1995, pp. 139-155
The occurrence and duration of the fertile period in women are strictl
y related to the time of ovulation. Since the only positive confirmati
on of ovulation is the identification of an ovum in the female reprodu
ctive tract or the subsequent detection of a pregnancy, the prediction
and detection of its occurrence have to be based on markers or indica
tors that lie at varying physiological distances from ovulation itself
. These may be variations in hormones and other substances that can be
detected in different body fluids or the evidence of their effects on
specific target organs. Recent advances in the knowledge of reproduct
ive physiology have allowed the identification of distinct substances
and biological phenomena that accompany the occurrence of the fertile
period. This article is intended to update and classify the available
fertility markers based on their particular nature and modality of exp
ression and, additionally, consider the temporal relationship between
the appearance of their specific signals and the time of ovulation. Co
nsequently, those indicators directly related to changes at the ovaria
n level were defined as direct markers, including ovarian morphology,
the reproductive hormones, and the intraovarian regulatory proteins, w
hereas those reflecting variations observed in different target organs
were considered indirect markers, and were further qualified as bioch
emical, biophysical, and clinical. Subsequently, fertility markers wer
e classified as prospective, immediate, or retrospective, depending on
whether they allow the prediction, detection, or confirmation of the
ovulatory event, respectively.