Περίληψη:
Considering that preterm birth accounts for about 6-10% of all births
in Western countries and of more than 65% of all perinatal deaths,
elucidation of the particularly complicated mechanisms of labor is
essential for determination of appropriate and effective therapeutic
interventions. Labor in humans results from a complex interplay of fetal
and maternal factors, which act upon the uterus to trigger pathways
leading gradually to a coordinated cervical ripening and myometrial
contractility. Although the exact mechanism of labor still remains
uncertain, several components have been identified and described in
detail. Based on the major role played by the human placenta in
pregnancy and the cascade of labor processes activated via placental
mediators exerting endocrine, paracrine, and autocrine actions, this
review article has aimed at presenting the role of these mediators in
term and preterm labor and the molecular pathways of their actions. Some
of the aforementioned mediators are involved in myometrial activation
and preparation and others in myometrial stimulation leading to
delivery. In the early stages of pregnancy, myometrial molecules, like
progesterone, nitric oxide, and relaxin, contribute to the retention of
pregnancy. At late stages of gestation, fetal hypothalamus maturation
signals act on the placenta causing the production of hormones,
including CRH, in an endocrine manner; the signals then enhance
paracrinically the production of more hormones, such as estrogens and
neuropeptides, that contribute to cervical ripening and uterine
contractility. These molecules act directly on the myometrium through
specific receptors, while cytokines and multiple growth factors are also
produced, additionally contributing to labor. In situations leading to
preterm labor, as in maternal stress and fetal infection, cytokines
trigger placental signaling sooner, thus leading to preterm birth.
Συγγραφείς:
Iliodromiti, Zoe
Antonakopoulos, Nikolaos
Sifakis, Stavros and
Tsikouras, Panagiotis
Daniilidis, Angelos
Dafopoulos,
Kostantinos
Botsis, Dimitrios
Vrachnis, Nikolaos
