Fetal
peptide hormones are essential for the development of fetus, which increase in accordance with pregnancy term. Concentration of these
hormones within the feto-placental unit is normally higher than that of maternal circulation. Since these
hormones are biologically active, the leakage of these
hormones into the maternal circulation is regulated by degradation activity by placental
aminopeptidases, in order to maintain the balance between carriage of pregnancy and onset of labor.Because the concentration of these
hormones, being regulated by the amount of endogenous production and by physiological degradation by
enzymes in the blood and tissue, the balance between production and degradation is a definitive
element for maintaining normal gestation and term delivery.The changes of the balance between fetal
angiotensin II (A-II) and
vasopressin (AVP) andA-II and AVP degrading
enzymes, between
aminopeptidase A (APA) and
placental leucine aminopeptidase( P-LAP) - in the placenta and maternal blood due to fetal stress such as
hypoxia - are the provable causes of
preeclampsia or
preterm labor.Induction of APA and P-LAP by
estradiol benzoate (E2) and
progesterone (P) from placenta has been demonstrated. They are involved in the regulation of fetal
peptide hormones via placental
aminopeptidases in homeostasis of pregnancy.Recently it was shown that both APA and P-LAP could be potentially safe and effective drugs for
preeclampsia and
preterm labor. The authors' proposed sex
steroid treatment with dose increasing manner by gestational week (sex
steroid treatment) for severe
preeclampsia and
preterm labor could be candidates replacing conventional treatments. In light of lacking safe and effective medication, the proposed sex
steroid treatment is worthwhile for the prospective controlled studies for the treatment of both
preeclampsia and
preterm labor.