HUMAN PRETERM BIRTH IS ASSOCIATED WITH SYSTEMIC AND LOCAL CHANGES IN PROGESTERONE 17-BETA-ESTRADIOL RATIOS

OBJECTIVE: The purpose of this study was to determine whether human pr eterm birth is associated with changes in 17 beta-estradiol and proges terone concentrations in maternal plasma and amniotic fluid. STUDY DES IGN: Forty healthy women in preterm labor with singleton pregnancies a nd intact membranes at 32 to 36 weeks of gestation who underwent amnio centesis for evaluation of the microbiologic status of the amniotic ca vity were classified into the following two groups: 20 women who were delivered within 1 week from the amniocentesis (preterm delivery group ) and 20 who were delivered at term (term delivery group). Maternal pl asma and amniotic fluid concentrations of progesterone and 17 beta-est radiol were measured with sensitive and specific commercially availabl e radioimmunoassay kits. RESULTS: The median amniotic fluid concentrat ion of 17 beta-estradiol was significantly higher in women delivered p rematurely than in those who were delivered at term (1.5 ng/ml vs 0.9 ng/ml, p = 0.0001). Moreover, the median plasma 17 beta-estradiol conc entration was also significantly higher in the preterm delivery group than in the term group (14.1 ng/ml vs 6.9 ng/ml, p = 0.022). In contra st, no significant difference was found in amniotic fluid and plasma c oncentrations of progesterone between these two groups (24.5 ng/ml vs 27.5 ng/ml and 132.0 ng/ml vs 107.5 ng/ml, respectively). The median a mniotic fluid progesterone/17 beta-estradiol ratio was significantly l ower in the preterm delivery group than in those delivered at term (18 .4 vs 33.6, respectively, p = 0.0017). Moreover, the median plasma pro gesterone/17 beta-estradiol ratio was also significantly lower in the preterm delivery group than in the term group (9.8 vs 17.0, respective ly, p = 0.016). CONCLUSION: Human preterm birth is associated with sig nificantly lower progesterone/17 beta-estradiol ratios than those of w omen with preterm labor delivered at term.