Plasma progesterone, estradiol, and unconjugated estriol concentrations in twin pregnancies: Relation with cervical length and preterm delivery.

INTRODUCTION: The aim of this study was to examine the association between plasma hormone concentrations, cervical length, and preterm delivery in twin pregnancies, including the effect of progesterone treatment. MATERIAL AND METHODS: This study included 191 women pregnant with twins from a randomized placebo-controlled trial. A baseline blood sample was collected at 18-24 weeks before treatment with vaginal progesterone (n = 95) or placebo pessaries (n = 96), and 167 (87.4%) women had a second sample collected after 4-8 weeks of treatment. At baseline, 155 (81.2%) women had their cervical length measured. Progesterone, estradiol, and unconjugated estriol concentration was measured, and the association between hormone concentrations, cervical length, and gestational age at delivery was examined. Hormone concentrations were compared in the placebo and progesterone group. Statistical analysis included Spearman's rho, Mann-Whitney U test, Cuzick's test for trends, and linear regression analyses. RESULTS: A short cervical length was associated with preterm delivery. Cervical length and hormone concentrations were not associated (Spearman's rho; progesterone -.05, estradiol .04, estriol .08). Decreasing gestational age at delivery was associated with higher progesterone and estradiol concentrations at baseline (P trend; progesterone 0.04, estradiol 0.02) but not in the second sample or in the weekly change between samples. Progesterone treatment did not increase the progesterone concentration. CONCLUSIONS: Plasma concentrations of progesterone, estradiol, and unconjugated estriol at 18-24 weeks are not associated with cervical length or preterm delivery in twin pregnancies. Vaginal progesterone treatment does not increase the circulating progesterone concentration in twin pregnancies. Cervical length, but not hormone concentration, is predictive of preterm delivery in twin gestations.

Progestins used in hormonal replacement therapy display different effects in coronary arteries from New Zealand white rabbits.

OBJECTIVES: The aim of this study was in an animal model to assess the vascular effects of different progestins commonly used in hormonal replacement treatment. METHODS: Fifty-six non-atherosclerotic, ovariectomized New Zealand white rabbits were randomized into seven groups: (1) medroxyprogesterone acetate (MPA), (2) norethisterone acetate (NETA), (3) conjugated equine estrogens (CEE), (4) 17-beta-estradiol (E2), (5) MPA+CEE , (6) NETA+E2 , (7) or placebo (n=8) and given hormonal treatment through the diet for 4 weeks. Ring segments from the left proximal coronary artery and from the distal part of the left anterior descending coronary artery were microdissected and mounted for isometric tension recordings in a myograph. The vasoconstrictory responses induced by potassium, endothelin-1, calcium and Nw-nitro-L-arginine methyl ester, and the vasodilatory response induced by acetylcholine and sodiumnitroprusside were investigated. The maximum contraction/relaxation (Emax) and the concentration required to induce half the maximum response (EC50) were determined. EC50 values were expressed as the negative logarithm to the molar concentration, pD2=-log EC50. RESULTS: Treatment with MPA alone caused when compared to treatment with NETA an increase in tension development in the distal coronary artery after the addition of potassium ( 6.36+/-0.36 versus 4.31+/-0.42 P<0.005) (single dose response, mN/mm, mean+/-S.E.M.) and endothelin-1 (9.41+/-0.82 versus 6.43+/-0.73 P<0.05) (Emax, mN/mm, mean+/-S.E.M.). Treatment with MPA compared to placebo caused an endothelin-1 induced increase of Emax in the distal coronary artery (9.21+/-0.87 versus 6.51+/-0.65 P<0.05) and a calcium induced increase of pD2 in both coronary arteries (2.98+/-0.19 versus 2.42+/-0.12 P<0.05, proximal coronary artery) (3.26+/-0.09 versus 2.9+/-0.1 P<0.05, distal coronary artery) (pD2, mean+/-S.E.M.). Treatment with NETA compared to placebo in the proximal coronary artery, after the addition of sodiumnitroprusside caused a decrease of pD2 (5.33+/-0.19 versus 5.94+/-0.13 P<0.05). Treatment with E2 compared to treatment with CEE in the proximal coronary artery caused a decrease of pD2 after the addition of sodiumnitroprusside (5.00+/-0.16 versus 5.77+/-0.28 P<0.05). No significant differences were found between MPA+CEE and NETA+E2. CONCLUSION: Treatment with MPA alone seems to enhance the contractile response to potassium and endothelin-1 in the distal coronary artery compared to NETA, indicating that different progestins used in hormonal replacement treatment may display different effects on contractile functions of coronary arteries.