Lack of normal increase in saliva estriol/progesterone ratio in women with labor induced at 42 weeks' gestation.

Saliva specimens were collected approximately every 6 hours from day 280 to day 294 by 16 women who labored on day 294. There was a normal rise in the mean saliva estriol/progesterone ratio in the six who went into labor spontaneously but no change in the 10 whose labor was induced.     

The increase in plasma and saliva cortisol levels in pregnancy is not due to the increase in corticosteroid-binding globulin levels

Total and free cortisol levels are significantly elevated in pregnancy, but the reasons for this are not clear. The relationships between the diurnal variation in saliva (free) cortisol and baseline levels of total cortisol, corticosterone-binding globulin (CBG), progesterone, and estrogens were studied in several groups of women (normal nonpregnant, taking a combined oral contraceptive pill, after superovulation therapy, during early and late pregnancy, and postpartum). Saliva cortisol levels were significantly elevated in late pregnancy throughout the day, with preservation of diurnal variation. Total cortisol and CBG levels were also significantly raised in pregnancy, but total cortisol levels were normal in women taking a combined oral contraceptive pill in spite of significantly elevated CBG. There was no relationship between saliva cortisol and progesterone levels, and it is unlikely that the increase in cortisol is due to displacement of cortisol from CBG by progesterone. Cortisol levels fell slowly postpartum over several days, making it improbable that the increase in cortisol is solely due to elevated CRH levels. It appears that increased free and total cortisol levels in pregnancy are related to resetting of the sensitivity of the hypothalamic-pituitary-adrenal axis and not merely to raised CBG, progesterone, or CRH levels.     

Oestriol and oestradiol increase cell to cell communication and connexin43 protein expression in human myometrium.

Oestradiol increases the protein expression of connexin43 (Cx43) gap junctions in myometrium but the effect of oestriol on gap junction expression has not been described previously. Oestriol is the most abundant free oestrogen in pregnant women and there is a marked surge in oestriol concentrations before term and idiopathic preterm labour. In order to determine whether oestriol may have a physiological action on the myometrium, cultured human myometrial cells obtained from non-pregnant hysterectomy specimens were exposed to 10 nmol/l oestradiol or oestriol. Intercellular communication between myometrial cells was investigated by microinjection of confluent cultured cells with the gap junction-permeant tracer Cascade Blue. There was a progressive increase in coupling after exposure to oestradiol or oestriol (P < 0.0005). An increase in Cx43 protein expression was demonstrated by immunocytochemistry after 1 h (P < 0.01) and 3 days (P < 0.01) exposure, and by Western blotting after 1 h (P < 0.01) and 3 days (P < 0.05) exposure, to both oestradiol and to oestriol. We conclude that oestriol increases gap junction communication in human myometrium by increasing gap junction expression. Elevated oestriol concentrations may thus play a role in the initiation of labour in women, by increasing cell-cell communication in the myometrium.     

Alterations in saliva steroid hormone levels after oral mifepristone administration in women with pregnancies of greater than 41 weeks' gestation

The objective of this study is to describe the effects of oral mifepristone administration on saliva levels of estradiol, estriol, progesterone, and cortisol in women with postdates pregnancy. As an adjunct to a randomized controlled trial comparing 200 mg oral mifepristone to placebo for cervical ripening and labor induction in women with pregnancies greater than 41 weeks' gestation, saliva samples were obtained before drug administration and every 6 hours thereafter for 24 hours. Estradiol, estriol, progesterone, and cortisol levels were measured by radioimmunoassay. Ninety-seven participants received mifepristone, and 83 received placebo. Saliva steroid hormone data were available for 71 mifepristone-and 60 placebo-treated women. Mean baseline saliva estradiol, estriol, progesterone, and cortisol levels were similar between study groups. At 24 hours after study medication administration, saliva estradiol, estriol, progesterone, and cortisol levels in the mifepristone group were significantly elevated compared with baseline. There was no significant change in hormone levels in the placebo group. Oral mifepristone significantly increased saliva estradiol, estriol, progesterone, and cortisol compared with placebo. This may reflect mifepristone's antiglucocorticoid properties. These hormone elevations may contribute to the mechanism by which mifepristone causes cervical ripening and increases myometrial activity.     

Increased saliva oestriol to progesterone ratio before preterm delivery: a possible predictor for preterm labor?

Saliva oestriol, oestradiol, and progesterone concentrations were measured in 23 women who went into spontaneous preterm labour. The patients fell clinically and biochemically into two groups. The 13 who went into preterm labour with intact membranes had a saliva oestriol to progesterone ratio greater than one in every case and greater than the 95th centile for their length of gestation in 12 cases; by contrast, all those who went into spontaneous preterm labour after prolonged rupture of the membranes had an oestriol to progesterone ratio less than one and below the 50th centile for their period of gestation in the one to four days before delivery. Saliva oestradiol to progesterone ratios were randomly distributed throughout the normal range in both groups. It appears that preterm labour without prior prolonged rupture of the membranes is, like term labour, preceded by an increase in the saliva oestriol to progesterone ratio. It may therefore be possible to use this ratio to predict preterm labour.     

Low saliva progesterone concentrations are associated with spontaneous early preterm labour (before 34 weeks of gestation) in women at increased risk of preterm delivery

Saliva progesterone and oestriol concentrations were determined weekly from 24 weeks of gestation in women at increased risk of preterm delivery. Samples were analysed from 28 women with spontaneous onset of labour and delivery before 37 weeks of gestation, and 64 who delivered at term. Saliva progesterone was lower in the 12 women delivering before 34 weeks than in those delivering later , between 34 and 37 weeks ( P  = 0.007) or at term ( P  = 0.009). Measurement of saliva progesterone may be of value in the prediction of early preterm labour and in determining which women might benefit from progesterone supplementation.