Maternal and fetal plasma cortisol levels at parturition.

Fetal adrenal function during pregnancy has a probable role in parturition. Ninety-five mothers and fetuses were evaluated to ascertain maternal or fetal plasma cortisol interrelationships under various clinical situations. When mode of delivery was evaluated, maternal cortisol levels showed no differences. However, the fetuses from vaginal delivery (mean, 43.7 mug/100 ml) had higher levels than those from cesarean section (mean, 34.7 mug/100 ml). Induction of labor showed a rise in maternal cortisol from preinduction levels (mean, 40.2 mug/100 ml) to delivery (mean, 49.6 mug/100 ml), probably reflecting the maternal stress of labor. The fetal cortisol level after induced labor (mean, 35.2 mug/ml) supporting the adrenal contribution to the initiation of labor. Gestational age of the fetus was significant in the fetal cortisol levels: 36 weeks or less (mean, 34.1 mug/100 ml); 37 weeks or more (mean, 44.5 mug/100 ml). This again supports the development of adrenal maturity. Fetal weight, postdatism, acute and chronic fetal distress, hypertensive disease in pregnancy, and race were evaluated without revealing any significant intergroup differences. Two anencephalic pregnancies were also studied.     

Unbound cortisol in umbilical cord plasma and maternal plasma: a reinvestigation

Unbound cortisol was assayed in maternal and cord plasma. A method was used in which experimental conditions are carefully selected to approach as closely as possible the in vivo situation.¹ In maternal plasma at term, the proportion of unbound cortisol (9.7 ± 1.5%) (mean ± SE) was identical to that of normal nonpregnant women (9.7 ± 0.4%). However, the concentration of unbound cortisol was 3-fold higher at term (46.0 ± 5.9 ng/ml) than that in nonpregnant women (14.2 ± 1.0 ng/ml). During labor an increase was observed, and at birth the proportion (and concentration) of unbound cortisol was extremely high varying between 17.0 ± 0.8% (92.3 ± 7.4 ng/ml) and 20.9 ± 1.4% (130.4 ± 17.9 ng/ml) (spontaneous and induced vaginal deliveries, respectively). In cord plasma at term and before labor (fetuses delivered by elective cesarean section), the proportion of unbound cortisol was high (29.1 ± 1.3 %) but its concentration (9.6 ± 1.1 ng/ml) was only slightly lower than that observed in normal adults. Labor had an important stimulatory effect as observed in cases of vaginal delivery after spontaneous labor (proportion of unbound cortisol 35.1 ± 1.2%, concentration of unbound cortisol 15.4 ± 1.35 ng/ml, respectively). No difference was observed between spontaneous and provoked labor since similarly high values of unbound cortisol were found in cord plasma after oxytocin-induced labor followed by vaginal delivery (36.2 ± 1.4% and 23.0 ± 5.2 ng/ml).     

Elevated levels of maternal plasma alpha-fetoprotein after amniocentesis.

An elevation of maternal AFP levels was observed in 11 of 65 cases (17 per cent) after amniocentesis. It is suggested that blood samples in which AFP levels are to be measured should always be collected before and not after amniocentesis.     

Fibrinopeptide A levels in maternal and newborn plasma

Plasma fibrinopeptide A (FPA), a dynamic measure of intravascular coagulation, was determined in 70 healthy Chinese women during normal pregnancy, labour, delivery and the early puerperium and compared to a group of healthy non-pregnant adult controls. In the normal controls the plasma FPA level (mean ± SD) was 1.43 ± 0.46 ng/ml. During pregnancy and labour, the FPA levels were 3.05 ± 0.98 ng/ml and 11.47 ± 4.43 ng/ml, respectively, and it reached a peak of 32.95 ± 11.66 ng/ml at parturition, then falling to 6.15 ± 2.52 ng/ml in the early puerperium. All these levels were significantly higher (p < 0.001) compared to controls. Fifteen of the 21 mothers with blood sampling during parturition also had umbilical cord blood taken for determination of FPA level. There was no significant difference between the maternal (34.07 ± 10.12 ng/ml) and cord (31.06 ± 12.67 ng/ml) plasma FPA levels. It is concluded that the hypercoagulable state in women during pregnancy and the puerperium is associated with increased intravascular coagulation activity, and that increased intravascular coagulation activity also occurs in the fetus during parturition. This observation may account for the increased risk of thrombotic disorders observed in pregnant and parturient women as well as in the newborn.     

The effect of labour on ACTH and cortisol levels in amniotic fluid and maternal blood.

Levels of adrenocorticotrophic hormone (ACTH) and cortisol were measured in amniotic fluid during labour and in maternal blood during and after labour. There was a significant rise of maternal ACTH and cortisol levels during labour and a significant decrease after delivery in all 14 patients studied. There were no significant changes in amniotic fluid ACTH and cortisol levels during labour. The initial level of ACTH in amniotic fluid (162-7 pg/ml) was higher than that in maternal circulation (120-2 pg/ml). The correlation between maternal and amniotic fluid ACTH was not significant while the corresponding correlation for cortisol values was.     

Effect of stress during labor on the concentration of cortisol and estriol in maternal plasma.

The effect of stress during labor on the plasma concentration of cortisol, unconjugated estriol, and human chorionic somatomammotropin was studied in 15 healthy primiparous women. According to the method of pain relief the parturients were divided into two groups. One group was given continuous epidural analgesia and the other group received pethidine, diazepam, and nitrous oxide/oxygen in response to pain. In the most stressed nonepidural group there was a significant rise in the cortisol level during labor and the estriol concentration fell significantly. In the epidural group no significant changes were observed with respect to the concentration of either cortisol or estriol. These results give further support to the hypothesis that severe maternal stress may lead to a reduced concentration of estriol in maternal plasma.     

The relationship between maternal plasma prolactin and cortisol concentration during labor

Maternal prolactin (PRL) and cortisol levels were measured during induced labor and 30 min following delivery in 30 normal subjects between 38 and 41 wk of gestation. A significant decline in PRL levels was accompanied by a marked rise in cortisol levels, suggesting a paradoxal suppression of PRL due to stress of labor.     

Diurnal variations in unconjugated oestriol levels during early pregnancy and their relation to maternal cortisol levels

Summary We studied maternal plasma levels of oestriol (measured by radioimmunoassay) and total cortisol (measured by a protein binding method) in 11 women from 8 to 22 weeks gestation. Blood specimens (5 ml) were drawn over a 24-h period at 60 and 30 min intervals. The diurnal rhythm of cortisol with higher values in the morning than in the afternoon and evening was present at all gestational ages studied. Unconjugated plasma oestriol showed a similar circadian rhythm to maternal cortisol (r=0.576,P<0.01) in the 8th week. From the 9th to the 11th week oestriol values rose and there was no evidence of a circadian rhythm. In the 12th week plama oestriol again showed a circadian rhythm, with higher values at night (117.3±9.5 pg/ml) than during day-time (104±7.5 pg/ml,P<0.001). This pattern remained until the 22nd week, when plasma oestriol levels at night (3.78±0.49 ng/ml) were markedly higher than in the day-time (3.16±0.3 ng/ml,P<0.001). An inverse relation between oestriol and cortisol levels as shown in late human pregnancy could not be demonstrated for the early stages we studied. The interval between rising cortisol and faling oestriol levels decreased from 6 h in the 12th week to 3.5 h in the 22nd week of gestation. This suggests an increasing sensitivity of the fetal hypothalamus to the feedback effect of maternal cortisol.     

Elevated maternal plasma corticotropin-releasing hormone levels in pregnancies complicated by preterm labor.

OBJECTIVES: We investigated whether maternal plasma levels of the placental hormone corticotropin-releasing hormone are elevated in pregnancies complicated by preterm labor. STUDY DESIGN: Mean maternal corticotropin-releasing hormone levels were studied in women who met specific criteria for preterm labor and in women with normal pregnancies. Levels were also compared in the latent and active phases during term labor. RESULTS: In pregnancies complicated by preterm labor, maternal corticotropin-releasing hormone levels were higher than in normal pregnancies; this elevation occurred before labor was diagnosed clinically (p less than 0.05). When preterm labor was associated with infection, the mean levels were not elevated. Mean plasma levels were similar in latent and active phases during labor at term. CONCLUSION: Maternal plasma corticotropin-releasing hormone levels are elevated in association with preterm labor. This elevation does not appear to be due to labor itself and may reflect an early activation of the placenta before the onset of preterm labor.     

Elevated maternal plasma corticotropin releasing hormone levels in twin gestation

The placenta secretes large amounts of the hypothelamic hormone, corticotropin releasing hormone (CRH) into the maternal and fetal circulation during pregnancy. We and other investigators have shown that during normal pregnancy, maternal plasma CRH levels begin to rise in the second trimester with a dramatic increase in CRH levels during the 5-6 weeks preceding the onset of labor. This rise in maternal plasma CRH is parallel to the rise of placental CRH mRNA which has been reported to occur with gestational maturation. Mechanisms underlying the control of CRH secretion by the placenta have not yet been determined. In twin gestation, increased fetal-placental mass has been shown to be associated with elevated maternal levels of several placental hormones as compared to singleton gestation. We measured maternal plasma CRH in both twin and singleton gestation to investigate whether the larger size of the fetal-placental unit in twin gestation is associated with elevated maternal CRH levels. Seventy-six serial venous blood samples were collected from 20 women with twin gestation and 40 samples were obtained from 27 women with uncomplicated singleton gestation. Gestational age was determined by history of a known last menstrual period and first trimester clinical examination and confirmed by ultrasound examination. CRH was extracted from 1-2 ml plasma with SEP-Pak C18 cartridges and eluted with triethylamine-formic-acid propranolol. CRH was measured by radioimmunoassay (RIA) with human CRH standard and antiserum to human CRH raised in our laboratory. Mean CRH levels were calculated for four week intervals. In both singleton and twin gestation, the maternal plasma CRH levels increased with advancing gestational age. After 29 weeks of gestation, maternal plasma CRH levels in twin gestation were significantly higher than those in singleton gestation (p less than 0.01). At 37 to 40 weeks of gestation, mean maternal CRH was 1167 +/- 237 pg/ml in singleton gestation as compared to 6927 +/- 1725 pg/ml in twin gestation (p less than 0.05). In addition, the rapid rise in plasma CRH levels which occurs near term in singleton gestation, occurred earlier in twin gestation. This early rise in maternal CRH levels persisted when the data from twin pregnancies complicated by preterm labor were removed from the analysis.(ABSTRACT TRUNCATED AT 250 WORDS)     

A longitudinal study of the changes in lymphocyte populations and their relationship to plasma cortisol levels in the perinatal sow

The total leucocyte count and proportion of lymphocytes, B lymphocytes and IgM-bearing (μ) lymphocytes and plasma cortisol were measured in 6 sows over the peripartum period. From these measurements the total lymphocyte, B and μ lymphocyte and non-μ lymphocyte counts were calculated. There was a significant rise in cortisol on day ? 1, 0 and 1 relative to parturition and a significant fall in the proportion and absolute count of the lymphocytes on days 0 and 1. There was a significant correlation between both the proportion (P < 0.02, r = ?0.39) and number (P < 0.02, r = ?0.37) of lymphocytes and plasma cortisol. The changes in sow leucocytes over the peripartum period were related to changes in plasma cortisol rather than to parturition. Furthermore, there was no significant change in either the proportion of B and μ lymphocytes or the minor immunoglobulin-bearing subpopulations over the peripartum period.     

Effects of betamethasone on plasma levels of estriol, cortisol and HCS in late pregnancy.

The effect of a single dose of betamethasone on the maternal plasma concentration of estriol and cortisol was studied. The concentration of estriol decreased rapidly. A maximal suppression of about 70 per cent was seen after 6-24 hours. A similar influence on the maternal plasma concentration of cortisol was observed. HCS (human chorionic somatomammotropin) was not influenced by betamethasone. These facts have to be taken into consideration after treatment with synthetic corticosteroids in high risk pregnancies.     

Testosterone levels in midtrimester maternal and fetal plasma and amniotic fluid

Testosterone was measured in maternal plasma (58 samples), amniotic fluid (71 samples) and fetal plasma (55 samples) in 79 patients between 15 and 23 weeks' gestation. Maternal plasma testosterone levels were unrelated to fetal sex. Amniotic fluid testosterone was significantly higher in male than female fetuses but did not reliably predict fetal sex. A correct diagnosis of fetal sex was made by testosterone assay of pure fetal plasma in 39 out of 40 males and in 15 out of 15 females using 1.70 nmol/l as the cut-off value. This investigation is not the method of choice for routine fetal sexing but may be of value in fetuses suspected of having certain endocrine disorders.     

ACTH levels in maternal, fetal and neonatal plasma after short-term prenatal dexamethasone therapy.

The effect of prenatal dexamethasone therapy (12, 8 and 4 mg doses given intramuscularly on three consecutive days) on ACTH levels in maternal plasma (n=33), mixed umbilical cord plasma (n=31) and plasma from the newborn (n=29) was studied, and the results were compared with those obtained in 56 healthy parturients and 50 of their newborn. Maternal ACTH after delivery was significantly lower in the mothers treated with dexamethasone than in the control group. Cord ACTH values were similar in the two groups. ACTH levels fell during the early neonatal period, but only at 12 to 24 hours were the ACTH levels significantly lower in the dexamethasone group than in the controls. Gestational age, birth weight and the interval between the dexamethasone therapy and delivery had no significant effect on cord ACTH levels. Short-term prenatal dexamethasone therapy seemed to have very little effect on ACTH secretion in the mother, in the fetus and in the newborn.     

The effect of isoxsuprine treatment of estrogen levels in maternal and umbilical cord plasma.

Estrogen concentrations in maternal plasma were determined in ten apparently normal patients attending clinic in the last trimester of pregnancy before, during, and after a maximum of four weeks isoxsuprine treatment. Eleven control patients were also studied at similar times of pregnancy. Isoxsuprine treatment appeared to have no specific effect on the levels of either estradiol alone or on total estrogens with all patients studied showing some increase in the concentrations of these estrogens as the pregnancies approached term. In four other patients treated with isoxsuprine for pregnancy complications, changes in plasma total estrogen concentrations during treatment were variable and did not correlate with the amount administered. The levels of estradiol in umbilical cord plasma from 17 isoxsuprine-treated pregnancies were similar to those observed in 24 non-treated pregnancies.