The plasma half-life of placental hormones

Interventions to Improve Rate of Diabetes Testing Postpartum in Women With Gestational Diabetes Mellitus

PURPOSE OF REVIEW

Gestational diabetes mellitus (GDM) is one of the most common medical complications of pregnancy. In the USA, four million women are screened annually for GDM in pregnancy in part to improve pregnancy outcomes but also because diagnosis predicts a high risk of future type 2 diabetes mellitus (T2DM). Therefore, among women with GDM, postpartum care should be focused on T2DM prevention. This review describes the current literature aimed to increase postpartum diabetes testing among women with GDM.

RECENT FINDINGS

Data suggest that proactive patient contact via a health educator, a phone call, or even postal mail is associated with higher rates of postpartum diabetes testing. There may also be utility to changing the timing of postpartum diabetes testing. Despite the widespread knowledge regarding the importance of postpartum testing for women with GDM, testing rates remain low. Alternative testing strategies and large randomized trials addressing postpartum testing are warranted.

Estrogen promotes sympathetic nerve regeneration in rat proximal urethra

OBJECTIVES

To assess whether sympathetic reinnervation of the rat proximal urethra is affected by differences in estrogen levels. Sympathetic innervation mediates tonic contraction of proximal urethral smooth muscle, thus contributing to urinary continence. Urethral innervation is particularly susceptible to damage during vaginal delivery, a time characterized by decreasing estrogen levels.

METHODS

Adult female rats were ovariectomized and implanted with pellets containing vehicle or estrogen to achieve serum levels similar to rodent pregnancy. The rats were injected intravenously with vehicle or the selective sympathetic neurotoxin 6-hydroxydopamine, which produces uniform and complete destruction of terminal sympathetic axons. At 1, 4, 12, and 25 days, tyrosine hydroxylase-immunoreactive sympathetic innervation of the proximal urethral smooth muscle was assessed quantitatively.

RESULTS

In rats with intact innervation, the proximal urethra is densely innervated, and nerve density is comparable, irrespective of estrogen status. 6-Hydroxydopamine induced marked sympathetic axon disruption by day 1 and complete denervation by 4 days after injection in the ovariectomized rats receiving vehicle or estrogen. In the vehicle-treated rats, few nerves were present at 12 days after sympathectomy, and innervation remained substantially less than normal levels at 25 days. In estrogen-treated rats, sympathetic reinnervation was twofold greater at 12 days and by 25 days was comparable to that of the controls.

CONCLUSIONS

Estrogen improves sympathetic reinnervation of the proximal urethra. Estrogen titers in individuals with urethral sympathetic nerve damage might, therefore, influence the rate and extent of urethral smooth muscle reinnervation.

Kinetics and secretion of placental growth hormone around parturition

OBJECTIVE

During pregnancy, placental growth hormone (PGH) is secreted into the maternal circulation, replacing pituitary GH. It is controversial whether PGH levels decline during vaginal birth. After placental expulsion, PGH is eliminated from the maternal blood. GH binding protein (GHBP) and body mass index (BMI) influence GH kinetics, but their impact on PGH kinetics is unknown. The present study was undertaken to define the kinetics of PGH during vaginal delivery and Caesarian section and to relate these kinetics to GHBP and BMI.

DESIGN

A short term, prospective cohort study.

METHODS

Twelve women had repeated blood samples drawn during vaginal delivery. From 26 women undergoing planned Caesarian delivery (CS) repeated blood samples were withdrawn before, during and after the CS, allowing PGH half-life determination.

RESULTS

During vaginal delivery, median PGH values did not change before expulsion of the placenta, although individual fluctuations were seen. Clearance of PGH from the maternal circulation was best described by a two-compartment model. The initial half-life of serum PGH was (mean +/- s.d.) 5.8 +/- 2.4 min, and the late half-life was (median) 87.0 min (range: 25.1-679.6 min). The late half-life was correlated to the pre-gestational BMI (r = 0.39, P = 0.047), but not to the serum GHBP concentration.

CONCLUSIONS

Serum PGH did not decrease significantly during vaginal delivery. Elimination of PGH fitted a two-compartment model, with an estimated initial half-life of 5.8 min. The late phase serum half-life of PGH was related to BMI, suggesting a role for maternal fat mass in PGH metabolism.

Clearance pattern of maternal serum pregnancy specific beta 1-glycoprotein after treatment in active and regressed tubal pregnancy

The clearance pattern of maternal serum pregnancy specific beta 1-glycoprotein (SP1) was studied in 16 cases of tubal pregnancy (9 active and 7 regressed) after 12, 24, 48, 72, 96, 120 and 192 h following surgery. The mean values of the hormone in both groups showed a statistically highly significant difference in all measurements before and after treatment (P less than 0.001), but they followed the same exponential regression pattern. The half-life of SP1 in active tubal pregnancies after salpingectomy was 36.2 h and in regressed tubal pregnancies after salpingostomy was 37.5 h.

The disappearance rate of Schwangerschaftsprotein 1 in normal and pathological pregnancies

In six women with a normal vaginal delivery at term, in 12 women who had a suction curettage between 6 and 12 weeks gestation and in eight women with an ectopic pregnancy, the post-partum or the post-surgery decline in radioimmunoassayable SP1 was faster during the first 24 h after surgery or delivery than later, so that two half-lives were calculated. The first 'half-life' of about 20 h (0-24 h after delivery or surgery) was of the same order of magnitude in all groups studied and corresponded well to previously published values. The mean second 'half-life' (greater than 24 h after delivery or surgery) was significantly longer in term (72.2 h) and in ectopic pregnancies (64.1 h) than in first trimester pregnancies (45.5 h). These results might indicate that the metabolism of SP1 either changes during pregnancy or that the changing SP1 beta/SP1 alpha ratio during pregnancy markedly influences the levels of SP1 as measured by radioimmunoassay.

Periovulatory secretion of immunoactive pregnancy-specific beta 1-glycoprotein (SP1) in humans: comparison with "normal" SP1

The pregnancy-specific beta 1-glycoprotein (SP1)-immunoreacting material in serum from two patients around ovulation was compared with serum SP1 activity derived from normal pregnant women. This was done by antibody binding experiments, density gradients and binding to lentil lectin. Periovulatory SP1 behaved similarly to SP1 from pregnant patients. It is therefore suggested that the periovulatory immunoreacting material is true SP1 and that this protein, though rarely, can be synthesized outside the trophoblast in healthy women.

Studies on the half-life of Schwangerschaftsprotein 1 (SP1)

Schwangerschaftsprotein 1 (SP1) was measured in 10 women at intervals after delivery of the placenta. SP1 alpha decreased more sharply than SP1 beta and showed evidence of a two-compartmental distribution in the mother. Trace amounts of both proteins could still be detected 5 weeks after delivery. It is concluded that the findings support the view that the two proteins are separate biological entities and that there is a possibility that SP1 beta is generated from SP1 alpha in the maternal compartment.

Placental protein 5: disappearance from the circulation after delivery

Blood was collected from 8 women following delivery at term. The decline in serum concentrations of placental protein 5 following the delivery of the infant's head was studied for 12 h. Placental protein 5 levels fell very rapidly with a half-life of 5-39 min. In the majority of women placental protein 5 was undetectable after 12 h (i.e. less than 2 microgram/l).

Late third trimester unconjugated serum oestriol levels in normal and hypertensive pregnancy: relation to birth weight

In 100 normal singleton pregnancies and in 44 patients with pregnancy hypertension (pre-eclampsia) linear regression analyses demonstrated highly significant positive correlations between birth weights and late third trimester maternal serum unconjugated oestriol (O3) levels. Correlation coefficients increased, though not significantly, after standardising birth weights according to maternal size, parity and sex of infant. Pregnancy hypertension was classified according to the duration of clinical signs. In 23 patients with short duration pregnancy hypertension (onset 14 days or less before delivery) neither maternal age nor birth weight differed from normal controls. Mid-pregnancy weights were greater and unconjugated O3 levels lower and only one infant was growth retarded. Twenty one patients with long duration pregnancy hypertension (onset more than 14 days before delivery) were found on average to be heavier at mid-pregnancy and older than those in whom the condition was short-lived. Unconjugated O3 levels in patients with long duration hypertension were significantly below those in the short duration group. One third of infants born following long duration hypertension were growth retarded.

Oxytocinase versus estriol for the assessment of fetal well-being

In a group of 26 primiparae, 48 hours after cesarean section, we have examined the urinary estriol (E3) and serum cystine aminopeptidase (CAP). 13 patients received ampicillin treatment, and 13 patients did not. In the group of patients without antibiotic treatment the urinary estriol after 48 h reached an average value of 5.55 mg/24 h. in the group of treated patients the drastic decrease of E3 reached a mean value of 1.62 mg/24 h. This fact may be explained by the arrest of the feto-placental inflow after delivery, and the blocking effect of the antibiotic on the enterohepatic circulation, compartment which afford for 50% of the maternal circulating estrogen. From the present work it results that the determination of the serum CAP activity, which is not affected by antibiotic treatment, is an appropriate test for the assessment of the fetoplacental unit activity. It must be mentioned that all the biochemical tests complete one another and may have a decisive role in taking immediate obstetrical decisions, together with the additional fetal heart rate monitoring and oxytocin challenge test.

Interrelationships of human chorionic gonadotropin, human placental lactogen, and pregnancy-specific beta 1-glycoprotein throughout normal human gestation

Human chorionic gonadotropin (hCG), human placental lactogen (hPL), and pregnancy-specific beta 1-glycoprotein (PSBG) were measured by radioimmunoassay in 270 samples of serum from women with uncomplicated pregnancies. All three proteins were significantly correlated with each other in individual samples of serum and with the estimated trophoblastic mass during the first trimester. No significant correlation could be demonstrated between the concentrations of hCG and PSBG in maternal serum during the second or third trimesters or between the concentrations of hCG and hPL during the second trimester. Levels of PSBG and hPL in serum were significantly correlated throughout all three trimesters. These findings suggest that the secretion of hCG, hPL, and PSBG may be regulated by similar control mechanisms during the first trimester of pregnancy. However, after this period, the factors that modulate the production of hCG differ from those that regulate the production of hPL and PSBG.

Maternal hormone profile in oxytocin induced labour

Serial blood samples were collected from ten patients at between 40 and 42 weeks gestation, who were having labour induced by amniotomy and intravenous oxytocin. The plasma levels of human placental lactogen and pregnancy-specific beta 1 glycoprotein showed no more than their normal late pregnancy variability during labour; oestradiol-17 beta showed a small rise in early labour followed by a fall in the second stage of labour; unconjugated oestriol and 11-hydroxycorticosteroids showed a progressive rise throughout labour and progesterone a progressive fall. The ratio of progesterone to oestradiol-17 beta fell throughout labour. The significance of these changes in our understanding of the control of placental hormone secretion and of the hormone profile of spontaneous labour is discussed.

Disappearance of pregnancy-specific beta 1 glycoprotein from the maternal circulation after delivery

It is likely that there are systematic differences between circulating pregnancy-specific beta 1 glycoprotein (SP1) levels measured by radioimmunoassay and immunoprecipitation systems. We have re-investigated the decline in circulating levels of SP1 following delivery of the placenta. Serial blood samples were collected for 120 hours from 10 women following Caesarean section or vaginal delivery at term. The apparent half-life of SP1 after delivery ranged between 17 and 45 hours.

Measurement of serum levels of oestriol and human placental lactogen in the management of pre-eclamptic pregnancies

Maternal serum levels of total oestriol and human placental lactogen (HPL) were measured in 280 normal and 87 pre-eclamptic pregnancies. Normal levels of HPL, but significantly reduced total oestriol values were obtained when pre-eclampsia was present. However, when fetal complications developed, both hormone levels were further significantly reduced. The severity of pre-eclampsia had no effect on the serum levels of oestriol and HPL. An analysis of the 18 pregnancies with significant fetal-placental dysfunction showed that 13 (72%) were predicted by unfavourable levels of total oestriol, nine (50%) by unfavourable levels of HPL, and 14 (78%) by the use of both assays. The present study supports the value of antenatal measurement both of serum total oestriol and of HPL in the management of pre-eclamptic pregnancies.

Enterohepatic circulation of oestriol: a study of the effects of ampicillin on plasma oestriol levels

Plasma total oestriol was measured daily before and during ampicillin therapy in five pregnancy patients and in eight patients, four of whom were receiving ampicillin, for four days following delivery. Ampicillin caused a fall in plasma oestriol of 25 per cent during the first three days of treatment, thereafter the level remained stable with a lower day-to-day variability than in untreated patients. Ampicillin reduced the plasma half life of total oestriol by 60 per cent. This study illustrates how the re-entry of oestriol from the gut leads to irregular fluctuations in plasma oestriol levels and helps to keep up the plasma concentration of the steroid when inflow from the fetoplacental unit is cut off.