The correlation between fetal bradycardia area in the second stage of labor and acidemia at birth.

OBJECTIVE: To quantify fetal bradycardia in the second stage of labor and to determine the threshold of the area that correlates with neonatal acidemia. METHOD: We analyzed the cardiotocograms of 33 women with single pregnancy and term spontaneous labor who presented fetal bradycardia in the second stage of labor. We retrospectively calculated the fetal bradycardia area in the last 60 min before delivery with an upper limit of 90 bpm and correlated the area with neonatal pH. The study of the regression line determined the cut-off threshold between fetal well-being and distress. Significance was set at p < 0.05. RESULTS: The linear correlation between the bradycardia area and neonatal pH indicate that increasing bradycardia area was correlated with significant pH decrease. The threshold value of the area indicative of severe acidemia was ≥ 12.72 cm(2) (Pearson r = -0.76, p < 0.002). The diagnostic accuracy of the test was 73%. The PPV = 78.5% and the NPV = 68.4%. With such a cut-off, the timing of acidemia can be calculated as 25 min for a fetal heart rate (FHR) of 80 bpm, 13 min for a FHR of 70 bpm, 8 min for a FHR of 60 bpm, 6 min for a FHR of 50 bpm and 5 min for a FHR of 40 bpm. CONCLUSION: The bradycardia area in the second stage of labor significantly correlates with an accurate timing of fetal acidemia. Regardless of the cause of the bradycardia, the time for intervention is often short, meaning that any available intervention may be ineffective in preventing acidemia or even injury.

beta-Endorphin concentration in colostrums of Burkinabe and Sicilian women.

OBJECTIVE: Endorphins (EPs) present in human colostrum may be relevant for immediate postnatal fetal adaptation because this compound is involved in stress response and adaptation mechanisms. Endorphin levels in human colostrum are two-fold greater than corresponding maternal plasma levels; however, the high endorphin levels in human milk decrease as lactation continues. The aim of this study was to determine the beta-EP concentration in colostrums of women residing in Burkina Faso and Sicily. In addition, we investigated the source of potential differences in beta-EP levels between these populations, especially ethnic sources of these deviations. METHODS: The concentration of beta-EP was determined in the colostrum from the first 3 d subsequent to delivery by an enzyme immunoassay as immunoreactive material (IRM). RESULTS: The production of beta-EP in the colostrum was significantly higher in Burkinabe mothers (0.83 +/- 0.04 ng/mL) than in Sicilian mothers (0.31 +/- 0.02 ng/mL) at 24 h after delivery. Colostrum levels of beta-EP declined progressively during the first 3 d after delivery in both populations (0.64 +/- 0.1 and 0.28 +/- 0.015 ng/mL, respectively, at 72 h). The level of beta-EP-IRM correlated significantly with pain and psychological involvement during and after delivery. In addition, the correlation between beta-EP-IRM and length of stage II of labor was significant (P < 0.0001) in the colostrums of Sicilian mothers who received ergot derivatives, episiorrhaphy, and child birth preparation. The correlation between beta-EP-IRM and length of stage II was less significant (P < 0.001) in the colostrums of Burkinabe mothers who received neither ergot derivatives nor child birth preparation. CONCLUSION: During the first 3 d after labor the beta-EP-IRM concentration in the colostrums of Burkinabe mothers differs from that of Sicilians. In addition, because Burkinabe women produce a larger volume of colostrum, their newborns receive, during the first days of life, a larger absolute amount of beta-EP-IRM, likely resulting in better postnatal fetal adaptation.

Oxytocin secretion and human parturition: pulse frequency and duration increase during spontaneous labor in women.

The secretory pattern of oxytocin was determined in blood samples taken at 1-minute intervals for 30 minutes from 32 parturient women. The samples were collected in a manner that minimized degradation by plasma oxytocinase, and a highly specific antibody was used for the radioimmunoassay. The results indicated that oxytocin is secreted in discrete pulses of short duration. The frequency of the pulses was significantly higher during spontaneous labor than before the onset of labor. The mean pulse frequencies per 30 minutes were 1.2 +/- 0.54 before labor, 4.2 +/- 0.45 during the first stage, and 6.7 +/- 0.49 during the second and third stages of labor. The mean pulse durations in these three groups were 1.2 +/- 0.20, 1.9 +/- 0.28, and 2.0 +/- 0.26 minutes, respectively. The amplitude of the pulses was variable with no significant differences between the groups, the majority being around 1.0 microU/ml. The spontaneous pulses were of similar magnitude as those measured in 18 women after intravenous injections of 4 to 16 mU of oxytocin, which doses stimulated uterine contractions. We therefore conclude that the pulses of oxytocin observed at increasing frequency during spontaneous labor are of physiologic significance and provide evidence for the participation of oxytocin in the onset and maintenance of spontaneous labor.

Increased maternal plasma concentration of endothelin-1 during labor pain or on delivery and the existence of a large amount of endothelin-1 in amniotic fluid.

The concentration of endothelin-1 (ET-1) in plasma and amniotic fluid from normal pregnant women was determined by a sensitive sandwich-enzyme immunoassay system, established recently. The plasma ET-1 level increased gradually during normal pregnancy as the pregnancy advanced, the levels (0.40 +/- 0.02 pmol/l, n = 45) being significantly (p less than 0.05) higher after 29 weeks of gestation than those (0.32 +/- 0.01 pmol/l, n = 30) before 28 weeks of gestation. The plasma ET-1 level during labor pain was significantly higher (0.59 +/- 0.06 pmol/l, n = 10) than that (0.40 +/- 0.02 pmol/l, n = 45) in the 3rd trimester of pregnancy without labor pain (p less than 0.02). Moreover, a high level of ET-1 (17.38 +/- 0.25 pmol/l, n = 18) was detected in amniotic fluid on term delivery. The ET-1 level in amniotic fluid was significantly higher than the levels in maternal and umbilical cord plasma (p less than 0.001 and p less than 0.001, respectively). After delivery the maternal ET-1 level decreased gradually and 2 day postpartum ET-1 levels reached the normal non-pregnant level.

Correlation between levels of plasma adenosine triphosphate and stress to the fetus at delivery.

Adenosine triphosphate (ATP) and its metabolites are released from intracellular stores and levels of ATP in the plasma are affected by hypoxia and by exercise. We examined levels of plasma ATP in the fetus at the time of obstetrical delivery. The arterial (ACB), venous cord (VCB) and maternal venous blood (MVB) samples were collected immediately after clamping of the cord. ATP was determined by the bioluminescence method. The levels of plasma ATP were significantly higher in ACB than in VCB or in MVB. There were significant correlations between the levels of ATP in ACB and in VCB, between the levels in ACB and in MVB and between the levels in MVB and in VCB. In case of delivery by elective cesarean section, the levels of ATP in ACB were significantly higher than those in ACB of the fetus delivered vaginally. We found a significant correlation between the levels of plasma ATP in ACB and PO2 in VCB, though there was no significant correlation between the levels of ATP and pH and PCO2. These observations suggest that ATP in ACB may be of fetal origin, that the levels decrease concomitantly in response to stress during vaginal delivery and correlate with the oxygen supplied from the placenta.