Serum hyaluronic acid levels during pregnancy and labor

OBJECTIVE: To study the changes in concentrations of serum hyaluronic acid in uncomplicated human pregnancies. METHODS: We determined the concentrations of serum hyaluronic acid, using a specific enzyme-linked immunosorbent assay, in 70 nonpregnant women, 250 women during their pregnancies, and 68 women at the time of parturition. Results were analyzed for statistical significance with Scheffé test for multiple comparisons. RESULTS: During pregnancy, mean (+/- standard deviation) serum hyaluronic acid levels were 11.4 +/- 4.5, 13.6 +/- 2.8, 20.6 +/- 1.5, and 46.9 +/- 7.9 ng/mL at 5-14 (n = 47), 15-26 (n = 46), 27-37 (n = 58), and 38-40 (n = 99) weeks' gestation, respectively. Pregnant women in labor (n = 68) had significantly higher levels (100.4 +/- 11.3 ng/mL) than did women at term but not in labor (P < .01). CONCLUSION: Maternal serum hyaluronic acid concentrations increase as pregnancy progresses and serum levels increase significantly at term. Hyaluronic acid may be associated with cervical ripening during parturition.     

Serum magnesium levels in pregnancy and preterm labor

Pregnancy is marked by a state of hypomagnesemia. The serum magnesium level shows no gestational dependence (mean, 1.79 +/- 0.44 mg/dl) until 33 weeks, at which point it continuously declines. Serum magnesium is not depressed further with the onset of labor at term. Patients in preterm labor have a significantly depressed serum magnesium level (mean, 1.60 +/- 0.46 mg/dl; 21 to 33 weeks; p less than 0.0005). This level was not dependent on whether the etiology for the preterm labor was premature rupture of the membranes (PROM), twin gestation, abruption, placenta previa with bleeding, or chorioamnionitis. With PROM, the serum magnesium level was not depressed prior to the initiation of preterm labor. However, observation of hypomagnesemia for this and other etiologies just prior to the initiation of preterm labor were not available. Possible mechanisms by which hypomagnesemia induces uterine irritability are explored, including inhibition of adenyl cyclase with resultant increase in cytoplasmic calcium levels. Patients with diabetes mellitus appeared to have slightly reduced serum magnesium levels, but the results were not statistically significant. Magnesium levels in patients with preeclampsia were not significantly different from controls. Hypomagnesemia (magnesium 1.4 mg/dl or less) may be a marker for true preterm labor.     

Prolactin levels during labor.

To test the hypothesis that prolactin (PRL) plays a role in the hormonal events of labor, serum PRL levels in 15 normal secundigravidas were measured on 2 occasions 10-15 days before delivery, at the onset of labor, at cervical dilatation of 5 and 10 cm, at the time of delivery, and on the first, second, and fifth days postpartum. The mean level of PRL was 163 ng/ml +/- 26 ng/ml at the onset of cervical dilatation; it typically decreased with the progress of labor, reaching a value of 140 ng/ml +/- 21 ng/ml at the time of delivery. The differences during the various stages of labor, however, were not found to be statistically significant. Postpartum values were significantly lower (P less than 0.01) on the fifth day after parturition. It is therefore unlikely that PRL is involved in or influenced by the hormonal interplay that occurs during labor.     

Analysis of alpha-amylase activity during pregnancy and labor

Analyses were applied by the authors to 278 samples of maternal serum, 106 amniotic fluid samples, and 81 samples of umbilical vein serum, since no complex study into alpha-amylase activity in the context of pregnancy and labour had been found in the literature. Rise in amylase activity in amniotic fluid, depending on length of gestation, had been one of the points made elsewhere in a publication and was confirmed by the authors' experiments (17th to 22nd weeks of pregnancy: means = 1,8 +/- 0,8 AU/1; 37th to 41st weeks of pregnancy: means = 10,3 +/- 6,0 AU/1). Somewhat relaxed relationships between amylase activity in maternal serum, on the one hand, and age of the pregnant woman as well as activity in amniotic fluid, on the other, were found to be without any clinical relevance. Additional correlations were not detected, not even those with complications in the course of pregnancy and in labour. Global measurement of amylase activity is of no importance to obstetric diagnosis.     

Phospholipase A2 levels during labor

Determinations of phospholipase A2 activity 2 hours after spontaneous start of uterine contractions in 14 women showed higher values than immediately post partum. The reason of this increase of enzyme activity inducing prostaglandin synthesis is not known yet.     

Maternal serum cytokines concentrations during normal pregnancy and labor

OBJECTIVES: The purpose of our study was to determine maternal serum concentrations of IL-8, IL-6, IFN-gamma during normal pregnancy and labor. MATERIALS AND METHODS: Maternal serum IL-8, IL-6 and IFN-gamma levels were measured by means of ELISA technique in 41 healthy pregnant women in 22-42 week gestation and 15 healthy women in labor at term. All newborns and afterbirths had no signs of infection. RESULTS: IL-8 values for pregnant women ranged from 1.98 to 35.2 pg/ml with the median value 10.24 pg/ml, and the 95th percentile 24.5 pg/ml. IL-8 values for women in labor at term ranged from 3.96 to 54.8 pg/ml with the median 10.4 pg/ml. No statistically significant changes in serum IL-8 concentration were observed during pregnancy or in labor. Serum IL-6 concentrations in pregnant women ranged from 0 to 21.7 pg/ml with the median value 0 pg/ml, and the 95th percentile 15.5 pg/ml. Serum IL-6 concentrations in women in labor at term were significantly higher (p < 0.05): ranged from 0 to 39.2 pg/ml with the median 10.1 pg/ml and 95-th percentile 33.5 pg/ml. Maternal serum IFN-gamma concentrations in pregnant women ranged from 0 to 9.8 pg/ml with the median value 3.9 pg/ml, the 95th percentile 9.2 pg/ml and didn't differ during labor at term: range from 0 to 14.5 pg/ml, median 1.9 pg/ml. CONCLUSIONS: Our data revealed that maternal serum IL-8 concentrations didn't changed during the course of pregnancy and in labor. Women in labor had significantly elevated serum IL-6 concentrations compared to those in pregnancy. We didn't observed such changes in serum IFN-gamma levels.