Objective
The amniotic cavity is normally sterile for bacteria. However,
experimental evidence indicates that regular uterine contractions exert a
suction-like effect whereby vaginal fluid ascends into the uterine cavity
with contractions (demonstrated by sonohysterography contrast media).
Consequently, this study was conducted to determine whether the presence and
progress of labor are associated with an increased risk of microbial
invasion of the amniotic cavity (MIAC), intraamniotic inflammation, and
histologic chorioamnionitis in women with term pregnancies with intact
membranes.
Study Design
Amniotic fluid (AF) was obtained from term singleton pregnant women
with intact membranes at the time of cesarean delivery. AF was cultured for
aerobic and anaerobic bacteria and genital mycoplasma, and
white blood cell (WBC) count was determined. Patients were divided into 3
groups according to the presence or absence of labor and the progress of
labor. Nonparametric statistics were used for analysis.
Results
Results included: (1) a total of 884 pregnant women were enrolled and
divided into 3 groups: group 1, not in labor (n = 775);
group 2, in early labor (cervical dilatation less than 3 cm)
(n = 86); and group 3, in active labor (Cervical
dilatation 4 cm or greater) (n = 23); (2) the frequency of
MIAC was 1% (6 of 775) in women not in labor, 3.5% (3 of 86)
in patients with early labor, and 13% (3 of 23) in patients with
active labor; and (3) the median AF WBC count and the frequency of
histologic chorioamnionitis were also higher in the presence of labor than
in the absence of labor.
Conclusion
We came to the following conclusions: (1) labor is associated with an
increased risk of MIAC, a higher median AF WBC count, and histologic
chorioamnionitis in term pregnancy with intact membranes; (2) the more
advanced the cervical dilatation, the greater the risk of MIAC, a higher
median AF WBC count, and histologic chorioamnionitis; and (3) in contrast,
fetal inflammation (funisitis) did not increase with the presence of labor
or as a function of cervical dilatation. We propose that labor predisposes
to MIAC, a higher median AF WBC count, and histologic chorioamnionitis.
Objectives. The role of prostaglandins (PGs) in the onset of human parturition has been controversial. Specifically, some investigators have proposed that PGs are the consequence rather than the cause of labor. An important question is whether or not amniotic fluid (AF) PG concentrations increase before the onset of labor in humans. Methods. The concentrations of PGs were determined in AF obtained from 167 singleton pregnant women with intact membranes. Patients were divided into four groups: (1) preterm not in labor (gestational age 15-36 weeks, n ¼ 65); (2) term not in labor (n ¼ 68); (3) spontaneous labor at term with cervical dilatation 54 cm (n ¼ 25); (4) spontaneous labor at term with cervical dilatation 4 cm (n ¼ 9). AF was obtained by transabdominal amniocentesis or collected at the time of cesarean delivery. All patients met the following criteria: (1) normal pregnancy outcome; (2) clear AF; (3) no significant medical or obstetric complications such as diabetes mellitus, preeclampsia, preterm birth, fetal growth restriction, or major congenital malformations; and (4) no significant neonatal complications. The concentrations of PGE2 and PGF2a in AF were determined by enzyme-linked immunosorbent assay (ELISA). Non-parametric analysis was performed. Results. (1) AF PG concentrations remained unchanged with advancing gestation until 36 weeks of gestation; (2) however, an abrupt increase in AF PG concentrations was observed before the onset of labor at term; (3) among cases without labor at term, the median AF PGF2a concentration increased with advancing gestation; (4) the presence of labor and the degree of cervical dilatation were significantly associated with a higher concentration of PGF2a.Conclusions. An abrupt increase in AF PG concentrations (25-fold for PGF2a) occurs before the onset of spontaneous labor at term in humans; these observations suggest that PGs increase prior to the onset of labor and contradict the claim that an increase in PG concentrations is the consequence of labor.
Objectives: The onset of preterm labor has been proposed to have survival value and to be adaptive in nature. This hypothesis would predict that induced preterm birth may be associated with higher rates of complications than spontaneous preterm birth. The purpose of this study was to determine if there is a difference in the frequency of neonatal respiratory distress syndrome (RDS), the most common neonatal complication, according to the etiology of preterm birth (e.g., preterm labor wPTLx, preterm PROM, or pregnancies which ended because of maternal-fetal indications).
Study design:The relationship between the occurrence of RDS and the obstetrical circumstances leading to preterm birth was examined in 257 consecutive singleton preterm births (gestational age: 24-32 weeks). Cases with major congenital anomalies were excluded. The study population was divided into two groups according to the cause of preterm birth: 1) preterm birth due to PTL with intact membranes or preterm PROM (spontaneous preterm birth group); and 2) preterm birth due to maternal or fetal indications (indicated preterm birth group). Results: 1) RDS was diagnosed in 47% of cases; 2) RDS was more common in patients with indicated preterm birth than in those with spontaneous preterm birth group (58.1% vs. 38.4%, Ps0.002); 3) Patients with indicated preterm birth had a significantly higher mean gestational age at birth, but lower mean birth weight, lower rate of histological chorioamnionitis and higher rates of cesarean delivery, 5 min Apgar score of -7, and umbilical arterial blood pH of -7.15 than those with spontaneous preterm birth (P-0.05 for each); 4) Antenatal corticosteroids were used in 73.4% of cases with indicated preterm birth and in 76.9% of those with spontaneous preterm birth; 5) Multivariate analysis demonstrated that indicated preterm birth was associated with an increased risk of RDS after adjusting for confounding variables (ORs2.29, 95% CI 1.22-4.29). Conclusions: 1) The rate of RDS is greater following ''indicated'' rather than spontaneous preterm birth; 2) This observation supports the view that spontaneous preterm labor is adaptive in nature.
Conclusions: Fetal lung volume can be measured using MRI with moderate accuracy both from coronal and transverse sections. MRI and B-scan ultrasound are useful tools to monitor and quantify TO stimulated fetal lung growth in sheep fetuses.
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