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PubMed1992

Maturation of antroduodenal motor activity in preterm and term infants.

Previous studies have shown that duodenal motility patterns differ in preterm and term infants, but antral motor activities were not compared. Using a validated, low-compliance, continuous-perfusion, neonatal manometric system, antral and duodenal motility was studied in 19 preterm and nine term infants. Antral motility consisted of isolated single contractions and clustered phasic contractions in term and preterm infants. There were no differences in the occurrence or amplitude of antral activity between the two groups of infants. Thus, there was no change of antral motor activity with advancing gestational age. As has been shown in other previous studies, however, intestinal motor characteristics were more immature in preterm than term infants; clustered phasic contractions occurred more frequently (P less than 0.02) and were of shorter duration (P less than 0.02) and lower amplitude (P less than 0.005). Duodenal clusters were significantly less common, while their amplitudes were significantly increased with increasing gestational age. The proportion of antral clusters that were temporally associated with duodenal activity was significantly lower in preterm infants than in term infants (P less than 0.001). Moreover, the degree of association of antral and duodenal activity increased significantly with gestational age (r = 0.5, P = 0.006). These data show that fasting antral motor activity per se is comparable in preterm and term infants; they also suggest that the temporal association of antral and duodenal activity develops in association with progressive changes in duodenal motor activity in the preterm infant.

Duodenum↗

PubMed1997

Chorioamnionitis caused by gram-negative bacteria as an etiologic factor in preterm birth.

The role and microbiological causes of infection and inflammation of the chorioamnion were studied in 85 patients with spontaneous preterm deliveries (< 37 weeks) and in 85 control patients with full term deliveries. Microorganisms were isolated from the freshly separated chorioamnion in 55% of preterm and 26% of term deliveries (p < 0.001). Isolation rates of gram-negative enteric bacteria were significantly higher in preterm deliveries than in term deliveries (p < 0.001), whereas differences in the isolation of other bacterial species were not significant. Histological chorioamnionitis was noted in 49% of preterm and 14% of term deliveries (p < 0.001), and was strongly associated with a positive chorioamniotic culture in both groups (p < 0.001). Histological chorioamnionitis was noted in 94%, 54%, and 4% of membranes with gram-negative rods, other microbial species and negative cultures, respectively (p < 0.001). Preterm deliveries were also associated with significantly higher rates of bacterial vaginosis (38% vs. 14%) and isolation of vaginal pathogens (85% vs. 65%). In the case of the majority (88%) of chorioamniotic isolates the same species was isolated in the vagina. The findings suggest that gram-negative enteric rods are important placental pathogens responsible for sub-clinical chorioamnionitis and possibly preterm birth. The findings support the concept that microorganisms ascending from the lower genital tract produce local inflammation, which may result in preterm labour and delivery.

Amnion↗

PubMed1996

Maternal plasma and amniotic fluid dehydroepiandrosterone-sulfate concentrations in preterm labor and delivery.

The purpose of this study was to determine whether preterm parturition is associated with changes in maternal plasma and amniotic fluid dehydroepian-drosterone-sulfate concentrations. A cross sectional study was constructed according to the gestational age at admission and response to tocolysis. Group 1 consisted of women admitted with preterm labor and intact membranes between 28 and 31 weeks and 6 days gestational age (n = 40). Group 2 included 40 patients with preterm labor between 32 and 36 weeks gestational age. Both groups were classified into two subgroups: preterm delivery within seven days of admission and term delivery. Commercially available immunoassay kits validated for amniotic fluid analysis of DHEA-S, were used to measure maternal plasma and amniotic fluid DHEA-S concentrations. Maternal plasma DHEA-S concentrations were significantly higher in women with preterm labor who delivered preterm than in those who delivered at term. (Group 1: median 800 ng/ml [range 100-1100] vs. median 200 ng/ml [70-800], P < 0.001; Group 2: median 850 ng/ml [300-1700] vs. median 300 ng/ml [90-1100], P < 0.001). In contrast, no significant differences were detected in amniotic fluid DHEA-S concentrations. Our data suggest that the rise in maternal plasma DHEA-S concentrations observed in patients with preterm labor may be related to the effects of stress during labor.

Adult↗

PubMed2002

Growth, developmental milestones and health problems in the first 2 years in very preterm infants compared with term infants: a population based study.

UNLABELLED: The outcome of very preterm infants varies widely from centre to centre and from country to country. The aim of this study was to evaluate growth, developmental milestones and post-discharge morbidity of infants born before 32 weeks of gestation in Switzerland. A questionnaire was sent to the parents of 456 survivors born in 1996. A total of 309 (68%) parents responded and their infants were matched with 309 control infants born at term. At the corrected age of 24 months, the very preterm infants had significantly lower weight (-1.0 z-scores), lower length (-1.23 z-scores), and lower head circumference (-.64 z-scores). Very preterm infants were reported to eat with a spoon later than those born at term (50% at 7.5 months corrected for prematurity versus 10 months. P<0.001), to drink later out of a cup (50% at 16.5 months versus 13.5 months, P=0.03) and to walk later independently (50% at 14.5 months versus 13.5 months, P=0.04), whereas timing of sitting unsupported was no different (50% at 7.4 months versus 7.2 months, P=0.9). Of very preterm infants, 16% were not able to walk at least three steps unsupported at 18 months after term which puts them at an increased risk for cerebral palsy. Some 35% of very preterm infants had to be readmitted to hospital during the first 24 months compared with 20% of control infants born at term (P<0.05). There was no difference between very preterm and term infants in respect to episodes of fever > 38.5 degrees C, episodes of coughing > 3 days and treatment with antibiotics. CONCLUSION: these data based on a national survey allow to quantify growth retardation, developmental delay and post-discharge health problems within the first 2 years in preterm infants born before 32(0)/7 weeks.

Child Development↗

PubMed2000

Plasma concentrations of granulocyte-macrophage colony-stimulating factor and interleukin-6 in septic and healthy preterms.

UNLABELLED: Plasma granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-6 (IL-6) concentrations were determined in 21 preterm infants with sepsis and nine healthy preterm neonates of the same postnatal age at sampling. Plasma GM-CSF levels were elevated at diagnosis in the septic preterms as compared to the healthy preterms (P = 0.01), but did not differ significantly on recovery. IL-6 levels were also elevated markedly at diagnosis (P = 0.0003), but decreased to normal on recovery as compared to the healthy preterm infants. GM-CSF levels were more prominent in septic preterms with neutropenia than those of non-neutropenic infants (P = 0.03). CONCLUSION: Preterm infants can produce high levels of granulocyte-macrophage colony-stimulating factor and interleukin-6 in response to bacterial sepsis.

Granulocyte-Macrophage Colony-Stimulating Factor↗

PubMed1997

Fatty acid composition of human milk during the 1st month after term and preterm delivery.

UNLABELLED: The fatty acid composition of human breast milk was determined longitudinally after term and preterm delivery by high resolution gas liquid chromatography. Milk samples were obtained at days 5, 10, 20 and 30 after term (n = 38) or preterm (n = 19) delivery. The saturated fatty acids C10:0 and C12:0 and the polyunsaturates linoleic acid (C18:2 omega-6) and alpha-linolenic acid (C18:3 omega-3) increased significantly from day 5 to day 10, whereas arachidonic acid (C20:4 omega-6), total omega-6 long-chain polyunsaturates (LCP), docosahexaenoic acid (C22:6 omega 3) and total omega-3 LCP decreased significantly. Term and preterm milk did not differ in percentage content of linoleic acid, alpha-linolenic acid and LCP at any time point. Preterm milk contained significantly more medium and intermediate chain fatty acids (C10:0, C12:0 and C14:0) than term milk on days 5 (12.28 vs 9.78%; P > 0.05), 10 (16.25 vs 12.62%; P > 0.05) and 20 (17.29 vs 13.47%; P > 0.005). CONCLUSION: The milk of mothers of preterm infants is not better suited to meet the high LCP requirements of their infants during the first weeks after birth. The slightly higher proportion of medium and intermediate chain fatty acids in preterm milk during the 1st month after birth might be advantageous for the fat and calcium absorption of preterm infants.

Chromatography, Gas↗

PubMed2000

Cord blood interleukin-10 levels are increased in preterm newborns.

UNLABELLED: Cell-mediated immunosuppression due to interleukin (IL)-10 may contribute to normal pregnancy. By contrast, delivery is associated with a predominance of T-helper-1 (Th1) cytokines (IL-12, interferon-gamma) and might be regarded as a graft rejection process. The aim of the study was to assess IL-10 and IL-12 levels in cord blood samples from newborns and their normal mothers in relation to the gestational age and type of delivery. Cord blood and serum samples were obtained from 31 term newborns (gestational age 38-42 weeks) and 40 preterm newborns (mean gestational age 32 weeks). Serum samples were obtained from 26 mothers of term newborns at birth. There were 18 term and preterm infants born by caesarean section. Measurements of IL-10 and IL-12 levels by ELISA were repeated in mothers 15 days after delivery and in 11 preterm infants (median 14 days of age). Cord blood IL-10 levels were significantly higher in preterm than in term newborns (median 17.0 versus 3.2 pg/ml, P = 0.0001), but were similar to term newborns and paired mothers (2.2 versus 1.0 pg/ml). Term and preterm newborns also showed similar cord blood IL-12 levels (median 349 versus 320 pg/ml), and these levels were significantly higher when compared to their paired mothers (median 14.5 pg/ml, P = 0.0003). Cord blood IL-10 levels showed a significant inverse correlation with gestational age (P = 0.0001). When preterm infants, at several weeks post-delivery, were compared to gestational age matched newborns, their IL-10 levels were similar (median 8.3 pg/ml) whereas IL-12 levels were clearly lower (147 pg/ml; P = 0.0007). The type of delivery (vaginal versus caesarean) did not influence cord blood IL-10 and IL-12 results. CONCLUSION: Cord blood IL-10 levels are increased in preterm newborns and may be due to the immunosuppression occurring during pregnancy and to fetal immaturity because these levels are inversely correlated with gestational age.

Female↗

PubMed1989

Evaluation of risk scoring in a preterm birth prevention study of indigent patients.

A total of 4591 indigent patients were scored for risk of preterm labor and birth by the Creasy et al. scoring system and delivered at greater than or equal to 20 weeks' gestation. Of 462 preterm deliveries (less than 37 weeks), only 39.6% were contributed by the 18.1% of patients who scored at high risk (score greater than or equal to 10). Of the 44 risk factors in the scoring system, 25 were not statistically significant by univariate chi 2 analysis. The spontaneous preterm birth rate was 8.0%. The positive predictive value of the Creasy et al. system was 18.3%. With multiple logistic analyses we excluded infrequent risk factors and identified five factors that remained significant (prepregnancy weight less than 45.5 kg, black race, single marital status, one preterm labor and delivery, preterm labor, and delivery greater than or equal to 2). With these five risk factors we created an equation that allowed identification of 12% of patients at high risk of preterm delivery with a positive predictive value of 21.9%. Because of the importance of previous preterm delivery, risk scoring of primigravid patients is of limited value.

Black or African American↗

PubMed1989

Controlled trial of hydration and bed rest versus bed rest alone in the evaluation of preterm uterine contractions.

Patients who are seen with uterine contractions but without documented change in cervical dilation or effacement are often treated with intravenous hydration before the initiation of intravenous tocolytic therapy. This is done with the intention of stopping uterine activity in patients with false preterm labor. A prospective randomized study was conducted to evaluate the effect of hydration on preterm uterine contractions in patients without proved preterm labor. A total of 28 patients were treated with bed rest and an intravenous bolus and subsequent continuous infusion of 5% dextrose in lactated Ringer's solution. A control group of 20 patients were treated with bed rest alone. Uterine activity and arrest of uterine contractions were compared between the two groups. Contractions stopped in 54% of the patients treated with hydration, whereas contractions stopped in 40% of the patients in the control group. This difference was not statistically significant. As a crossover study, those in the control group with contractions that continued after the initial observation period were subsequently treated with intravenous fluids. Only one patient in this group stopped contracting. Of all patients whose contractions with either therapy, 18% eventually were delivered of preterm infants. This included 20% of the hydration group and 14% of the control group. The use of hydration as a pretherapy indicator to differentiate true preterm labor from false preterm labor could not be supported by this study. In addition, patients whose contractions stopped with either hydration or bed rest are at increased risk of subsequent preterm delivery.

Bed Rest↗

PubMed1989

Infection and labor. V. Prevalence, microbiology, and clinical significance of intraamniotic infection in women with preterm labor and intact membranes.

Amniotic fluid was retrieved by amniocentesis from 264 patients with preterm labor and intact membranes admitted to Yale-New Haven Hospital from Jan. 1, 1985, to July 31, 1988. The prevalence of a positive amniotic fluid culture was 9.1% (24/264). A total of 111 patients (42%) delivered preterm neonates, and 24 (21.6%) of those had positive amniotic fluid cultures. The diagnostic indexes of the Gram stain of amniotic fluid in the prediction of a positive amniotic fluid culture were as follows: sensitivity, 79.1%; specificity, 99.6%; positive predictive value, 95%; and negative predictive value, 98%. Endotoxin was detected with the limulus amebocyte lysate assay in 4.9% (13/264) of patients with preterm labor. All patients with endotoxin in the amniotic fluid delivered preterm neonates. The three most frequently isolated organisms were Ureaplasma urealyticum (n = 6), Fusobacterium species (n = 5), and Mycoplasma hominis (n = 4). Clinical chorioamnionitis was present in only 12.5% of the patients with positive amniotic fluid cultures. Women with positive amniotic fluid cultures had lower gestational ages and more advanced cervical dilatation on admission than women with negative cultures. Preterm infants born to mothers with positive amniotic fluid cultures had a higher incidence of respiratory distress syndrome and infectious complications than preterm neonates born after negative amniotic fluid cultures. These data underscore the frequency and importance of intraamniotic infections in women with preterm labor.

Amniocentesis↗

PubMed1989

Relaxin in paired samples of serum and milk from women after term and preterm delivery.

In a study to determine if relaxin could be measured in milk and if so to correlate concentrations in milk and serum, paired samples of milk and serum were collected from 12 women 3 days after term delivery (term group), from 16 women 3 days after preterm delivery (preterm group), and from some of these patients 6 weeks after delivery (eight term and six preterm). Relaxin was measured by specific human relaxin radioimmunoassay. Relaxin from milk and sera behaved similarly in the relaxin radioimmunoassay and reverse-phase high-performance liquid chromatography. Concentrations of relaxin in sera and milk collected 3 days after delivery did not differ significantly within the term or preterm groups. Neither were there differences in relaxin levels in sera and milk between the term and preterm groups. At 6 weeks postpartum, relaxin was not measured in any sera but was measured in milk from six of eight patients in the term group and five of six patients in the preterm group. Relaxin concentrations in milk were higher in the preterm group. The presence of relaxin in milk at 6 weeks postpartum suggests a nonluteal site of synthesis.

Chromatography, High Pressure Liquid↗

PubMed1991

Does amniotic fluid index affect the accuracy of estimated fetal weight in preterm premature rupture of membranes?

Estimated fetal weights play a critical role in the management scheme of patients with preterm premature rupture of membranes but are often technically difficult to obtain in these patients because of low amniotic fluid volume. Previous studies have had conflicting data as to the accuracy of estimated fetal weights in preterm premature rupture of membranes. This study was undertaken to evaluate the effect of amniotic fluid index on the accuracy of estimated fetal weights in pregnancies complicated by preterm premature rupture of membranes. Over a 2-year period at Long Beach Memorial Medical Center, 98 patients with preterm premature rupture of membranes who had an ultrasonographic examination with estimated fetal weights and amniotic fluid index performed within 48 hours of delivery were identified and compared with a control group of 55 patients in preterm labor with normal amniotic fluid index for gestational age, also obtained within 48 hours of delivery. Shepard and Hadlock formulas were used to estimate fetal weight. Results were measured in percent error from the actual birth weight. All birth weights were less than 2000 gm. No statistical differences were identified. The value of amniotic fluid index did not affect the accuracy of predicted estimated fetal weight in preterm premature rupture of membranes. Predicted estimated fetal weight of patients with preterm premature rupture of membranes appears to be as accurate as predicted estimated fetal weight in pregnancies with normal amniotic fluid volumes.

Amniotic Fluid↗

PubMed1993

Sexual intercourse during pregnancy and preterm delivery: effects of vaginal microorganisms. The Vaginal Infections and Prematurity Study Group.

OBJECTIVE: Our aim was to investigate the influence of vaginal colonization with specific microorganisms on the relationship between sexual intercourse during pregnancy and preterm delivery. STUDY DESIGN: As part of a multicenter, prospective study interviews and physical examinations were conducted with and genital cultures were obtained from women seeking prenatal care from 23 to 26 weeks' gestation. At 31 to 36 weeks interviews were conducted with a randomly selected sample of these patients. RESULTS: Frequent intercourse (defined a priori as once per week or more) at 23 to 26 weeks was associated with a significantly reduced risk of subsequent preterm delivery in women without Trichomonas vaginalis, Mycoplasma hominis, or bacterial vaginosis, possibly because of the relative health and lack of complications in the pregnancies of those women engaging in sexual intercourse. Frequent intercourse was not significantly associated with preterm delivery in women with T. vaginalis, M. hominis, or bacterial vaginosis. Neither T. vaginalis, M. hominis, nor bacterial vaginosis was associated with preterm delivery among women with infrequent intercourse at 23 to 26 weeks. However, T. vaginalis and M. hominis were risk factors for preterm delivery among those with frequent intercourse. CONCLUSIONS: Frequent sexual intercourse by itself is not associated with an increased risk of preterm birth. However, women who are colonized with specific microorganisms and who engage in frequent intercourse are at increased risk of preterm delivery.

Adolescent↗

PubMed1994

Nitric oxide metabolites and preterm pregnancy complications.

OBJECTIVE: Intraamniotic infection may play a significant role in preterm labor and premature rupture of membranes. Synthesis of nitric oxide and its metabolites nitrite and nitrate purportedly are increased in infection. This project was designed to evaluate whether plasma or urine nitrate concentrations are increased in patients with either preterm labor or premature rupture of membranes in comparison with pregnant controls. STUDY DESIGN: A total of 42 patients between 24 and 35 weeks' gestation (20 with preterm labor; 14 with premature rupture of membranes, and 8 with premature rupture of membranes and contractions) and 35 additional patients without preterm labor or premature rupture of membranes (controls) had blood and urine collected for nitrate determination. Nitrate was reduced to nitrite and quantitated with the Griess reagent. RESULTS: The urine nitrate concentrations were significantly higher only in the preterm labor group compared with the control group (1.23 +/- 0.22 vs 0.67 +/- 0.05 mumol/mg creatinine, p < 0.05). The plasma nitrate level, however, was significantly higher in both the preterm labor and the premature rupture of membranes groups compared with the control group (52.47 +/- 10.11 and 40.05 +/- 5.38 mumol/L vs 16.29 +/- 2.89 mumol/L, p < 0.05). However, the concentrations of nitrate in the urine or plasma did not correlate with time from admission to delivery (p > 0.2). Finally, the presence of positive cervical or urine cultures, a clinical examination consistent with chorioamnionitis, or a maternal temperature > 100.4 degrees F was not associated with higher levels of nitrates in this small series of patients. CONCLUSION: Patients with preterm labor or premature rupture of membranes do have increased nitrate concentrations; however, this increased concentration is not predictive of impending delivery but may indicate that a subclinical infectious process is occurring.

Analysis of Variance↗

PubMed1995

Maternal serum placental alkaline phosphatase level and risk for preterm delivery.

OBJECTIVE: The purpose of this study was to determine whether elevated midtrimester serum placental alkaline phosphatase levels are predictive of preterm delivery. STUDY DESIGN: By use of banked serum specimens from a sample of women who had received maternal serum alpha-fetoprotein screening, placental alkaline phosphatase values for multiples of the median were obtained from 270 mothers who had experienced a preterm delivery and from 1598 mothers of term, appropriate-for-gestational-age infants. Specimens were analyzed for placental alkaline phosphatase by means of a monoclonal antibody enzyme-linked immunosorbent assay. Logistic regression was used to determine whether placental alkaline phosphatase was associated with preterm birth, while potential confounders were controlled for. RESULTS: Women with placental alkaline phosphatase levels > or = 2.0 multiples of the median were significantly more likely to be delivered of a preterm infant in the current pregnancy compared with women with levels < 2.0 multiples of the median (odds ratio 2.9, 95% confidence interval 2.1 to 3.9). The likelihood of preterm birth increased significantly with higher multiples of the median (p < 0.001). CONCLUSION: Women with elevated placental alkaline phosphatase levels are at increased risk for preterm delivery. Additional studies are needed to evaluate the clinical utility of placental alkaline phosphatase testing as a means of identifying mothers at risk for preterm birth.

Adolescent↗

PubMed1995

New perspectives for the effective treatment of preterm labor.

Preterm birth (before 37 completed weeks of gestation) continues to account for the vast majority of neonatal morbidity and mortality. The incidence of preterm birth can be reduced by appropriate social interventions and antenatal care. Currently available tocolytic agents suffer from low uterospecificity and prolong pregnancy only marginally, although postponement of birth by a few days may be of some value. Further progress is needed in at least four areas: prevention of preterm labor; identification of preterm labor; selection of candidates for tocolysis, and treatment of preterm labor. Effective, early treatment of vaginosis offers particular promise for the prevention of preterm labor and identification of specific biochemical markers will facilitate early detection of this process. Oxytocin antagonists offer greater specificity than current tocolytics and can be expected to show improved efficacy and risk profiles. Such compounds will allow more effective treatment of preterm labor with a lower risk of side effects.

Female↗

PubMed1995

Preterm premature rupture of membranes and abruptio placentae: is there an association between these pregnancy complications?

OBJECTIVE: Our purpose was to determine whether the incidence of abruptio placentae is increased in pregnancies with preterm premature rupture of membranes and to assess whether certain clinical risk factors in this group predispose them to have abruptio placentae. STUDY DESIGN: A retrospective cohort study over a 2.5-year period was performed. The study group consisted of 756 singleton pregnancies between 20 and 36 weeks' gestation complicated by preterm premature rupture of membranes and managed expectantly. The control group consisted of 11,240 pregnancies not complicated by preterm premature rupture of membranes and delivered during the same time period. The incidence of abruptio placentae was compared between the two groups. The study group of patients with preterm premature rupture of membranes was further subdivided into cases with (n = 38) and without abruptio placentae (n = 718) and compared. Clinical factors such as admission amniotic fluid index, history of bleeding before or after rupture of membranes, incidence of intrapartum fetal distress, and low 5-minute Apgar scores (< 6), latency-to-delivery interval, gestational age and weight at delivery, and incidence of amnionitis and endometritis were compared. RESULTS: The incidence of abruptio placentae in the study group (38/756, 5%) was significantly higher than that in the control group (97/11, 240, 0.9%) (p < 0.001, odds ratio = confidence interval). Comparison of cases with preterm premature rupture of membranes with and without abruptio placentae demonstrated both groups to have a similar gestational age at delivery, birth weight, latency-to-delivery interval, amniotic fluid index, and infectious morbidity. The group with abruptio placentae had a significantly higher incidence of bleeding before rupture of membranes (six of 38, 15% vs eight of 718, 1%; p < 0.005) and of intrapartum fetal distress (18/38, 46% vs 49/718, 7%; p < 0.0009). CONCLUSIONS: Pregnancies complicated by preterm premature rupture of membranes that are managed expectantly are at significant risk for abruptio placentae. Preterm premature rupture of membranes in such cases is more often preceded by bleeding. These abruptions may predispose the patient to intrapartum fetal distress.

Abruptio Placentae↗

PubMed1995

Relationship between placental histologic features and umbilical cord blood gases in preterm gestations.

OBJECTIVE: Our purpose was to test the hypothesis that placental histologic lesions reflect abnormal placental respiratory function in preterm gestations. STUDY DESIGN: A retrospective study of preterm deliveries from 22 to 32 weeks revealed 431 patients with umbilical venous or arterial blood gas values. Excluded were stillbirth, multiple gestations, placenta previa, maternal medical diseases, and fetal anomalies. Charts were reviewed for principal indication of delivery, diagnosis of labor, and mode of delivery. Blood gases were studied within 10 minutes of delivery on a model 178 automatic pH analyzer (Corning Med, Boston). Placental data included uteroplacental vascular lesions and related villous lesions, lesions of acute inflammation, chronic inflammation, and coagulation. Contingency tables and analysis of variance considered p < 0.05 as significant. RESULTS: Mean +/- SD umbilical vein pH was 7.36 +/- 0.07 (range 6.94 to 7.56) and umbilical artery pH was 7.30 +/- 0.08 (range 6.83 to 7.55). Increasing severity of uteroplacental thrombosis, villous lesions reflective of uteroplacental vascular pathologic mechanisms, avascular villi, histologic evidence of abruptio placentae, chronic villitis, and increased circulating erythrocytes were associated with decrease in umbilical vein and artery pH, increase in umbilical vein and artery PCO2, and decrease in umbilical vein and artery PO2. Histologic evidence of acute infection and villous edema were associated with a higher pH and PO2 and a lower PCO2 in both umbilical vein and artery. Umbilical vein or artery base excess was not related to placental lesions. Labor was not related to blood gas values in this data set, although a subset of cases of extremely preterm premature rupture of membranes and preterm labor who labored and were delivered by cesarean section had significantly poorer umbilical venous and fetal arterial blood gas values (all p < 0.005). Lesions related to poorer blood gas values were significantly more frequent in preterm preeclampsia and nonhypertensive abruptio placentae than in premature rupture of membranes or preterm labor. CONCLUSIONS: Changes in umbilical vein and artery pH, PO2, and PCO2 are significantly related to lesions of uteroplacental vascular pathologic mechanisms and intraplacental thrombosis. Placental lesions may be associated with chronic fetal distress by altering fetal oxygen availability and acid-base status. Placental immaturity resulting from prematurity may be associated with inefficient placental respiratory function and an increased likelihood of cesarean delivery in cases of premature rupture of membranes or preterm labor. Altered fetal acid-base balance plus excess numbers of circulating nucleated erythrocytes suggests that placental respiratory function is functionally abnormal when these lesions are present and leads to fetal tissue hypoxia.

Acidosis↗