Perinatal complications of gestational diabetes: the influence of the timing of the diagnosis

One hundred and thirty-nine single pregnancies complicated by gestational diabetes (GD) were reviewed. All pregnancies were treated by dietary counselling and insulin was restricted to those who presented an abnormal fasting or postprandial glycemia. Obstetrical and neonatal morbidity were evaluated according to the timing of the diagnosis of GD. Preterm labor, preeclampsia, cesarean section, macrosomia, depressed apgar at 1 min and hyperbilirubinemia were more frequent when the diagnosis was made later. Neonatal hypoglycemia was statistically more frequent among the infants of the insulin-treated mothers compared to those of the diet-treated mothers. Our data suggest that early diagnosis of GD might be important to reduce perinatal morbidity further.     

Birth trauma in insulin-dependent diabetic pregnancies.

Infants of insulin-dependent diabetic mothers are considered to be at high risk for birth trauma, presumably due to macrosomia. With current management of diabetes in pregnancy, including strict glycemic control, the rate and the severity of macrosomia should be decreased. The frequent use of ultrasound to assess fetal growth and weight and the use of cesarean delivery in case of fetal macrosomia should further decrease the risk for birth trauma in these infants. We therefore undertook this study to test the null hypothesis that with current management, insulin-dependent diabetic mothers have a rate of birth trauma similar to that of infants of nondiabetic mothers (normal glucose challenge test at 28 weeks' gestation) matched for gestational age at birth, presence or absence of labor, delivery method (vaginal versus cesarean), and race. We studied 118 insulin-dependent diabetic mothers (White classes B-RT) and 354 control subjects (three matches for each insulin-dependent diabetic mother). The rate of birth trauma was 3.4% in insulin-dependent diabetic mothers, not significantly different from controls (2.5%). Logistic regression analysis in which birth trauma was the dependent variable and diabetes, race, presence or absence of labor, mode of delivery (vaginal versus cesarean), infant weight, and infant head circumference were independent variables revealed that only vaginal delivery was a significant risk factor for birth trauma in infants in both groups (p = 0.01). Most frequently observed birth traumas were brachial plexus injury, facial nerve injury, and cephalohematoma. Of the three infants with brachial plexus injury (insulin-dependent diabetic mothers, two; controls, one), two were delivered with use of midforceps.(ABSTRACT TRUNCATED AT 250 WORDS)     

Umbilical artery pulsatility index in pregnancies complicated by insulin-dependent diabetes mellitus without hypertension

OBJECTIVE: In a group of diabetic pregnant women, the umbilical artery pulsatility index (PI) was compared with both pregnancy complications and perinatal outcomes. METHOD: We evaluated 67 women with pregnancies complicated by insulin-dependent diabetes mellitus (IDDM), without hypertension. For the study we took the last umbilical PI value before delivery into consideration. Doppler results were not used for patient management. Umbilical artery PI was correlated with the route of delivery and the following perinatal complications: intrauterine growth retardation; cesarean sections for acute fetal distress; respiratory distress syndrome (RDS); neonatal hyperbilirubinemia; hypocalcemia; hypoglycemia; macrosomia, and neonatal intensive care unit (NICU). RESULTS: Among the 67 diabetic patients enrolled in this study, 44 (66%) had umbilical PIs ranging from the 5th to the 95th percentile (PI mean +/- SD = 1.2 +/- 0.3), while 23 (34%) had PIs above the 95th percentile (PI mean +/- SD = 1.6 +/- 0.3). Among the group with pathologic umbilical PIs, analysis of the data revealed a significantly higher incidence of both cesarean sections for acute fetal distress and perinatal complications: RDS; hyperbilirubinemia; hypoglycemia, and the need for NICU, respectively. CONCLUSION: In 34% of the diabetic pregnant women without hypertension, we found increased vascular resistances. Among these patients the incidence of perinatal complications was higher, and both closer maternal metabolic control and stricter care of fetal conditions are needed.     

Isolated oligohydramnios in term pregnancy as an indication for induction of labor.

OBJECTIVE: To evaluate the outcome of active induction of labor for isolated oligohydramnios in low-risk term gestation. METHODS: This retrospective study analyzed the obstetric and perinatal outcome of 412 singleton term pregnancies with cephalic presentation and no maternal risk factors or fetal abnormalities. Two groups were compared: 206 deliveries after induced labor for isolated oligohydramnios, and 206 deliveries matched for gestational age following spontaneous labor with normal amniotic fluid index. RESULTS: The overall rate of cesarean deliveries and cesarean deliveries for nonreassuring fetal status, and operative vaginal delivery rates and those for nonreassuring fetal status were higher in the oligohydramnios group than in the control group. There were no differences between groups in neonatal outcome or perinatal morbidity or mortality. CONCLUSION: Active induction of labor in term low risk gestations with isolated oligohydramnios translated into higher labor induction, operative vaginal delivery and cesarean section rates. This led to increased maternal risk and an increase in costs with no differences in neonatal outcome.     

Effect of mode of delivery on incidence of respiratory distress syndrome

The effect of route of delivery on incidence of respiratory distress syndrome (RDS) has been controversial. While some investigators have reported no difference in RDS rates in infants born by cesarean section as compared to vaginal delivery, others have shown a significant increase in risk for RDS among infants born by cesarean section. Data from the 297 patients comprising the placebo group in the recently completed collaborative study of antenatal steroid therapy in the prevention of neonatal RDS, were analyzed to determine the effect of mode of delivery on RDS. The results indicate that infants born by cesarean section without labor have a higher risk for neonatal RDS than infants born vaginally or by cesarean section after a trial of labor.     

Treatment of premature labor in insulin-dependent diabetic women

This retrospective study was designed to analyze the safety and efficacy of beta-sympathomimetic agents used to treat premature labor in insulin-dependent diabetic women. The study evaluated 12 insulin-dependent diabetic women who experienced 15 pregnancies complicated by premature labor. A group of 30 insulin-dependent diabetic women who delivered at term served as matched controls. Treatment consisted of parenteral and oral administration of beta-sympathomimetic drugs (ritodrine and isoxsuprine). Premature labor was diagnosed, and tocolytic treatment was initiated at a mean gestational age of 31.5 +/- 0.9 weeks. The mean gestational age at the time of delivery was 35.8 +/- 0.5 weeks. Delivery was delayed in the study group by a mean of 30.5 +/- 6.6 days. No fetal or infant deaths occurred in the study group, and there was no difference between the two groups in the incidence of neonatal morbidity. No maternal complications occurred. There were no significant differences in hemoglobin A1 levels between the two groups at any period of gestation. Thus, beta-sympathomimetic drugs may be used safely to treat premature labor in patients with insulin-dependent diabetes, provided they are administered under strictly controlled clinical settings.     

中心电子监护系统的临床应用

目的 探讨使用中心电子监护系统对提高产科质量的作用。方法 对１９７９年１１月 １９９８年３月在我院分娩的孕周≥３７周的１２１６例孕妇进行ＣＥＭＳ监护,并与１９９６年１１月至１９９７年３月在我院分娩的孕周≥３７周、未行ＣＥＭＳ监护的１１３７例孕妇（对照组）进行比较,分析两组胎儿窘迫发生率,新生儿窒息发生率,剖宫痃和阴道手术率。结果 姐与则组胎儿窘迫发生率分别为９．８％、１２．８％;新生窒息发生率分别     

Isolated oligohydramnios in term pregnancy as an indication for induction of labor

Objective. To evaluate the outcome of active induction of labor for isolated oligohydramnios in low-risk term gestation.

Methods. This retrospective study analyzed the obstetric and perinatal outcome of 412 singleton term pregnancies with cephalic presentation and no maternal risk factors or fetal abnormalities. Two groups were compared: 206 deliveries after induced labor for isolated oligohydramnios, and 206 deliveries matched for gestational age following spontaneous labor with normal amniotic fluid index.

Results. The overall rate of cesarean deliveries and cesarean deliveries for nonreassuring fetal status, and operative vaginal delivery rates and those for nonreassuring fetal status were higher in the oligohydramnios group than in the control group. There were no differences between groups in neonatal outcome or perinatal morbidity or mortality.

Conclusion. Active induction of labor in term low risk gestations with isolated oligohydramnios translated into higher labor induction, operative vaginal delivery and cesarean section rates. This led to increased maternal risk and an increase in costs with no differences in neonatal outcome.     

Neonatal polycythemia in infants of insulin-dependent diabetic mothers

The rate of neonatal polycythemia was determined prospectively in 34 infants of diabetic mothers pair-matched to 34 infants of nondiabetic mothers (control group) for site of sampling, time of sampling, time of cord clamping, gestational age, mode of delivery, and one- and five-minute Apgar scores. Polycythemia (venous hematocrit greater than or equal to 65%) was present in 29.4% of infants of diabetic mothers and 5.9% of control subjects (P less than .03). Mean nucleated red blood cell counts were significantly higher in infants of diabetic mothers than in controls. Polycythemia did not correlate with higher maternal hemoglobin A1 concentration or with increased infant weight percentile, but did correlate with neonatal hypoglycemia. The authors speculate that increased erythropoiesis exists in infants of diabetic mothers and might be subsequent to fetal hypoxemia due to fetal hyperglycemia, hyperinsulinism, and hyperketonemia.     

Active induction management of labor for diabetic pregnancies at term; mode of delivery and fetal outcome--a single center experience

OBJECTIVES: To evaluate the mode of delivery in diabetic pregnancies at term following induction of labor with vaginal application of prostaglandin E2 (PGE2), and to identify possible predictors of successful vaginal delivery. PATIENTS AND METHODS: The study group consisted of 105 women with diabetic pregnancies at term admitted for induction of labor; 84 (80%) had gestational diabetes (GDM) and 21 (20%) type 1 diabetes. Findings were compared with women who underwent elective induction of labor (n=115), and women with normal spontaneous onset of labor (n=510). Women with previous cesarean section (CS) were excluded from both study and control groups. RESULTS: Maternal age and gravidity were significantly higher in the study group than the control groups (age: 31.4+/-5, 28+/-5.0 and 28.1+/-4.8 years, respectively; gravidity: 3.0+/-1.9, 2.5+/-1.6, and 2.1+/-1.4, respectively; P<0.001 for both) and gestational age and nulliparity rate were significantly lower (gestational age: 38.6+/-1.1, 40.2+/-1.3 and 39.3+/-2.7 weeks, respectively; nulliparity: 34.6, 45.2, 51.6%, respectively; P<0.002 for both). There were no between-group differences in the incidence of oligohydramnios, number of PGE2 applications used, birth weight, rate of non-reassuring fetal heart rate pattern leading to CS, and rate of low 5 min Apgar score (<7). The rate of CS in the study group (18.2%) was significantly higher than in the spontaneous labor group (9%) but similar to the elective induction group (14.8%). On stepwise analysis, only nulliparity (OR 4.56, 95% CI 1.11-18.67, P=0.035) was independently and significantly associated with increased risk of CS. Within the study group (R2=0.257, P=0.002), type 1 diabetes (OR 2.4, 95% CI 1.04-5.51) was independently and significantly associated with increased risk of CS. CONCLUSION: In diabetic pregnancies, induction of labor at term with vaginal PGE2 is successful in approximately 82% of patients, but yields a significantly higher CS rate compared to uncomplicated pregnancies. Nulliparity and diagnosis of type 1 diabetes are independently and significantly associated with increased risk of CS. CONDENSATION: In diabetic pregnancies, induction of labor at term is successful in 82% of patients, but yields higher CS rates compared to uncomplicated pregnancies.     

Prospective delivery of reliably dated term infants of diabetic mothers without determination of fetal lung maturity: comparison to historical control

Objective: To determine whether omitting fetal lung maturity (FLM) testing prior to delivery in term pregnancies complicated by gestational (GDM) and pregestational diabetes mellitus would increase the risk of neonatal respiratory distress syndrome (RDS). Methods: In a 2-year study (1990-91), 1457 pregnant women with accurately dated pregnancies were enrolled after 37 completed weeks and prospectively followed through delivery without FLM testing (study group). The prevalence of RDS and other neonatal outcomes was compared with a historical control group (n = 713, 1988-89) who had undergone determination of lecithin/sphingomyelin ratio prior to delivery at term. Logistic regression analysis was performed to determine independent predictors of RDS. Results: The study group compared to the control group had less severe diabetes: diet-controlled GDM, 35% vs. 18%, respectively; insulin-requiring GDM, 42% vs. 42%, respectively; undiagnosed type-2 diabetes, 14% vs. 31%, respectively; and pre-existing diabetes, 9.6% vs. 8.8%, respectively, p < 0.001. RDS rates in the study group (0.8%) and control group (1.0%) were not significantly different, nor were rates of resuscitation at delivery, neonatal intensive care admission or hospitalization days. Logistic regression analysis found only Cesarean delivery to be independently predictive (adjusted OR 2.21, 95% CI 2.04-2.27) of RDS. Non-predictive variables included FLM testing, diabetic classification, insulin use, poor third-trimester glycemic control, chronic hypertension, pre-eclampsia, labor, neonatal gender, gestational age or large-for-gestational-age fetuses. Conclusions: Routine FLM testing did not change the RDS prevalence in reliably dated, term infants of diabetic mothers and should be abandoned. Delivery by Cesarean section was associated with increased RDS.     

Diabetes and pregnancy. Maternal risk factors and neonatal morbidity

BACKGROUND: To verify in our population the incidence of infants of mother with insulin dependent diabetes mellitus (IDDM) or gestational diabetes (GD) and to evaluate the maternal characteristics influencing neonatal outcome. METHODS: The study was retrospectively performed on 6179 infants born between 1995 and 1998 at the Obstetric Clinic of the University of Messina and referred the Division of Neonatology. The following groups have been selected: group A (offsprings of IDDM mothers), group B (offsprings of DG mothers), group C and group D, controls, (2 infants of the same sex and gestational age born before and after the infants of group A and group B, respectively). The parameters analyzed were: diabetic familiarity, age, weight and body mass index (BMI) of the mothers, delivery, gestational age, weight at birth, neonatal outcome. RESULTS: The infants of IDDM mothers were 3% and the infants of GD mothers were 0.8%. Group A and group B present a significantly higher incidence of: diabetic familiarity, cesarean section, macrosomia, hypoglycemia, hypocalcemia, hyperbilirubinemia. The GD mothers had weight and BMI higher than IDDM mothers. The infant weight did not correlate with maternal weight and BMI. CONCLUSIONS: These data suggest that in our population GD is underestimated, metabolic control in pregnancy is insufficient, obstetric practices are too invasive, neonatal outcome is verosimely correlated only to metabolic control.     

Surfactant associated protein (SAP-35) in amniotic fluid from diabetic and nondiabetic pregnancies

We have recently shown that, with the current management of insulin-dependent diabetes during pregnancy, infants of diabetic mothers are at no greater risk of respiratory distress syndrome (RDS) than an appropriately matched control population. A previous study suggested a selective inhibition of surfactant associated protein of 35,000 daltons (SAP-35) in the amniotic fluid of diabetic pregnancies. In order to determine whether a selective inhibition of SAP-35 occurs in well controlled, insulin-dependent diabetic pregnancies, we compared SAP-35 concentration and lecithin/sphingomyelin (L/S) ratios in amniotic fluid from 30 well controlled, insulin-dependent women with 30 nondiabetic pregnant women pair-matched for gestational age, race, and indication for amniocentesis. Gestational ages ranged from 30-43 weeks, with a mean of 36.5 +/- 2.5 weeks, in both groups. Surfactant associated protein-35 was measured by an enzyme-linked capture immunoassay specific for SAP-35 and its oligomers. Mean +/- SEM SAP-35 was 3.7 +/- 0.4 micrograms/mL (N = 30) in the diabetic group, not significantly different from 5.0 +/- 1.1 micrograms/mL (N = 30) in the control group (P greater than .05). Mean L/S ratios were also not different: 2.4 +/- 0.1 (diabetic) compared with 2.3 +/- 0.1 (control); P greater than .05. The rate of RDS was similar in both groups. We conclude that in well controlled diabetic pregnancies, fetal lung maturation, as assessed by the L/S ratio, SAP-35 concentration, and outcome, is not adversely affected.     

Intrapartum management of nonvertex second-born twins: a critical analysis.

OBJECTIVE: Our purpose was to assess the impact of the mode of delivery--vaginal delivery versus cesarean section--on the perinatal outcomes of the second-born breech twins. STUDY DESIGN: This study was a retrospective analysis of second-born breech twins with a gestational age of > or =24 weeks at the onset of labor. The patients are divided into three groups: cesarean section without labor (group I), cesarean section after labor (group II), and vaginal breech delivery (group III). RESULTS: There were 141 patients: 40 in group I, 66 in group II, and 35 in group III. There was no birth injury or neonatal death. Group II had one fetus with grade II intraventricular hemorrhage. There was no significant difference among the groups with regard to gestational age, birth weight, hyaline membrane disease, Apgar scores at 1 and 5 minutes, and cord blood gas indices, except venous pH in infants with birth weights <1500 g. CONCLUSIONS: Vaginal delivery of breech second-born twins, with gestational ages of at least 24 weeks, especially those with birth weights of > or =1500 g, appears to be a safe alternative to cesarean section.     

Mode of delivery in pregnancies with suspected fetal growth restriction following induction of labor with vaginal prostaglandin E2

BACKGROUND: Many fetuses below the 10th percentile for gestational age are uncompromised. We aimed to evaluate the mode of delivery and immediate neonatal outcome in pregnancies with suspected fetal growth restriction (FGR) and normal antenatal assessment following induction of labor with vaginal application of prostaglandin E2 (PGE2). METHODS: Ninety women with suspected FGR (sonographic estimated fetal weight < 10th percentile) with normal oxytocin contraction test (OCT), biophysical profile (BPP) and reassuring fetal heart rate underwent induction of labor with vaginal application of PGE2 tablets. The findings were compared with 115 women admitted for induction of labor because of decreased fetal movement (group 2) and with 510 women with normal spontaneous onset of labor (group 3). RESULTS: There were no between-group differences in mean maternal age, gravidity, parity, nulliparity rate, number of tablets used or rate of patients receiving more than one PGE2 application. The rate of cesarean section (CS) in the study group (8.9%) was similar to the rate in groups 2 and 3 (14.8% and 9.0%, respectively). The incidence of nonreassuring fetal heart rate pattern leading to cesarean delivery was higher in the study group, but the rate of low 5-min Apgar scores (< 7) was similar in all groups. A logistic regression model and forward likelihood analysis yielded no single significant variable associated with increased risk of cesarean delivery. CONCLUSIONS: In selected cases of suspected FGR with reassuring fetal heart rate and normal OCT and BPP, induction of labor with vaginal PGE2 may yield a similar immediate fetal outcome and CS rate as in uncomplicated, induced or spontaneous deliveries.     

Vaginal birth after cesarean in the diabetic gravida

OBJECTIVE: To compare the delivery outcomes in term diabetic patients without a prior cesarean delivery to those attempting vaginal birth after cesarean (VBAC). STUDY DESIGN: A retrospective chart review study was performed of singleton pregnancies complicated by class A-2-R diabetes who delivered at > or = 37 weeks from 1991 to 1997. Exclusion criteria were prior classical or low vertical cesarean, more than one prior cesarean delivery, fetal structural defects or any contraindications to labor. Outcome measures were compared for patients without prior cesarean (group 1) to those with a VBAC attempt (group 2). RESULTS: One hundred fifty-nine patients, 127 patients without a prior cesarean delivery and 32 patients with a VBAC attempt, met all the study criteria. The cesarean delivery rate was 26.3% (34/127) in group 1 and 56.3% (18/32) in group 2 (VBAC success rate, 43.7%). There were no cases of uterine rupture. There were no differences in the frequency of endometritis rates or neonatal intensive care unit admission, whether vaginal or cesarean delivery occurred. CONCLUSION: VBAC success rates appeared to be lower for diabetic gravidas as compared to those for nondiabetic women reported in the literature. Although maternal and neonatal complication rates were low, further studies are necessary to determine the safety of VBAC in this population.     

Obstetrical correlates and perinatal consequences of neonatal hypoglycemia in term infants

Objective: To determine independent perinatal and intrapartum factors associated with neonatal hypoglycemia.

Method: Of singleton pregnancies delivered at term in 2013; 318 (3.8%) neonates diagnosed with hypoglycemia were compared to 7955 (96.2%) neonate controls with regression analysis.

Results: Regression analysis showed that independent prenatal factors were multiparity (odds-ratio [OR]?=?1.61), gestational age (OR?=?0.68), gestational diabetes (OR?=?0.22), macrosomia (OR?=?4.87), small for gestational age neonate [SGA] (OR?=?6.83) and admission cervical dilation (OR?=?0.79). For intrapartum factors, only cesarean section (OR?=?1.57) and last cervical dilation (OR?=?0.92) were independently significantly associated with neonatal hypoglycemia. For biologically plausible risk factors, independent factors were cesarean section (OR?=?4.18), gentamycin/clindamycin in labor (OR?=?5.35), gestational age (OR?=?0.59) and macrosomia (OR?=?5.62).

Mothers of babies with neonatal hypoglycemia had more blood loss and longer hospital stays, while neonates with hypoglycemia had worse umbilical cord gases, more neonatal hypoxic conditions, neonatal morbidities and NICU admissions.

Conclusion: Diabetes was protective of neonatal hypoglycemia, which may be explained by optimum maternal glucose management; nevertheless macrosomia was independently predictive of neonatal hypoglycemia. Cesarean section and decreasing gestational age were the most consistent independent risk factors followed by treatment for chorioamnionitis and SGA. Further studies to evaluate these observations and develop preventive strategies are warranted.     

Maternal and fetal beta-endorphin release in response to the stress of labor and delivery

In order to clarify the stress effect of labor on maternal and neonatal plasma levels of beta-endorphin, we measured this peptide in samples taken from 40 pregnant patients and their neonates at the time of normal vaginal delivery (n = 15), and at cesarean section performed either in early labor (n = 13) or prior to labor (n = 12). The mean (+/- SE) maternal plasma concentration of beta-endorphin in the vaginal delivery group was 40.3 +/- 5.6 fmol/ml, which was significantly higher than that in their neonates (21.3 +/- 2.9 fmol/ml). In contrast, maternal levels of beta-endorphin in the cesarean section groups (8.2 +/- 1.2 and 8.5 +/- fmol/ml) were significantly lower than those in their neonates (23.3 +/- 5.6 and 15.6 +/- 2.8 fmol/ml). Concentrations of beta-endorphin in mothers delivered vaginally were also significantly higher than those in mothers delivered by cesarean section. However, there was no difference in mean cord levels of beta-endorphin among the three groups. These findings indicate that neither the presence or absence of labor affects fetal plasma beta-endorphin secretion and the stress of labor and delivery produces a marked increase in maternal release of beta-endorphin.     

Complication of insulin-dependent diabetic pregnancies by preeclampsia and/or chronic hypertension: analysis of outcome

The significance of hypertensive complications of insulin-dependent diabetic pregnancies (IDDP) has not been well examined since the early reports of Pedersen, which demonstrated an increased risk of neonatal death in women with pregnancy induced hypertension (PIH). To assess the effect of both PIH and chronic hypertension (CH) on outcome of IDDP managed using contemporary obstetrical and diabetic management, we reviewed the records of all 199 IDDP delivered at our institution over a 7-year period. Patients were classified as having PIH (Group 1, n = 37), CH (Group 2, n = 18) or both (Group 3, n = 4) on the basis of standard clinical criteria. All other IDDP were placed in the control group (Group 4, n = 140). Comparing all groups, significant differences were found for maternal age (P less than .0001) and distribution among White's Classes (P less than .0001). There was no significant difference in estimated gestational age (EGA) at delivery, birthweight, Apgar scores, hypoglycemia, hyperbilirubinemia, or congenital anomalies. Intrauterine fetal death (IUFD) was no more common in Groups 1, 2 or 3 than in Group 4; however, IDDP with CH were significantly more likely to have had previous stillbirths than IDDP with PIH (P = .011) or control IDDP (P = .017). Contrary to common clinical belief, the "stress" of CH and PIH did not offer protection to the newborn in the development of RDS or HMD. In fact, Group 3 infants had a higher rate of HMD than control infants (P = .024).(ABSTRACT TRUNCATED AT 250 WORDS)     

Increased immunoreactive erythropoietin in cord plasma and neonatal bilirubin production in normal term infants after labor

The purpose of this investigation was to compare immunoreactive erythropoietin levels in umbilical cord plasma and neonatal bilirubin production in infants born of normal women who delivered with or without labor. Two groups of term (38 to 42 weeks) singleton pregnancies were compared: 1) those delivered by repeat elective cesarean section without prior labor (N = 17), and 2) those delivered vaginally or by cesarean section after labor (N = 24). None of the infants was asphyxiated, and there was no difference in Apgar scores between the no-labor and labor groups. The cord plasma erythropoietin levels were lower in the infants of women who had repeat elective cesarean section without labor than in those whose mothers had labor before delivery (Wilcoxon rank sum test, P less than .025). The median erythropoietin for the no-labor group was 22.9 mU/mL compared with 38.8 mU/mL for the labor group. The pulmonary excretion rate of carbon monoxide (VeCO), an index of bilirubin production, for the no-labor group was 14.3 +/- 6.2 SD microL/kg per hour compared with 18.0 +/- 4.9 SD microL/kg per hour for the labor group (P less than .05). The hemoglobin concentration for the no-labor group was 16.0 +/- 1.5 SD g/dL compared with 17.7 +/- 2.2 SD g/dL for the labor group (P less than .05). The VeCO correlated with the hemoglobin concentration (N = 32, r = 0.37, P less than .05). The results of the present study suggest that labor is normally associated with increases in the cord plasma erythropoietin level.(ABSTRACT TRUNCATED AT 250 WORDS)