Histological chorioamnionitis and the risk of early intraventricular hemorrhage in infants born < or =28 weeks gestation.

OBJECTIVE: To test the hypothesis that histological chorioamnionitis (CA) is not associated with increased risk of early onset intraventricular hemorrhage (IVH). STUDY DESIGN: Clinical data were prospectively collected for 62 consecutive neonates born before 28 weeks of gestation. Placental histology for CA was performed by a pathologist unaware of the head ultrasound scan (HUS) results. The first HUS was obtained by 30 minutes of life. Follow-up HUS were performed before 24 hours and again at 48 to 72 postnatal hours of life. An IVH (grade I to IV) at less than 72 hours of life was deemed an early hemorrhage. RESULTS: Nine of the 62 (14.5%) infants had early onset IVH. In all, 29 infants were born to women with histological evidence of CA; 33 infants did not have CA. Infants did not differ in birth weight, gestational age, sex, cord blood pH, 5-minute Apgar score of <7, cesarean delivery, prenatal use of steroids, administration of tocolytics, need for resuscitation, presence of pneumothorax, platelet count at birth, or use of surfactant. Early IVH rates (3/29 in CA vs 6/33 in non-CA) were similar (p=0.48). Two infants in each group with early IVH died before 2 weeks of age. Five additional infants from the CA group developed IVH at more than 72 postnatal hours of life (late onset IVH), and two of those infants progressed to develop periventricular leukomalacia (PVL). In contrast, only three non-CA infants had late IVH and none developed PVL. Logistic regression confirmed that no perinatal variables including CA were associated with early onset IVH. CONCLUSION: Chorioamnionitis is not associated with increased risk of early IVH.     

Agreement of carbon dioxide levels measured by arterial, transcutaneous and end tidal methods in preterm infants < or = 28 weeks gestation.

OBJECTIVE: To assess the agreement of transcutaneous carbon dioxide (TcPCO(2)) and end tidal carbon dioxide (PetCO(2)) with arterial carbon dioxide (PaCO(2)) values in infants < 28 weeks gestational age. STUDY DESIGN: In all, 27 ventilated preterm infants were prospectively studied. PaCO(2) was compared with TcPCO(2) and PetCO(2) measured at three similar time points within first 24 hours after birth. RESULTS: The Intraclass correlation coefficients for TcPCO(2) and PaCO(2) were 0.45, 0.73 and 0.53; and for PetCO(2) and PaCO(2) were 0.61, 0.56 and 0.57 at 4, 12 and 24 hours after birth, respectively. CONCLUSION: A moderate agreement with a wide variation in individual values was observed between noninvasive methods and PaCO(2) in preterm infants in the first 24 hours. Noninvasive monitoring methods cannot be substituted for PaCO(2) analyses in preterm infants during this critical period.     

Cervicovaginal fibronectin and cervical length at 23 weeks of gestation: relative risk of early preterm delivery

Objectives To establish the prevalence of cervicovaginal fetal fibronectin positivity at 23 weeks of gestation in a routine population of singleton pregnancies and determine the relative risk of spontaneous delivery before 33 weeks in women with a fibronectin positive result.
Design Prospective clinical study.
Setting Inner city antenatal clinic.
Population Singleton pregnancies attending for routine antenatal care.
Methods Cervicovaginal fetal fibronectin and cervical length were measured at 23 weeks of gestation. The distribution of fibronectin positivity within subgroups according to maternal characteristics was calculated and the relative risk of spontaneous delivery before 33 weeks was estimated.
Main outcome measures Prevalence of a fibronectin positive result and its relation to cervical length measurement and spontaneous preterm delivery before 33 weeks.
Results Of 5146 women participating in the study, 182 (3.5%) had a fibronectin positive result and 76 (1.5%) had a cervical length of ≤ 15 mm. Fibronectin positive women were more likely to be Afro-Caribbean in origin, to have had a previous second trimester miscarriage and to have a short cervix. In the 5068 women who were managed expectantly, the significantly independent relative risk of spontaneous delivery at < 33 weeks was 46.2 (95% CI 18.8–113.6), for cervical length of ≤ 15 mm, 8.1 (95% CI 3.8–17.5) for a fibronectin positive result, and 4.4 (95% CI 2.2–9.1) for cigarette smoking.
Conclusion Fibronectin positivity at 23 weeks of gestation provides useful prediction of pregnancies at risk of spontaneous preterm delivery before 33 weeks, with a relative risk that is twice as high as cigarette smoking, but is a sixth of that of cervical length.     

Mode of delivery in the early preterm infant (<28 weeks)

Elective caesarean section for women in labour with an immature baby might reduce the chances of fetal or neonatal death, but might also increase the risk of maternal morbidity. A review (updated in February 2004) of randomised trials comparing a policy of elective caesarean section versus expectant management with recourse to caesarean section produced six studies involving only 122 women. Differences in fetal outcome did not reach significance, but mothers undergoing elective caesarean section were more likely to have serious morbidity. Scientifically, the evidence remains inadequate. Clinically, the recommendation is that prematurity is not, in itself, an indication for caesarean section. In a survey from Israel, published in December 2004, of 2955 very low birthweight infants born at 24–34 weeks of gestation, the overall caesarean section rate was 51.7%, and the mortality rate among babies prior to discharge was lower after caesarean section (13.2 versus 21.8%). After adjustment using multiple logistic regression, caesarean section had no effect on survival except in a subgroup with amnionitis, and it was again concluded that caesarean section cannot be routinely recommended unless there are other indications. A decision model developed in the USA has compared costs and health outcomes of two options for managing labour at 24 weeks of gestation. The probabilities of both intact survival (16.8 versus 12.9%) and survival with major morbidity (39.2 versus 19.4%) are higher with willingness to perform caesarean section, but less aggressive management is the more cost-effective strategy. Large studies are few and recruitment to such studies is perceived as a major problem. For clinicians, the decision will be influenced by local circumstances.     

Low maternal age and neonatal survival of extremely preterm twins (20-28 weeks of gestation)

OBJECTIVE: We investigated the relationship between low maternal age and neonatal survival among extremely preterm twins. METHODS: This was a retrospective cohort study on live births of extremely preterm twins delivered to teenaged mothers (aged 15-19 years) in the United States within the period 1995 through 1998. Overall neonatal and early and late neonatal mortality in this category was compared with that of a similar group of twins born to young adult mothers (aged 20-29 years). We used the generalized estimating equation framework in computing relative risks after adjusting for intracluster correlations. RESULTS: Analysis involved 2,290 extremely preterm liveborn twins of teenaged mothers and 8,709 born to young adult mothers. Overall, neonatal mortality was 29% higher among the extremely preterm twins born to teenaged mothers (adjusted odds ratio [OR] 1.29; 95% confidence interval [CI] 1.04%, 1.59%). The disparity in neonatal survival was chiefly in the early neonatal period (adjusted OR 1.34; 95% CI 1.07%, 1.67%), while late neonatal mortality was comparable (adjusted OR 0.91; 95% CI 0.58%, 1.42%). In addition, twins of teenaged mothers had significantly higher level of mortality, except for the birth weight category of 1,000-1,499 g. CONCLUSION: Low maternal age was found to be associated with elevated risk of neonatal death among extremely preterm twins. The preponderance of deaths among extremely preterm twins of teenaged mothers in the early neonatal period appeared to be responsible for the disparity in survival. This information may be useful for targeted interventions aimed at enhancing survival of extremely preterm twins born to teenagers, as well as for instituting optimal management options in the clinical setting. LEVEL OF EVIDENCE: II-2     

Safety and efficacy of vaginal birth after cesarean attempts at or beyond 40 weeks of gestation

OBJECTIVE: To compare rates of vaginal birth after cesarean (VBAC) failure and major complications in women attempting VBAC before and after the estimated date of delivery (EDD) METHODS: This was a 5-year retrospective cohort study in 17 university and community hospitals of women with at least 1 prior cesarean delivery. Women who attempted VBAC before the EDD were compared with those at or beyond 40 weeks of gestation. Logistic regression analyses were performed to assess the relationship between delivery beyond the EDD and VBAC failure or complication rate. RESULTS: A total of 11,587 women in the cohort attempted VBAC. Women past 40 weeks of gestation were more likely to have a failed VBAC. After controlling for confounders, the increased risk of a failed VBAC beyond 40 weeks remained significant (31.3% compared with 22.2%, odds ratio 1.36, 95% confidence interval 1.24-1.50). The risk of uterine rupture (1.1% compared with 1.0%) or overall morbidity (2.7% compared with 2.1%) was not significantly increased in the women attempting VBAC beyond the EDD. When the cohort was defined as 41 weeks or more of gestation, the risk of a failed VBAC was again significantly increased (35.4% compared with 24.3%, odds ratio 1.35, 95% confidence interval 1.20-1.53), but the risk of uterine rupture or overall morbidity was not increased. CONCLUSION: Women beyond 40 weeks of gestation can safely attempt VBAC, although the risk of VBAC failure is increased.     

Serum lipid levels at 28-32 weeks gestation and hypertensive disorders.

BACKGROUND: The etiology and pathogenesis of hypertensive disorders complicating pregnancy are poorly understood, and the definition of these disorders is controversial. METHODS: In a prospective study, 470 primigravida women between 28 and 32 weeks of pregnancy were evaluated for serum levels of total cholesterol, low-density lipoprotein (LDL) and high-density lipoprotein (HDL) cholesterol, and triglyceride. Afterward, they were observed for any symptoms of preeclampsia and gestational hypertension until 40 weeks of gestational age. We than compared the serum lipid levels among women with preeclampsia and gestational hypertension with those of matched women with normal pregnancies. RESULTS: The numbers of patients developing preeclampsia and gestational hypertension were 25 (5.3%) and 32 (6.8%), respectively. At the beginning of the study, the mean values of serum triglyceride levels between women who later experienced preeclampsia or gestational hypertension and those who did not differed significantly (p < 0.0001, p < 0.03). CONCLUSION: Although many cases of gestational hypertension represent latent essential hypertension based on the lipid levels, some of these women display true pregnancy-induced hypertension or nonproteinuric preeclampsia.     

Mortality and morbidity in infants born between 20 and 28 weeks gestation

Of 149 infants with ultrasound evidence of gestational age, born in Ninewells Hospital at between 20 and 28 weeks gestation over a 5-year period, 50 were alive at birth. Of these infants, 21 died within 1 week, a further three died within 1 month and a further two within 18 months. Of the 24 survivors, 8 (33%) have significant handicap. The obstetric factors leading to delivery and the mode of delivery are discussed.     

Impact of race and ethnicity on the outcome of preterm infants below 32 weeks gestation.

OBJECTIVES: To determine the impact of race/ethnicity on mortality and morbidity such as intraventricular hemorrhage (IVH), periventricular leukomalacia (PVL), bronchopulmonary dysplasia (BPD) and bacteriologically confirmed sepsis, assisted ventilation, surfactant administration, intrauterine growth retardation (IUGR), and patent ductus arteriosus (PDA) among very prematurely delivered infants. STUDY DESIGN: Retrospective study of a cohort of 1006 preterm neonates with gestational age ranging from 22 to 32 weeks discharged from the Neonatal Intensive Care Unit (NICU) between 1998 and 2001. Subgroup analysis according to gestational age (GA) (22 to 24, 25 to 28, and 29 to 32 weeks) and plurality (singleton and multiple) was performed using the chi(2) test and an analysis of variance. RESULTS: Of the 1006 infants, 54.3% were white, 21.7% black, 13.7% Hispanic, and 10.3% were classified as Other. Multiple births among white infants were approximately twice that in (42.4%) black infants (22.1%), and was also significantly higher than in the Hispanic (28.3%) and other race/ethnic groups (25.2%). Overall, a higher proportion of black infants were born with a GA 相似文献   

Late second-trimester nonstress test characteristics in preterm delivery before 32 weeks of gestation

OBJECTIVE: To clarify electronic fetal heart rate (FHR) monitoring characteristics in pregnancies with preterm delivery before 32 weeks of gestation, using the late second-trimester nonstress test. METHODS: Among 953 children born from 1993 to 1996, we identified 100 singleton infants born before 32 weeks of gestation in whom second-trimester (24-27 weeks of gestation) electronic fetal monitoring (EFM) records were obtained. Individual components of the FHR patterns [baseline rate, baseline FHR variability, presence of acceleration (at least 10 beats/min for at least 10 s) and periodic or episodic deceleration (at least 25 beats/min for at least 15 s)] and birth characteristics were compared between pregnancy with or without second-trimester decelerations. RESULTS: Among 100 infants, 65 had and 35 did not have second-trimester decelerations. There were no significant differences in gestational age at birth, birth weight, cord arterial blood pH, Apgar score and meconium staining between pregnancies with second-trimester decelerations and those without second-trimester decelerations. There were no significant differences in baseline rate and baseline variability between pregnancies with or without second-trimester decelerations. The number of accelerations in pregnancies with second-trimester decelerations was significantly more frequent than that in pregnancies without second-trimester decelerations (p < 0.001). There was a significant increase in the occurrence of premature rupture of the membranes (PROM; 60.0%) in pregnancies with second-trimester decelerations, when compared with events (37.1%) related to pregnancies without second-trimester decelerations (p < 0.05). There were no significant differences in the onset of breech presentation, cervical incompetency, preeclampsia and abnormal FHR pattern at birth between pregnancies with second-trimester decelerations and those without second-trimester decelerations. Pregnancies with PROM after second-trimester EFM were significantly more likely to have second-trimester decelerations than those without PROM (75.0 vs. 54.2%, p < 0.05). CONCLUSION: Periodic or episodic decelerations during late second-trimester EFM were associated with an increased risk of the occurrence of PROM in pregnancies with preterm delivery before 32 weeks of gestation.     

Uterine blood flow during supine rest and exercise after 28 weeks of gestation

OBJECTIVE: To test the null hypothesis that, after 28 weeks of gestation, uterine blood flow during supine rest and supine exercise is no different than uterine blood flow at left-lateral rest. DESIGN: In vivo experimental study in pregnant women. SETTING: Department of Obstetrics, MetroHealth Medical Center, Cleveland, OH, USA. POPULATION: Fourteen, physically active, late-pregnant women who continued supine exercise throughout gestation. METHODS: Studies were carried out between 29 and 38 weeks of gestation. Maternal blood pressure, maternal heart rate, and ultrasound estimates of volume blood flow in the right ascending branch of the uterine artery were obtained serially at rest in the left-lateral position, at rest in the supine position, during and immediately after 10 minutes of supine exercise, and again at rest in the left-lateral position. Exercise sessions included alternating 60- to 90-second periods of abdominal crunches and leg exercise at moderate/high intensity (Borg's rating of perceived exertion 14 +/- 1). MAIN OUTCOME MEASURES: Blood pressure, heart rate, and uterine artery volume flow. RESULTS: Data are presented as the mean +/- SD. Maternal heart rate and blood pressure were unchanged at supine rest but increased during supine exercise (heart rate increased from 76 +/- 9 to 98 +/- 12 beats per minute, mean arterial pressure increased from 81 +/- 6 to 102 +/- 12 mmHg). Volume flow fell from 410 +/- 93 to 267 +/- 73 cc/minute after 5 minutes of supine rest and then, during supine exercise, increased to 355 +/- 125 cc/minute. Uterine artery luminal diameter and blood flow correlated directly with tissue weights at birth (r(2) values between 0.32 and 0.59). CONCLUSIONS: In physically active women, uterine blood flow decreases during both supine rest and supine exercise but the decrease in the former is twice that seen in the latter.     

Computerised antenatal fetal heart rate recordings between 24 and 28 weeks of gestation

Objective To assess computerised fetal heart rate recordings between 24 and 28 weeks of gestation for gestation related differences.
Design Prospective, cross sectional observational study.
Setting Liverpool Women's Hospital.
Population 112 women: 28 at 27 weeks, 30 at 26 weeks, 27 at 25 weeks and 27 at 24 weeks of gestation, respectively.
Methods Fetal heart recordings of 60 minutes duration were performed once in each pregnancy using the System 8000 fetal heart rate programme (System 8000, Oxford Sonicaid Ltd, Chichester, UK). For each gestational age, records were analysed for short term variation, basal heart rate, accelerations and time spent in high episodes.
Results The mean short term variation increased with gestation (   P =0.05  ). No record had a short term variation <4 msecs. There was no relationship between heart rate and increasing gestation. The mean number of accelerations per record increased with increasing gestation (   P <0.01  ). 20% of recordings showed no accelerations  >15 bpm  . The mean duration spent in episodes of high variation increased with gestation (   P =0.05  ). 13% of recordings showed no time spent in high episodes. All fetuses had normal outcomes at delivery.
Conclusions Absence of episodes of high variation or absence of accelerations is not an abnormal finding at lower gestations. The standard threshold of 4 msecs for short term variation appears to remain valid at lower gestations. These differences should be considered when using computerised CTG analysis at early gestations.     

Perinatal management and problems of preterm twins less than 32 weeks of gestation in Japan

Between 1983 and 1998 there were 23433 births at Kitasato University Hospital, including 359 births. A retrospective analysis was performed on 320 twin pairs analyzing survivability indexes with respect to fetal age, chorionicity and birth weight discordance. Furthermore, the paper illustrates an analysis of causes of neonatal deaths as well as the rate of various complications of twins delivered before 32 weeks gestation such as twin-twin transfusion syndrome and periventricular leukomalacia.     

Elective induction of labor at 39 weeks of gestation: a prospective randomized trial

OBJECTIVE: To clarify the safety of elective induction of labor at 39 weeks of gestation. STUDY DESIGN: Prospective randomized study. SUBJECTS AND METHODS: Uncomplicated nulliparas (N = 194) were randomly assigned at 36 weeks of gestation. Labor was electively induced in 63 women at 39 weeks of gestation in the active management group (I group, N = 98). Spontaneous labor onset was expected with semi-weekly nonstress test (NST) and amniotic fluid index (AFI) by 42 weeks of gestation in the expectant group (E group, N = 96). Perinatal events were compared between the 2 groups. RESULTS: A significantly higher incidence of meconium-stained amnios (19.4% vs 3.2%) and fetal resuscitation (16.7% vs 4.8%) was found in the E group than in the I group. Also, although a significantly higher incidence of epidural analgesia was noted in the I group (89%) than in the E group (54%) (labor onset > or = 39 weeks, N = 72), the duration of the 1st stage was shorter in I group and the duration of the 2nd stage was not significantly different. No other significant difference was noted between the 2 groups in terms of the rate of C-section, blood loss, incidence of pathological FHR, birth weight, Apgar score, umbilical arterial pH, or admission to NICU. CONCLUSION: Active management of labor at 39 weeks could be made as safely as expectant management with modified biophysical profile monitoring.     

Delivery room strategies and outcomes in preterm infants with gestational age 24-28 weeks.

OBJECTIVE: To investigate the effect of different delivery room strategies on survival, short term morbidity, and outcomes in extremely premature infants. METHODS: This retrospective cohort study included all preterm infants with a gestational age between 24 and 28 weeks who were born in 1992-1997 (period A; n = 161) and in 1998-2003 (period B; n = 163). In period A, elective intubation was performed. In period B, if spontaneous breathing was present, nasal continuous positive airway pressure (nCPAP) was applied. RESULTS: Survival rate and the number of never-intubated infants significantly increased in period B. No differences were found concerning short-term morbidity. Among major outcomes, the need for retinopathy of prematurity (ROP) surgery and the length of stay were significantly lower in period B. Subgroup analysis showed no significant differences from period A to period B in infants with gestational age 24-26 weeks. In the 27-28 weeks subgroup, the never-intubated infants rate increased from 2.8% to 21.3% and survival rate increased from 63% to 79%. A reduced need for ROP surgery and a shorter hospital stay were also observed. CONCLUSIONS: Changes in delivery room strategy tending to reduce mechanical ventilation in extremely premature infants are likely to benefit essentially infants of 27-28 weeks of gestation. Extension of such benefits to premature infants at the limit of viability requires further research.     

Gastrointestinal and feeding issues for infants <25 weeks of gestation

Appropriate nutrition is essential for optimal development and growth of preterm infants. Infants less than 25 weeks corrected gestational age are frequently the most difficult group for which to provide adequate nutrition due to minimal energy stores and high fluid losses. Nutrient delivery becomes an integral, but also very challenging part in their management. Early administration of intravenous nutrients provides a critical bridge to full enteral nutrition. However, enteral feeding is challenging due to immaturities of the intestinal tract, feeding intolerance and the risk of catastrophic gastrointestinal disease such as necrotizing enterocolitis (NEC). Decreased gastric acid production, increased gut permeability, reduced immunoglobulins, immature intestinal epithelia and a decreased mucin barrier all contribute to weakness to gastrointestinal insult. This review aims to illustrate the importance of enteral feeding and the common challenges and approaches in the nutrition of infants born at this age.