Results of the intensive perinatal management of very-low-birth-weight infants (501 to 1,500 grams)

In January 1975 at the University of Colorado Medical Center, a program of intensive intrapartum and neonatal care went into effect for all infants with expected birth weights of over 600 gm. Data are presented on the 187 infants weighing 501 to 1,000 gm born in 1975 to 1976. The 70 infants weighing 501 to 1,000 gm had a perinatal mortality of 65% and a neonatal mortality of 55%. The perinatal mortality of the 117 infants weighing 1,001 to 1,500 gm was 25% and the neonatal mortality 20%. Among the 501- to 1,000-gm infants, cesarean section for delivery of abnormal presentations resulted in a lower perinatal mortality than did vaginal delivery. Apgar scores were predictive of an improved chance of survival, but scores of three or less even at five minutes were associated with a 25% survival rate. Of those infants who did not survive the neonatal period, over 70% had died by 48 hours of life. These results were achieved without the use of beta-mimetic tocolytic agents to inhibit labor or long-acting corticosteroids to enhance pulmonary maturation. The improved survival of the infants weighing 1,500 gm or less when compared with infants of similar weights in preceding years is attributed to more intensive perinatal management of these mothers and their very-low-birth-weight infants.     

Analysis of perinatal mortality at a teaching hospital in Dar es Salaam, Tanzania, 1999-2003

We conducted a retrospective analysis of perinatal mortality at Muhimbili National Hospital (MNH), Dar es Salaam, Tanzania 1999-2003 in order to categorise/classify perinatal deaths as well as to identify key factors in perinatal care that could be improved. Data were retrieved from the MNH obstetric database and causes of early neonatal deaths were traced from the neonatal ward register. The study includes all foetuses weighing =500g. A modified Nordic-Baltic classification was used for classification of perinatal deaths. Over a 5-year period there were 77,815 babies born with a perinatal mortality rate of 124 per 1000 births, 78% of which was labour related stillbirth. The PMR was 913/1000 for singleton births and 723/1000 for multiple births for babies weighing less than 1500 grams and 65/1000 for singleton births and 116/1000 for multiple births for babies weighing 2500 grams or more. Babies weighing less than 1500 grams contributed 26% of PMR, whereas 41% occurred in babies weighing 2500 grams or more. The majority (79%) of neonatal deaths had Apgar score <7 at 5 minutes and the most common causes of neonatal mortality were birth asphyxia (37%) and prematurity (29%). Labour related deaths were more common in multiple pregnancies. The majority of the perinatal deaths should be essentially avoidable through improved quality of intrapartum care. Establishment of perinatal audit at MNH can help identify key actions for improved care.     

Infants born at the threshold of viability in relation to neonatal mortality: Colorado, 1991 to 2003

OBJECTIVE: To determine the contribution of infants born at the threshold of viability (defined as <750 g birth weight) and the role of regionalization of perinatal care on the neonatal mortality rate (NMR) in Colorado. STUDY DESIGN: We performed a retrospective cohort study, evaluating all live births in Colorado from 1991 to 2003, and comparing the periods 1991 to 1996 versus 1997 to 2003. RESULT: The overall unadjusted NMR of the two time periods was 4.3 and 4.4 per 1000 live births, respectively (P=0.42). The contribution of infants with birth weights<750 g to the overall NMR increased from 45.0 to 54.5% (P<0.01). The odds of death for infants<750 g increased between time periods (Odd ratio 1.3, 95% Confidence interval 1.11, 1.61). However, NMR decreased between time periods for all birth weight categories, until infants<600 g. With respect to regionalization, the number of infants<750 g born in a level III care center increased slightly between the two time periods (69.6 versus 73.3%; P=0.04); however, adjusted analysis showed no difference in the practice of regionalization between time periods. Regardless of time period, infants who weighed <750 g born in a level III center had 60% lower mortality risk when compared to <750 g infants born in a non-level III center (P<0.01; 95% CI 0.30, 0.52). CONCLUSION: Despite advances in neonatal medicine, the overall NMR in the state of Colorado remained unchanged between the time periods of 1991 to 1996 and 1997 to 2003. Infants at the threshold of viability continue to have a large impact on the Colorado NMR, making up a larger proportion of overall neonatal deaths. While the results demonstrate that the risk of mortality is significantly reduced for <750 g infants born in a level III center, the practice of regionalization has not changed between the two time periods. Improved efforts to standardize the referral practices to ensure delivery of <750 g infants in level III centers could potentially reduce the impact of these infants on the NMR. While the overall NMR in Colorado has not changed between the two time periods, the NMR for infants>600 g has significantly decreased, suggesting that the boundary delineating the threshold of viability needs reevaluation, as it may have been pushed lower than previously defined.     

Time of birth and the risk of neonatal death

OBJECTIVE: To assess whether mortality is increased in the United States in infants born at night, we compared case-mix adjusted neonatal mortality for low- and high-risk infants born during the daytime (7 am to 6 pm), early night (7 pm to 12 am), and late night (1 am to 6 am). METHODS: California linked birth-death certificate data on 3,363,157 infants, weighing more than 500 g and born without lethal congenital anomalies in 1992-1999, were analyzed. Logistic regression, adjusting for birth weight, gender, prenatal care initiation, maternal hypertension, eclampsia, diabetes, and placental abruption/previa, was used to estimate the relationship between neonatal mortality and time of birth. RESULTS: The overall neonatal mortality was 2.08 deaths per 1,000 live births. Neonatal mortality was 1.88 for daytime births, increasing to 2.37 for early night and 2.31 for late night births. After adjusting for case mix, early night births had a 12% increase and late night births a 16% increase in the odds of neonatal death, an excess that accounts for 9.6% of all neonatal deaths. Mortality was increased for night births that were less than 1,500 g or more than 1,500 g, singletons or multiples, and those delivered vaginally or by cesarean. The increased risk was identified in hospitals that provide intermediate, community, and regional neonatal intensive care, but not in hospitals that provide primary care. CONCLUSION: Identifying the causal factors and reducing the increased burden of mortality for infants born at night should be a major priority for perinatal medicine.     

Perinatal mortality in a large perinatal center: five-year review of 31,000 births

The perinatal mortality rate for 30,928 babies born at Medical Center Hospital, San Antonio, Texas, between 1978 and 1982, was 20.3/1,000 births. Neonatal and fetal mortality rates were, respectively, 10.1/1,000 live births and 10.4/1,000 births. Exclusion of babies who weighed less than 500 gm yielded adjusted fetal, neonatal, and perinatal mortality rates of, respectively, 9.2, 9.8, and 17.9. Birth weight-specific mortality rates were calculated by groups of 250 gm birth weight for all neonates and by increments of 100 gm for babies who weighed 500 to 1,499 gm. Male infants, intrauterine growth-retarded babies, and babies whose mothers were less than 15 years old contributed more deaths than would be expected from the characteristics of the obstetric population. Presumptive cause of fetal death was unknown in 32%, fetal anoxia in 21%, maternal pathologic conditions in 20%, inappropriate fetal growth in 13%, congenital malformations in 8%, and systemic fetal infections in 6%. Leading presumptive causes of neonatal death were immaturity (29%), congenital malformations (18%), hemorrhages (16%), and systemic infections (10%). Hyaline membrane disease and necrotizing enterocolitis contributed, respectively, 7% and 6% of deaths. Past and future trends of perinatal mortality are discussed.     

The dilemma of less than 500 grams birth: epidemiologic considerations

The reporting practice of perinatal data of less than 500 gm is widely inconsistent. This is due mainly to the differences in reporting requirements and ambiguity in the definition of live births, stillbirths and abortions. To evaluate the magnitude a birthweight of less than 500 gm has on a regional perinatal network's vital statistics, we studied race and weight specific data from a cohort of 48,096 births over a 2-year period. One hundred and ten (0.23%) births weighed less than 500 gm, 60 of them were live births occurring at a mean gestation of 22.3 +/- 3 weeks, all of whom died. Blacks had the highest rates for other adverse perinatal outcome measures as well as significantly higher incidence of birthweights less than 500 gm (0.3%), compared to whites and Hispanics, 0.17 and 0.21%, respectively (P less than 0.001). Although they constituted a small fraction of the total births in all ethnic groups, infants weighing less than 500 gm accounted for a significant proportion, 18 and 21%, of the perinatal and neonatal mortality rates (PMR and NMR). These proportions were much higher in the black subgroup. We conclude that major discrepancies in reporting of vital data concerning these infants could affect the vital rates significantly. The effect is not uniform, since the subsets with a high incidence of infants weighing less than 500 gm will have far more variations. This must be considered when comparative epidemiologic studies of perinatal outcome are carried out.     

Low birth weight, intrauterine growth retardation, and preterm delivery

The relationship between low birth weight, intrauterine growth retardation, and preterm delivery in infants born at a perinatal center is described. Between 20% and 30% of infants born weighing 500 to 2000 gm and nearly 50% of infants born weighing 2001 to 2750 gm had intrauterine growth retardation. For infants within the same low-birth weight group, infants with intrauterine growth retardation had one half to one sixth of the neonatal mortality rate of non-growth-retarded infants. However, only in the 501 to 1000 gm group did the difference in mortality between infants with and without intrauterine growth retardation substantially influence the composition of the group of survivors.     

The impact of prenatal care on neonatal deaths in the presence and absence of antenatal high-risk conditions

OBJECTIVE: The purpose of this study was to determine the association between prenatal care in the United States and the neonatal death rate in the presence and absence of antenatal high-risk conditions. STUDY DESIGN: Data were derived from the national perinatal mortality data sets for the years 1995 through 1997, which were provided by the National Center for Health Statistics. Analyses were restricted to singleton live births that occurred after 23 completed weeks of gestation. Multivariable logistic regression analyses were used to adjust for the presence or absence of various antenatal high-risk conditions, maternal age, gestational age at delivery, and birth weight. RESULTS: Of 10,530,608 singleton live births, 18,339 (1.7/1000 births) resulted in neonatal death. Neonatal death rates (per 1000 live births) were higher for African American infants compared with white infants in the presence (2.7 vs 1.5, respectively) and absence (10.7 vs 7.9, respectively) of prenatal care. Lack of prenatal care was associated with an increase in neonatal deaths, which was greater for infants born at > or =36 weeks of gestation (relative risk, 2.1; 95% CI, 1.8, 2.4). Lack of prenatal care was also associated with increased neonatal death rates in the presence of preterm premature rupture of the membranes (relative risk, 1.3; 95% CI, 1.1, 1.5), placenta previa (relative risk, 1.9; 95% CI, 1.2, 2.9), fetal growth restriction (relative risk, 1.7; 95% CI, 1.2, 1.6), and postterm pregnancy (relative risk, 1.4; 95% CI, 1.0, 2.9). CONCLUSION: In the United States, prenatal care is associated with fewer neonatal deaths in black and white infants. This beneficial effect was more pronounced for births that occurred at > or =36 weeks of gestation and in the presence of preterm premature rupture of the membranes, placenta previa, fetal growth restriction, and postterm pregnancy.     

Perinatal Outcome in 41 Sets of Triplets in Jordan

Background: Triplet births, which have increased greatly throughout the world in recent years, have a much greater risk of poor birth outcome than singleton births. The purpose of this study was to determine the perinatal outcome associated with triplet pregnancies and to compare abdominal delivery with vaginal delivery. Methods: We conducted a retrospective study of 41 sets of triplets born between January 1, 1994, and June 30, 1999, at the Princess Badee'a Teaching Hospital in Amman, Jordan. The primary outcome measures were perinatal mortality and early neonatal complications. Results: Of these sets, 21 triplets were delivered vaginally and 20 triplets were delivered by cesarean section. The perinatal mortality rate was 260 per 1000 live births in this series, primarily due to respiratory distress syndrome. The perinatal deaths occurred to infants whose birthweights were primarily 500 to 1500 g (90.6%). Breech presentation was associated with a significantly higher perinatal mortality rate than vertex presentation (62.5% vs 37.5%). Cesarean delivery was associated with a higher perinatal mortality rate than vaginal delivery (30.0% vs 22.2%). Conclusions: These results suggested that cesarean delivery in triplets is not superior to vaginal delivery in terms of fetal and early neonatal outcome. The perinatal mortality rate was significantly higher than that in other recent series due to limited resources in Jordan.     

Diabetes in pregnancy: a population-based study of incidence, referral for care, and perinatal mortality

During 1979 and 1980 in Washington State, 260 infants (live births plus fetal deaths greater than or equal to 20 weeks' gestation) were born to women with preexisting diabetes mellitus, the equivalent to a population-based incidence of 2.1 per 1000 total births. One quarter of these women had non-insulin-dependent diabetes prior to pregnancy. The perinatal mortality rate for all infants of diabetic mothers in this series was 108 per 1000, which was eight times the state perinatal mortality rate. Only 45% of births occurred in the five tertiary centers in the state, whereas 39% occurred in hospitals that had fewer than six deliveries per year complicated by overt diabetes. The mortality rate was slightly, but not significantly, lower among infants born in referral hospitals than among those born in primary-level hospitals. Congenital malformations accounted for 43% of the 28 perinatal deaths, and fetal losses between 20 and 27 weeks' gestation accounted for another 21%. During the 2-year study period there were only three cases in which antepartum care in nonspecialty centers may have contributed to a perinatal loss.     

Breech delivery: evaluation of the method of delivery on perinatal results and maternal morbidity

A retrospective study of 460 single-gestation infants in breech position was conducted at the University of Colorado Medical Center to assess the impact of a policy for the selection of cases for vaginal delivery. Among infants weighing more than 2,500 grams, there was an increase in the cesarean section rate from 13% to 54%, with an associated increase in maternal morbidity from 7% to 15%. This occurred with no significant reduction in adverse perinatal outcome. However, a case-by-case review suggests that more frequent and timely cesarean sections would have further reduced perinatal morbidity and deaths among term infants. Among the infants weighing 2,500 grams or less there was an increase in cesarean births from 5% to 55% following the introduction of the strict criteria for vaginal delivery. Among the infants weighing 1,501 to 2,500 grams there was no significant difference in survival between the cesarean and vaginally delivered patients. Although infants weighing 501 to 1,500 grams delivered by cesarean section survived more frequently than did those delivered vaginally, the differences in perinatal deaths may have been due to a higher birth weight in the cesarean-delivered infants or an over-all improvement in neonatal intensive care for infants of very low birth weight.     

Declining perinatal mortality in Finland between 1987 and 1994: Contribution of different subgroups

Objective: To examine the extent to which the decline in perinatal mortality is attributable to some subgroups, especially to certain birthweight or gestation groups. Study Design: A register study using the Finnish Medical Birth Register for years 1987 to 1994. Results: Of the overall reduction in perinatal mortality from 8.8 to 6.7 per 1000 births, 78% was due to stillbirths, compared with 22% due to early neonatal deaths. The decline in mortality among infants who weighed under 1500 g at birth was the major contributor (62%) to the overall reduction in perinatal mortality. The largest decline in mortality in the stillbirth group occurred among those weighing < 1000 g, while for early neonatal deaths the group most affected weighed 1000-1499 g. A similar pattern emerged when the gestation-week groups were examined. Conclusion: The decline in perinatal mortality is attributable to stillbirths of very low birthweight. The most likely explanations for this result are the improved antenatal and neonatal care and the wider use of malformation screening.     

Perinatal regionalization and neonatal mortality in North Carolina, 1968-1994

OBJECTIVE: Our purpose was to analyze trends across time in the regionalization of low-birth-weight births and time trends for the association between regionalization and decreased neonatal mortality. STUDY DESIGN: Data on 69,452 neonates with birth weights of 500 to 2000 g were obtained from electronic files of birth certificates. Hospitals' perinatal services were classified as level 1, 2, or 3 (level 3 refers to tertiary referral centers). RESULTS: The likelihood of birth outside level 3 hospitals decreased from 1968 to 1994, with an average annual decrease of 24% for infants weighing 500 to 1500 g and 20% for infants weighing 1501 to 2000 g. After 1974, birth in a hospital with level 3 services was associated with a lower risk of dying. The strength of this association increased in the 1990s. CONCLUSIONS: In North Carolina the proportion of infants weighing <2000 g born outside a hospital with level 3 neonatal services declined from 1974 through 1994. After 1974, birth in a hospital with level 3 neonatal services was associated with lower neonatal mortality.     

The Influence of In-Utero Transfer on Perinatal Mortality in a Tertiary Care Centre

From March 1, 1986 through February 28, 1989 inclusive there was a total of 8,319 births with a birth-weight of 500 g or more at Royal North Shore Hospital (RNS). Three hundred and sixty one births (4.3%) resulted from in-utero transfer of high risk pregnancies (IUT); the remainder were booked at RNS. There were 141 perinatal deaths of which 55 (39%) occurred in infants transferred in-utero. For the whole population delivered at RNS the perinatal mortality rate was 17.0/1,000 births (10.8/1,000 for booked patients versus 152.4/1,000 for IUT births), the stillbirth rate was 7.1/1,000 births (5.4/1,000 for booked patients versus 44.3/1,000 for IUT births) and the neonatal mortality rate was 9.9/1,000 livebirths (5.4/1,000 for booked patients versus 113.0/1,000 for IUT livebirths). These data show that crude perinatal mortality statistics from individual hospitals do not necessarily reflect their standard of care. Although the infants transferred in-utero comprised only 4.3% of the total population they constituted more than one third of the perinatal deaths at RNS. Their very high group specific mortality rates are related to their degree of prematurity and associated maternal and neonatal conditions.     

When Do Perinatal Deaths in Multiple Pregnancies Occur?

Perinatal mortality for multiple pregnancy remains at least 5 times the rate for singleton births. The major causes are neonatal deaths due to gross immaturity before 30 weeks' gestation, and stillbirths due to intrauterine growth retardation at all gestations, but especially after 32 weeks. Sixty four per cent of perinatal losses before 30 weeks' gestation occur before 26 weeks, highlighting the need to commence prophylactic measures earlier than usually recommended. The perinatal mortality in infants in multiple births weighing more than 2,500g is the same as that of singletons, but is 10 times this rate in multiple births weighing between 500g and 2,500g. Because the stillbirth rate in twins proceeding beyond 38 weeks' gestation is 3 times that of singleton births, elective termination of pregnancy is recommended if spontaneous labour has not occurred by this time.     

A review of perinatal mortality in an urban situation in a developing country

Perinatal deaths occurring within the City of Harare, Zimbabwe, during 1983 were studied. Data were collected from all known deliveries within the city. This included exact numbers from three central maternity hospitals, and from referring midwife-run maternity clinics. An estimate was made of the number of births and perinatal deaths occurring within the city, but outside these official maternity facilities. All perinatal deaths were reviewed. The birthweight, the cause of death, and the antenatal care registration status of the mother were established. There were 2103 perinatal deaths from an estimated 53,665 total births. Deliveries include 50,138 (93.4%) in hospitals or clinics, 972 (1.8%) before arrival to the maternity service, and an estimated 2555 (4.8%) outside the city maternity services. One thousand seven hundred and fourteen (81.5%) perinatal deaths occurred in hospital or clinic delivered babies, and 134 (6.4%) from babies delivered before arrival at medical services. An estimated 255 (12.1%) of deaths occurred elsewhere. A total of 6380 (12%) patients did not register for antenatal care. There were 909 (43.2%) perinatal deaths in this unregistered group of patients. The overall perinatal mortality rate (PNMR) for infants weighing 500 g or more was 39.2/1000. For registered patients the PNMR was 25.3/1000 and for unregistered patients, 142.5/1000. For infants weighing 1000 grams or more the PNMR was 31.6/1000. The causes of death in the 2103 perinatal deaths were established and classified by clinical cause and by a simple pathological grouping with breakdown by birthweight.(ABSTRACT TRUNCATED AT 250 WORDS)     

Trends in neonatal mortality in Benin City, Nigeria

A total of 18,334 live births and 376 neonatal deaths at the University of Benin Teaching Hospital were analyzed. The neonatal mortality rate has declined significantly from 49.5/1000 in 1974 to 16.4/1000 live births in 1981. The decrease mainly resulted from the reduction of mortality of full size infants (greater than 2500 g) and deaths resulting from perinatal asphyxia. Further reduction may be anticipated if careful attention is paid to the management of breech delivery and if a more intensive care for low birth weight infants is provided.     

Adverse perinatal outcomes among interracial couples in the United States

OBJECTIVE: We examined the association between parental race and stillbirth and adverse perinatal and infant outcomes. METHODS: We conducted a retrospective cohort analysis using the 1995-2001 linked birth and infant death files that are composed of live births and fetal and infant deaths in the United States. The study included singleton births delivered at 20 or more weeks of gestation with a fetus weighing 500 g or more (N = 21,005,786). Parental race was categorized as mother white-father white, mother white-father black, mother black-father white, and mother black-father black. Multivariable logistic regression analysis was performed to examine the association between parental race and risks of stillbirth (at > or = 20 weeks), small for gestational age (defined as birth weight < 5th and < 10th percentile for gestational age), and early neonatal (< 7 days), late neonatal (7-27 days), and postneonatal (28-364 days) mortality. All analyses were adjusted for the confounding effects of maternal age, education, trimester at which prenatal care began, parity, marital status, and smoking during pregnancy. RESULTS: Although risks varied across parental race categories, stillbirth was associated with a higher-than-expected risk for interracial couples: mother white-father black, relative risk (RR) 1.17 (95% confidence interval [CI] 1.10-1.26) and mother black-father white, RR 1.37 (95% CI 1.21-1.54) compared with mother white-father white parents. The RR for stillbirth was even higher among mother black-father black parents (RR 1.67, 95% CI 1.62-1.72). The overall patterns of association for small for gestational age births (< 5th and < 10th percentile) and early neonatal mortality were similar to those seen for stillbirth. CONCLUSION: There is an increased risk of adverse perinatal outcomes for interracial couples, including stillbirth, small for gestational age infants, and neonatal mortality. LEVEL OF EVIDENCE: II-2.     

11. Perinatal mortality

Summary. The perinatal mortality rate in all singleton births was 103 per 1000; 67% of all perinatal deaths were stillbirths and in 77% of stillbirths, intrauterine death had already occurred before admission to hospital. Nine per cent of live births but 40% of stillbirths and 50% of neonatal deaths were of low birthweight (≤2.5 kg). The principal obstetric causes of perinatal deaths were obstructed labour and its consequences, anaemia, antepartum haemorrhage, eclampsia and low fetal birthweight. Nearly half of all perinatal deaths were associated with complicated deliveries of which vaginal breech delivery was by far the most hazardous. Both the proportion of babies with low birthweight and the perinatal mortality rates rose dramatically and progressively with haematocrit <0.30. A raised perinatal mortality rate was also associated with raised haematocrit >0.40. Of the biosocial factors influencing perinatal health, lack of antenatal care, residence outside Zaria, early teenage pregnancy and high parity exerted the most deleterious effect and literacy and antenatal care the most favourable effect on pregnancy outcome.     

Neonatal outcomes and quality of care in level II perinatal centers supported by a children's hospital-medical school level III program.

OBJECTIVE: Eight Level II perinatal centers developed contracts with the children's hospital to provide consultative neonatal patient care, education, and administrative support. The purpose of the present study was to evaluate infant outcomes and quality of care during a 3-year period of the program, 1994 to 1996. STUDY DESIGN: Neonatal mortality rates were determined for the 18,703 live births. Quality of care was assessed for 30 infants who died at the Level II centers and 315 infants transferred to the children's hospital. RESULTS: The neonatal mortality rate was 2.2/1000 live births. Quality-of-care issues primarily involved 80 "drop-in" deliveries 相似文献