Birth Weight-specific Neonatal Mortality Research Articles

Improvements in birth weight-specific neonatal mortality rates in the state of Qatar between 2003 & 2010 and a comparative analysis with the Vermont Oxford Network database report of 2007: A pearl study review

Objective:The study aimed to develop a national reference on birth weight-specific neonatal survival in the State of Qatar to facilitate parental counseling.Study Design:This was a retrospective, analytic, and comparative study.Materials and Methods:The birth weight-specific neonatal mortality data for the years 2003 and 2010, collected from the admission and discharge registers of the neonatal intensive care unit, were stratified using the stratifications given in Vermont Oxford Network (VON) 2007 annual report. Category-wise birth weight-specific mortality and relative risk (RR) of death were compared between Qatar data (2003 and 2010) and VON 2007 report.Results:Qatar's neonatal mortality rate (NMR) dropped from 5 of 1000 in 2003 to 4.4 of 1000 in 2010 (P=0.443) which was significant for birth weight categories 501–750 g and 751–1000 g (P=0.026 and P=0.05, respectively). Qatar's NMR in 2010 was significantly lower than VON's NMR during 2007 (P<0.001) though VON's NMR was significantly lower among birth weight categories 751–1000 g and 1001–1500 g (P=0.001 and P=0.003, respectively). The RR of mortality decreased with increasing birth weight. The decline was very sharp for birth weight categories between 500 and 1500g. The RR was 25 times higher in babies with birth weight less than 750 g as compared to babies with birth weight ≥ 2550 g, both in Qatar and VON data. For birth weight categories 751–1000 g and 1001–1500 g, the RR was twice in Qatar as compared to the VON report (16.8 versus 7.8, and 5.5 versus 2.7, respectively).Conclusions:Qatar's current overall and birth weight-specific NMRs are comparable with the VON report except in birth weight categories 751–1000 g and 1001–1500 g which were higher in Qatar. This needs further in-depth qualitative analysis.

A parsimonious explanation for intersecting perinatal mortality curves: understanding the effects of race and of maternal smoking.

BackgroundNeonatal mortality rates among black infants are lower than neonatal mortality rates among white infants at birth weights <3000 g, whereas white infants have a survival advantage at higher birth weights. This finding is also observed when birth weight-specific neonatal mortality rates are compared between infants of smokers and non-smokers. We provide a parsimonious explanation for this paradoxical phenomenon.MethodsWe used data on births in the United States in 1997 after excluding those with a birth weight <500 g or a gestational age <22 weeks. Birth weight- and gestational age-specific perinatal mortality rates were calculated per convention (using total live births at each birth weight/gestational age as the denominator) and also using the fetuses at risk of death at each gestational age.ResultsPerinatal mortality rates (calculated per convention) were lower among blacks than whites at lower birth weights and at preterm gestational ages, while blacks had higher mortality rates at higher birth weights and later gestational ages. With the fetuses-at-risk approach, mortality curves did not intersect; blacks had higher mortality rates at all gestational ages. Increases in birth rates and (especially) growth-restriction rates presaged gestational age-dependent increases in perinatal mortality. Similar findings were obtained in comparisons of smokers versus nonsmokers.ConclusionsFormulating perinatal risk based on the fetuses-at-risk approach solves the intersecting perinatal mortality curves paradox; blacks have higher perinatal mortality rates than whites and smokers have higher perinatal mortality rates than nonsmokers at all gestational ages and birth weights.

Annual summary of vital statistics--2002.

The crude birth rate in 2002 was 13.9 births per 1000 population, the lowest ever reported for the United States. The number of births, the crude birth rate, and the fertility rate (64.8) all declined slightly (by 1% or less) from 2001 to 2002. Fertility rates were highest for Hispanic women (94.0), followed by black (65.4), Asian or Pacific Islander (63.9), Native American (58.0), and non-Hispanic white women (57.5). Fertility rates declined slightly for all race/ethnic groups from 2001 to 2002. The birth rate for teen mothers continued to fall, dropping 5% from 2001 to 2002 to 42.9 births per 1000 women aged 15 to 19 years, another record low. The teen birth rate has fallen 31% since 1991; declines were more rapid for younger teens aged 15 to 17 (40%) than for older teens aged 18 to 19 (23%). The proportion of all births to unmarried women remained approximately the same at one third. Smoking during pregnancy continued to decline; smoking rates were highest among teen mothers. In 2002, 26.1% of births were delivered by cesarean section, up 7% since 2001 and 26% since 1996. The primary cesarean rate has risen 23% since 1996, whereas the rate of vaginal birth after a previous cesarean delivery has fallen 55%. The use of timely prenatal care increased slightly to 83.8% in 2002. From 1990 to 2002, the use of timely prenatal care increased by 6% (to 88.7%) for non-Hispanic white women, by 24% (to 75.2%) for black women, and by 28% (to 76.8%) for Hispanic women, thus narrowing racial disparities. The percentage of preterm births rose to 12.0% in 2002, from 10.6% in 1990 and 9.4% in 1981. Increases were largest for non-Hispanic white women. The percentage of low birth weight (LBW) births also increased to 7.8% in 2002, up from 6.7% in 1984. Twin and triplet/+ birth rates both increased by 3% from 2000 to 2001. Multiple births accounted for 3.2% of all births in 2001. The infant mortality rate (IMR) was 6.9 per 1000 live births (provisional data) in 2002 compared with 6.8 in 2001 (final data). The ratio of the IMR among black infants to that for white infants was 2.5 in 2001, the same as in 2000. Racial differences in infant mortality remain a major public health concern. The role of LBW in infant mortality remains a major issue. New Hampshire, Utah, and Massachusetts had the lowest IMRs. State-by-state differences in IMR reflect racial composition, the percentage of LBW, and birth weight-specific neonatal mortality rates for each state. The United States continues to rank poorly in international comparisons of infant mortality. Expectation of life at birth reached a record high of 77.2 years for all sex and race groups combined in 2001. Death rates in the United States continue to decline. Between 2000 and 2001, death rates declined for the 3 leading causes of death: diseases of the heart, malignant neoplasms, and cerebrovascular diseases. Death rates for children ages 1 to 19 years decreased for unintentional injuries by 3.3% in 2001; the death rate for chronic lower respiratory diseases decreased by 25% in 2001. Cancer and suicide levels did not change for children ages 1 to 19. A large proportion of childhood deaths continue to occur as a result of preventable injuries.

Birthweight-specific neonatal mortality in developing countries and obstetric practices

Objectives: To evaluate birthweight-specific neonatal mortality and perinatal interventions in major medical centers in developed and developing countries. Methods: A survey was developed and electronically mailed to 13 medical centers participating in the Global Network for Perinatal and Reproductive Health (GNPRH). The ability of a center to provide requested data was assessed. The mortality rates and use of specific perinatal interventions in centers in developing countries were compared with developed countries. Results: Nine centers in developing countries responded to the survey, and three centers in developed countries were used for comparison. Data collection was highly variable. Most developing country centers were able to provide data by birthweight but not by gestational age. The differences in mortality rates between developing and developed countries were more pronounced at lower gestational ages and birthweights. A difference was found in perinatal interventions between developing and developed countries. In the former, viability was generally considered 28 weeks, and the gestational age at which cesarean sections were usually performed for the sake of the fetus at preterm gestations varied from 26 to 37 weeks. Most centers did not routinely induce for pPROM; only five out of nine centers used antibiotics to prolong latency. Most centers used tocolysis beginning at 26–28 weeks through 32–37 weeks, and a variety of tocolytic agents were used. Most centers routinely used corticosteroids for preterm infants, and all centers employed repeat weekly steroid dosing if undelivered. Conclusions: Despite the fact that the GNPRH centers included in this study represent some of the best health care available in these countries, they lag far behind centers in developed countries in neonatal mortality rates and their use of various obstetric practices. Furthermore, incomplete and inconsistent data collection complicates the evaluation of the factors contributing to high neonatal mortality rates.

Annual summary of vital statistics: 2000.

The birth rate in 2000 (preliminary data) was 14.8 births per 1000 population, an increase of 2% from 1999 (14.5). The fertility rate, births per 1000 women aged 15 to 44 years, increased 3% to 67.6 in 2000, compared with 65.9 in 1999. The 2000 increases in births and the fertility rate were the third consecutive yearly increases, the largest in many years, halting the steady decline in the number of births and fertility rates in the 1990s. Fertility rates for total white, non-Hispanic white, black, and Native American women each increased about 2% in 2000. The fertility rate for black women, which declined 19% from 1990 to 1996, has changed little since 1996. The rate for Hispanic women rose 4% in 2000 to reach the highest level since 1993. Birth rates for women 30 years or older continued to increase. The proportion of births to unmarried women remained about the same at one third, but the number of births rose 3%. The birth rate for teen mothers declined again for the ninth consecutive year. The use of timely prenatal care (83.2%) remained unchanged in 2000, and was essentially unchanged for non-Hispanic white (88.5%), black (74.2%), and Hispanic (74.4%) mothers. The number and rate of multiple births continued their dramatic rise, but all of the increase was confined to twins; for the first time in more than a decade, the number of triplet and higher-order multiple births declined (4%) between 1998 and 1999 (multiple birth information is not available in preliminary 2000 data). The overall increases in multiple births account, in part, for the lack of improvement in the percentage of low birth weight (LBW) births. LBW remained at 7.6% in 2000. The infant mortality rate (IMR) dropped to 6.9 per 1000 live births (preliminary data) in 2000 (the rate was 7.1 in 1999). The ratio of the IMR among black infants to that for white infants was 2.5 in 2000, the same as in 1999. Racial differences in infant mortality remain a major public health concern. The role of low birth weight in infant mortality remains a major issue. Among all of the states, Utah and Maine had the lowest IMRs. State-by-state differences in IMR reflect racial composition, the percentage LBW, and birth weight-specific neonatal mortality rates for each state. The United States continues to rank poorly in international comparisons of infant mortality. Expectation of life at birth reached a record high of 76.9 years for all gender and race groups combined. Death rates in the United States continue to decline. The age-adjusted death rate for suicide declined 4% between 1999 and 2000; homicide declined 7%. Death rates for children 19 years of age or less declined for 3 of the 5 leading causes in 2000; cancer and suicide levels did not change for children as a group. A large proportion of childhood deaths, however, continue to occur as a result of preventable injuries.

The Effect of Surfactant on Birthweight-Specific Neonatal Mortality Rate, New York City

PURPOSE: Surfactant has been shown to cause decreased neonatal mortality rate (NMR) in randomized studies of preterm infants. It is not clear whether the introduction of surfactant caused a decrease in neonatal mortality in a community. This study explores the hypothesis that the introduction of surfactant in 1990 to 1991 explains a decrease in neonatal mortality in New York City (NYC) among infants with birthweight of 500 to 1499 g. METHODS: For each of the 20 hospitals in New York City that began using surfactant in 1990 or 1991, we compared the NMR in the 2 years before the introduction of surfactant with the NMR in the 2 years after its introduction. Poisson regression models were fit to the death rates, adjusting for birthweight and other determinants of neonatal mortality. RESULTS: NMR in the 20 hospitals decreased by 13.7% (from 231.3 to 199.6 neonatal deaths per 1000 live births). This decrease remained significant after adjusting for birthweight and other risk factors. Infants with birthweight 1000 to 1249 grams benefited most from the introduction of surfactant; their NMR decreased by 19.6%. After adjusting for birthweight, those born before the introduction of surfactant were 1.18 times as likely to die in the first 27 days as those born after the introduction of surfactant (95% CI 1.04, 1.33). CONCLUSION: It appears that surfactant had a significant impact on NMR in NYC among very low birthweight babies.

Neonatal and postneonatal mortality in Germany since unification

BACKGROUNDAfter unification, the gap in infant mortality rates between the two parts of Germany widened until 1996 before converging. The reasons for these changes have not, so far, been apparent.OBJECTIVESTo...

Relationship of cesarean delivery to lower birth weight–specific neonatal mortality in singleton breech infants in the United States

Objective: The preferred route of delivery for breech presentation has been controversial. We compared the birth weight-specific neonatal mortality of vaginal births to cesarean births in singleton births with breech presentation. Methods: A total of 371,692 singleton live births with breech presentation were selected for the study from the United States birth cohorts for the years 1989–1991. Differences in birth weight specific mortality were compared using a z-statistic for differences in proportions and by logistic regression. Results: Compared to primary vaginal births, primary cesarean births had significantly lower neonatal mortality for all birth weight groups, despite increased prevalence of fetal malformations in the cesarean as compared with vaginally delivered group. This mortality difference was greatest in the first hour of life. Difference in overall neonatal (less than 28 days) mortality rate ranged from a low of 1.6-fold in the 500–749 g group (726.6 per 1000 vaginal births compared with 456.3 per 1000 cesarean births, P < .001) to as high as about three-fold in the 1250–1499 g group (232.9 per 1000 vaginal births compared to 72.5 per 1000 cesarean births, P < .001). In the group with birth weights over 2500 g, neonatal mortality in the primary vaginal births was 5.3 per 1000 and in the primary cesarean births, 3.2 per 1000 ( P < .001). Similarly, repeat cesarean births had significantly lower birth weight-specific neonatal mortality, compared with vaginal births after previous cesarean. Conclusion: Singleton live births with breech presentation delivered by cesarean had lower birth weight-specific neonatal mortality as compared with vaginal births.

Relationship of Cesarean Delivery to Lower Birth Weight–Specific Neonatal Mortality in Singleton Breech Infants in the United States

Relationship of Cesarean Delivery to Lower Birth Weight–Specific Neonatal Mortality in Singleton Breech Infants in the United States

Neonatal mortality in the Czech Republic during the transition

Objectives: To identify factors underlying the reduction in neonatal mortality in the Czech Republic during the 1990s and to identify scope for further improvements. Design: Examination of trends in birth weight and birth weight specific neonatal mortality in the Czech Republic and comparison with figures from Sweden, which has one of the lowest neonatal mortality rates in Europe. Setting: The Czech Republic. Subjects: All singleton births occurring in the Czech Republic in 1989–1991 and 1994–1995, with a comparison group of all singleton births in Sweden in 1989–1991. Main outcome measures: Neonatal mortality rate. Results: Despite a slight worsening in the birth weight distribution, the neonatal mortality rate in the Czech Republic fell from 5.6 to 3.8 per thousand live births. This was due to an improvement in the survival of infants at all birth weights but especially amongst the lightest. Eighty percent of the overall improvement was due to greater survival among those under 2500 g. Comparison with Swedish birth weight specific rates indicates that, for the country as a whole, only small additional gains are likely as a result of improved survival at a given birth weight but, instead, a reduction in the proportion of low birth weight babies would have a much greater effect. Regional analysis indicates that the improvements have been much greater in Prague than in the rest of the country. Conclusions: An effective strategy to reduce neonatal mortality in the Czech Republic should have two elements. The first is to address the socio-economic determinants of low birth weight. The second is to reduce regional inequalities in the quality of neonatal care. This should, however, be supplemented by more detailed investigation to identify specific amenable factors.

Structured review of neonatal deaths in a managed care organisation.

We sought to quantify neonatal mortality (< 28 days) in a 10-hospital system, determine what proportion was associated with suboptimal neonatal care and make recommendations on how neonatal mortality rates (NMRs) could be used in quality improvement efforts. Deaths were identified using electronic linkage to the State of California Death Certificate Tapes. Individual fatalities were reviewed by a minimum of two physicians who did not care for the infant. Deaths were classified as either being associated with suboptimal care or not. For deaths where suboptimal care was an issue, emphasis was on delineating the process involved in the death. Subjects were all neonatal deaths among 64,469 babies born in 1990-91 in the 10 birth facilities of the Kaiser Permanente Medical Care Program, Northern California Region. A total of 241 neonatal deaths were identified. Adjusting for prematurity by increasing the follow-up period in preterm babies (included as neonatal deaths if they died up to 40 weeks corrected gestational age + 27.9 days) increased overall mortality rates by 5%. Birthweight-specific NMRs in Kaiser Permanente are similar to those of other published reports. Among the 198 deaths in babies weighing > or = 500 g at birth, only 14 (7%) were possibly associated with suboptimal care. In populations with access to health insurance, reporting only aggregate NMRs is of limited use. The number of deaths that could be ascribed to suboptimal neonatal care is very small and measuring variations in rates of such deaths is difficult. Future measurements of quality of care will require more sophisticated measures, database systems, review strategies and dissemination methods.

Neonatal mortality for very low birth weight deliveries in South Carolina by level of hospital perinatal service

OBJECTIVE: The purpose of this study was to determine whether neonatal mortality rates for very low birth weight (500 to 1499 g) infants born in South Carolina differ by level of perinatal services available at the hospital of birth. STUDY DESIGN: Linked live birth certificates and infant death certificates for 1993 through 1995 were used. Birth weight–specific neonatal mortality rates among 2375 very low birth weight infants were estimated and analyzed by race and by level of perinatal services at the hospital of birth. Rates were compared with χ 2 analysis. RESULTS: Seventy-eight percent of very low birth weight deliveries occurred in level III hospitals. The overall neonatal mortality rate was 178 deaths/1000 very low birth weight live births. Neonatal mortality rates, adjusted for birth weight and race, were significantly higher ( P < .05) for infants born in level I hospitals (267 deaths/1000 live births), all level II hospitals (232 deaths/1000 live births), and level II hospitals with neonatologists (213 deaths/1000 live births) than for infants born in level III centers (146 deaths/1000 live births). CONCLUSION: Very low birth weight infants are more likely to survive if born in level III hospitals than in level I or II facilities, with or without neonatologists. Obstetric providers should support public health efforts and perinatal health systems to ensure that all women have access to a strong system of risk-appropriate perinatal care. (Am J Obstet Gynecol 1998;179:374-81.)

Are differences in birth weight-specific neonatal mortality between racial/ethnic groups explainable by differences in Apgar scores? 1247

Are differences in birth weight-specific neonatal mortality between racial/ethnic groups explainable by differences in Apgar scores? 1247

Mode of delivery influences age-specific, birth weight-specific neonatal mortality in very low birth weight infants. 1194

Effect of delivery mode on neonatal mortality in very low birth weight(VLBW) births has been controversial. We examined this question, using the U.S. Linked Birth/Infant Death Data Sets for three years, 1989-91. Of all VLBW live births (n=141,497), 47.9% were delivered by primary vaginal delivery, 1.5% by vaginal delivery with a history of previous C-section, 37.5% by primary C-section, 7.0% by repeat C-section, and 6.2% by unknown mode of delivery. Only the VLBW (<1,500 gms) live births delivered by primary vaginal delivery or by primary C-section were examined. Neonatal mortality rates (NMR) were expressed by age of death per 1,000 live births for <1hr and <28 days NMR and per 1,000 survivors for 1-23 hrs, 1-6 days, and 7-27 days NMR. In all VLBW groups, births by primary C-section was associated with a significantly lower <1hr NMR, compared to the births by primary vaginal delivery (Table). This difference in <1hr NMR was progressively greater with a decrease in birth weight. The association of low NMR with C-section persisted throughout the entire neonatal period in the 500-749 gm group, but only up to 23 hrs of life in the remaining VLBW groups. Primary C-section was associated with low overall (<28 days) NMR only in the <1,000 gm births and not in the 1,000-1,499 gm group, however.

Birthweight, Preterm Births, and Neonatal Mortality in Belgium and the United States

Buekens, Pierre; Wilcox, Allen J.; Kiely, John; Masuy-Stroobant, Godelieve Author Information

Neonatal intensive care cots: estimating the population based requirement in Trent, UK.

To estimate the population based requirement for neonatal intensive care (NIC) cots by investigating NIC utilisation in a large population based study. This was a two year, non-randomised, prospective cohort study of neonates receiving NIC in hospitals in the Trent Regional Health Authority (RHA). The main study considered the 2979 neonates born to Trent RHA residents who had begun high dependency care in Trent RHA or neighbouring health authorities between 1 April 1990 and 31 March 1992 and met any of the following criteria: (i) birth weight < 1500 g; (ii) gestation < 32 weeks; (iii) need for active respiratory support other than initial resuscitation; (iv) need for in utero or neonatal transfer to receive high dependency care; (v) severe asphyxial brain insult after delivery : and (vi) death. The analysis here is restricted to the 1730 neonates who received total parenteral nutrition or assisted ventilation, or both; that is, those who received NIC level 1 (ICL1) on at least one day. MEASUREMENT AND ANALYSIS: The treatment history of each neonate was converted into a time-line detailing the dates of beginning and stopping NIC, the dates of any transfers between units, and any gaps in NIC treatment. The duration of ICL1 was observed directly and that of intensive care level 2 (ICL20 was imputed from a model based upon round trip transfers. These were also recorded on the timeline. The time-lines were first used to derived the observed distribution of the utilisation of NIC cots in Trent RHA during the study. An extensive series of Monte Carlo simulations was then carried out in order; (i) to estimate cot requirements in smaller populations; (ii) to determine whether Trent RHA utilised its NIC cots in a manner that was clinically appropriate at the population based level; (iii) to perform a series of sensitivity analyses; and (iv) to compare results with an equivalent study carried out in the Northern RHA. Trent RHA is reasonably representative of the greater population of England and Wales in terms of both the distribution of birth weight and of birth weight-specific neonatal mortality. Trent RHA did not seen to be underprovided for NIC cots or to be overusing these cots inappropriately. It therefore seems reasonable, if the assumptions of the analysis are borne carefully in mind, to treat these utilisation data as a rough guide to true population based need. NIC cot requirements depend critically upon the size of the served population - small populations are subject to greater random variability and require relatively more cots to ensure cot availability on an equivalent proportion of days. A neonatal unit should not therefore serve a population generating fewer than 5000 and 25 000 births per annum, the estimated population based provision which would ensure free cots on 29 out of 30 days falls gradually from 1.20 to 0.88 NIC cots per 1000 births per annum. A cooperative network of NICUs offers the opportunity to provide fewer cots per head of population while maintaining good access for most neonates referred to the service.

Which birthweight groups contributed most to the overall reduction in the neonatal mortality rate in the United States from 1960 to 1986?

We determined the relative contributions of individual birthweight groups to the reduction in neonatal mortality rate (NMR) of US singleton livebirths from 1960 to 1986, the period during which neonatal intensive care was introduced and became established. Changes in the NMR for each race (non-white/white) and birthweight group were assessed in terms of three components of NMR (1) birthweight-specific neonatal mortality rate (BWS-NMR), (2) birthweight distribution, and (3) the interaction resulting from simultaneous changes in BWS-NMR and birthweight distribution. Overall, NMR decreased from 16.7 per 1000 livebirths in 1960 to 5.5 per 1000 livebirths in 1986. This reduction was achieved mainly by improvements in the BWS-NMRs of all birthweight groups. Neonates who weighted > 1.5 kg at birth were the major contributors to the overall reduction in the NMR; approximately two-thirds of total reduction in NMR between 1960 and 1980 and 52.6% of the total reduction between 1980 and 1986 occurred in the > 1.5 kg birthweight groups. Our study demonstrates that with the introduction of neonatal intensive care, survival of infants with birthweights > 1.5 kg improved markedly and that this improvement accounted for most of the decline in the neonatal mortality rate in the United States from 1960 to 1986. Therefore, in measuring the effectiveness of neonatal intensive care, the assessment should include not only very low birthweight (< 1.5 kg) but all birthweight groups.

Birthweight‐specific infant mortality risks for native Americans and whites, United States, 1960 and 1984

We used NCHS natality and linked-birth/death certificate tapes to compare birthweight-specific neonatal and postneonatal mortality risks for Native Americans and whites in 1960 and in 1984. The birthweight distributions for the two groups were similar both years. Native American neonatal mortality risk dropped from 20.2 in 1960 to 5.2 in 1984, and the relative risk for Native Americans with respect to whites fell from 1.31 in 1960 to a nonsignificant difference in 1984. Postneonatal mortality risks for Native Americans fell from 27.5 in 1960 to 6.2 in 1984, with a drop in the relative risk from 5.2 to 2.1. Although the relative improvements for Native Americans were highest in postneonatal survival, Native Americans still had over twice the level of white postneonatal mortality. Birthweight was positively associated with survival for both groups, but the odds of Native American neonatal death were affected less by low and very low birthweights. For both groups, improvements in neonatal mortality were highest at the lower birthweights, while the gains in postneonatal survival benefitted normal and high birthweight infants most.

Pregnancy Outcomes of U.S.-born Puerto Ricans: The Role of Maternal Nativity Status

This study examines maternal sociodemographic characteristics, prenatal care use, and birth outcomes of U.S. resident Puerto Ricans by maternal nativity status in order to ascertain if Puerto Rican-born mothers exhibit better birth outcomes than U.S.-born Puerto Rican mothers, after controlling for maternal risk characteristics. All single live births to U.S. resident mothers indicating a Puerto Rican heritage or ethnicity on the infant's Certificate of Live Birth were selected for analysis from the 1983-1986 National Center for Health Statistics' Public Use U.S. Linked Live Birth and Infant Death File. Infants of Puerto Rican-born mothers had a significantly lower risk of low birthweight and small for gestational age infants than infants of U.S.-born Puerto Rican mothers, after controlling for available maternal risk factors. Nevertheless, infants of Puerto Rican-born mothers had a significantly higher risk of neonatal mortality, although they exhibited a significantly lower risk of postneonatal mortality. No significant maternal nativity status differences in very preterm, preterm, very low birthweight, and infant mortality were identified after controlling for the same maternal sociodemographic and prenatal care use variables. Infants of Puerto Rican-born mothers demonstrated higher birthweight-specific neonatal mortality rates but lower birthweight-specific postneonatal mortality rates for nearly every birthweight category. These findings emphasize the need for further investigation of the factors that may influence maternal nativity variations in intrauterine growth retardation, access to tertiary health care services, and postneonatal mortality.

Incidence and Neonatal Mortality of Twins: Italy 1981-90

AbstractThe aims of this study were: 1) to study the characteristics of birth and neonatal mortality (NM) rates of twins as compared to singletons in recent years in Italy; 2) to evaluate NM rate differences among twins and singletons by birthweight: 3) to calculate the cause-specific NM rates among singletons and twins. Data concerning all live-born infants were obtained from the birth and death records of the Italian Institute of Statistics (ISTAT) for the years 1981, 1985, 1989 and 1990 and were analyzed by the Statistics Office of the Italian National Institute of Health. Between 1981 and 1990 the incidence of twins increased from 18.3 to 19.1 per thousand livebirths. This increase was mainly related to twins resulting from multiple pregnancies, thus, the proportion of twins weighing &lt; 1500g also increased from 67 to 77 per thousand. Twins accounted for 10% of overall neonatal mortality in 1981 and 14% in 1990. Between 1981 and 1990 in the Centre-South of Italy the crude NM rates showed a greater decrease among singletons than among twins, while in the North the decrement involved both singletons and twins. The birthweight-specific NM rate showed a steady improvement in survival for twins rather than for singletons in the 1500-2499g weight range. Taking each cause of death in 1989-90, NM rates were considerably higher for twins compared to singletons, Twin mortality risks due to newborn respiratory distress syndrome (RDS) and asphyxia were respectively 11 and 8 times that of singletons. The comparison between twin NM rates in the three geografical areas and in relation to the cause of death indicated a greater incidence of RDS and asphyxia in the Centre-South than in the North.This study offers indications on the planning of perinatal care in order to improve twin survival in the Centre and South of Italy, particularly with regard to the prevention and care of asphyxia-RDS.