Postneonatal mortality in Western Australia 1970-1978

Postneonatal deaths in Western Australia from 1970-78 were studied using a linked file of birth and death registrations. Postneonatal mortality fell during the period under study. The fall occurred in both male and female rates and the former were higher than the latter in all years. The infants at high risk during the postneonatal period were those born to unmarried teenage mothers residing in rural areas, especially if the infants were of low birthweight (less than 2500g). Multiple births and those infants born to mothers whose previous issues were over 4 were also at high risk. Infants born to Aboriginal mothers experienced a significantly higher rate of postneonatal mortality than those born to non-Aboriginal mothers. However, a significant improvement in the Aboriginal rate occurred between 1976 and 1977. The major causes of postneonatal death were sudden infant death syndrome, infections and congenital abnormalities.     

Chemical and physical exposures of parents: effects on human reproduction and offspring

The effect of maternal smoking during pregnancy on birth weight was studied in 12,068 births, the mothers in 1819 of which were regarded as smokers. The children of the smokers were compared with those of controls of similar age, parity, marital status and place of residence. Maternal smoking reduced birth weight in a dose-related manner. Birth weight was least affected among young, primiparous mothers who smoked only slightly, a difference which was, however, entirely caused by those mothers who stopped smoking for the last 3 mth of pregnancy, and this subgroup showed similar figures for postneonatal mortality and morbidity up to the age of 5 to those of their controls. Postneonatal mortality was higher in the total group of the smokers than among their controls, the primiparous or young mothers not differing in this respect from the others. Morbidity up to the age of 5 was significantly higher (P< 0.001) among the children of the smokers, the children of the primiparas and young mothers being affected in a similar way to the others. The low birth weight infants of the smokers had a higher mean birth weight and lower perinatal mortality than the low birth weight infants of the controls, but morbidity up to age of 5 and postneonatal mortality were higher among the smokers in respect of both low birth weight infants and others.     

Sudden infant death syndrome and infant mortality in Aboriginal and non-Aboriginal infants

The aim of this study was to investigate sudden infant death syndrome (SIDS) in the context of total infant mortality for Aboriginal and non-Aboriginal infants. Deaths for infants born in Western Australia from 1980 to 1988 inclusive were ascertained from a total population data base. Infant mortality rates and rates by period and cause of death were calculated for both populations. Aboriginal infants had a mortality rate three times that for non-Aboriginal infants (23.6 cf. 7.9 per 1000 live births) and both populations showed a similar rate of decline in mortality over the study period. There were differences in the proportion of deaths occurring neonatally and postneonatally in the two populations. In terms of SIDS, 21% of the deaths in Aboriginal infants occurred neonatally compared with 7% for non-Aboriginal infants. The overall cause of infant death distribution differed significantly between the two populations ( P < 0.001). During the study period, Aboriginal infants showed a significant increase in deaths due to SIDS and a significant decrease in those due to birth defects and low birthweight. These results suggest it would be useful to review the pathology and diagnosis of sudden unexplained death in infancy.     

Risk status at discharge and cause of death for postneonatal infant deaths: a total population study

OBJECTIVES: To obtain population-based, clinical information regarding potentially modifiable factors contributing to death during the postneonatal period (28 to 364 days), we examined all postneonatal infant deaths in four areas of the United States to determine: (1) the cause of death from clinical and autopsy data rather than vital statistics, (2) whether death occurred during initial hospitalization or after discharge, and (3) the portion of postneonatal mortality attributable to infants who left the hospital with identified high-risk medical conditions. DESIGN AND SETTING: Retrospective medical record review of all postneonatal infant deaths with birth weights greater than 500 g (total N = 386) born to mothers residing in: (1) the city of Boston (1984 and 1985, N = 55), (2) the city of St Louis and contiguous areas (1985 and 1986, N = 123), (3) San Diego County (1985, N = 112), and (4) the state of Maine (1984 and 1985, N = 96). Deaths were identified using linked birth and death vital statistics, and medical record audits of infants' and mothers' charts were performed. Causes of death were obtained from medical record review in conjunction with autopsy if performed (72%, N = 278), medical record alone (17%, N = 67), or vital statistics if no other source was available (11%, N = 41). The medical conditions at the time of discharge for each infant were reviewed and, if judged to confer an increased risk of morbidity or mortality, were classified as high risk. RESULTS: The causes of death were sudden infant death syndrome (47%, N = 181), congenital conditions (20%, N = 77), prematurity-related conditions (11%, N = 43), infections (9%, N = 34), external causes (including injuries, drownings, ingestions, and burns) (7%, N = 25), and other (6%, N = 23). In 24% of congenital and 25% to 44% of prematurity-related deaths, infection was the acute or associated cause of death. Infants born to black mothers were more likely than those born to white mothers to die during the postneonatal period of all major causes of death (7.3 per 1000 vs 3.0 per 1000). Overall, 18% (N = 68) of deaths occurred to infants who never left the hospital; 79% (N = 305) of the infants were discharged before death; and discharge status was unknown in 3% (N = 13). Eighty-one percent of all infants with prematurity-related postneonatal deaths were never discharged, and of the total infants who were initially discharged, only 1% (N = 4) subsequently died of prematurity-related causes. Of all postneonatal deaths, only 16% (N = 62) left the hospital with identified high-risk medical conditions. CONCLUSIONS: These findings suggest that the etiology of postneonatal mortality is heterogeneous, with significant complexity in attributing specific causes of death and making designations of "preventability." The vast majority of infants who died of prematurity-related postneonatal causes never left the hospital, and only a small percentage of all infants that left the hospital before death were identified as being at high medical risk. Therefore, strategies for further decreasing postneonatal mortality must link high-risk follow-up programs to more comprehensive strategies that address risk throughout pregnancy and early childhood.     

Stillbirths, neonatal and post-neonatal mortality by race, birthweight and gestational age

The birthweight and gestational age specific mortality of singleton Aboriginal and White infants born in Western Australia during the period 1980–86 is described. The analyses are based on the approximately 8000 Aboriginal and 143000 White births notified through the Western Australia Midwives' system, which were linked to perinatal and infant death records. Overall, stillbirth, neonatal and post-neonatal mortality risks were significantly higher (P<0.01) for Aboriginals than Whites. However, for specific birthweights and gestational ages, particularly for infants of lower birthweight and shorter gestations, Aboriginals had lower mortality risks than Whites. The ratio of Aboriginal to White mortality risks tended to increase with advancing age of death, suggesting that longer exposure to the well-documented poorer social and environmental conditions of Aboriginal infants increased the mortality risk.     

Perinatal and postneonatal mortality in England and Wales among immigrants from the Indian subcontinent

Perinatal and postneonatal mortality among immigrants to England and Wales from India, Pakistan and Bangladesh (Asians) for the years 1982–85 showed significant differences not only between the immigrant and indigenous populations, but also among the different groups from the Indian subcontinent. Compared with the perinatal mortality rate of 10.1 per 1000 total births in UK born mothers, rates in infants of mothers born in India, Bangladesh, and Pakistan were 12.5, 14.3 and 18.8 respectively. In contrast, postneonatal mortality in infants of Indian and Bangladeshi origin (3.9 and 2.8 per 1000 live births respectively) was lower than in the indigenous population (4.1), with Pakistani infants experiencing the highest rate (6.4). Excess perinatal mortality in infants of Asian origin was apparent at most maternal ages and parities. Pakistani infants had the highest rates of perinatal and postneonatal mortality in all age, parity and birth weight groups. The Asian groups showed higher mortality from congenital anomalies in both the perinatal and the postneonatal period, the rates in Pakistani infants being almost double those in Indian and Bangaladeshi infants. A significant finding was the lower rates of sudden infant death in all the groups of Asian origin.     

Infant death rates among the poor and nonpoor in Kentucky, 1982 to 1983

The mortality rates of infants born in Kentucky during 1982 and 1983 were analyzed to determine whether there were differences between poor and nonpoor infants. We used computer matching with the Social Insurance Food Stamp files and with the Aid for Families With Dependent Children files to define poor and nonpoor Kentucky resident families. The crude death rate for poor infants was 13.7/1,000 births, and the nonpoor death rate was 10.8/1,000 births. After adjusting for several important variables, we found that the poor infant was at a significantly greater risk for death than the nonpoor infant but only during the postneonatal period (relative risk 2.04, P = .0003). Some differences by sex and race were noted. Sudden infant death syndrome and infections were largely responsible for the poor infants' higher postneonatal mortality risk.     

Postnatal age at time of death in infants born at 24-32 weeks'gestation

Abstract Medical records of all 483 infants live-born at 24-32 weeks'gestation in our hospital during the years 1982-86 were reviewed in order to determine postnatal age at time of death for those who died in the first year after birth. Twenty-seven died from immaturity without receiving intensive care and 11 died from lethal congenital malformations. Eighty (18%) of the remaining 445 who received intensive care died: 31% on day 1, 45% on days 2-7, 12% on days 8-28 and 11% on days 29-365. The neonatal mortality rate for those receiving intensive care was 160/1000, and the postneonatal mortality rate was 20/1000.
Delayed mortality was most common in infants of 26-27 weeks'gestation, with 20% (five) of their deaths occurring after 28 days. In each gestational age range, the majority of hospital admission days were occupied by survivors (24-25 weeks = 62%; 26-27 weeks = 91%; 28-29 weeks = 91%; 30-32 weeks = 99%) rather than non-survivors.
Whilst postneonatal mortality is a significant concern, these data suggest that if infants born at less than 33 weeks'gestation are offered intensive care and survive the early neonatal period, the long-term outcome is more likely to be survival rather than delayed death. Furthermore, the majority of hospital admission days invested in such infants involves those who will be discharged home rather than those who will not.     

Differences in infant mortality by race, nativity status, and other maternal characteristics

The objective of this study was to examine the effects of nativity status (native vs foreign born) and other maternal characteristics (age, parity, education, and marital status) on infant, neonatal, and postneonatal mortality among white and black mothers. The design of this nonrandomized cohort study was based on birth and death certificates. The setting involved live births among US residents (excluding California, Texas, and Washington) in 1983 and 1984. The participants included white mothers with 4.4 million births and black mothers with 926,000 births in single deliveries. There were no interventions. With regard to measurements (the main results), after adjusting for other risk factors, neonatal mortality risk was 22% lower among the black foreign-born mothers than among the black native-born mothers, while among white infants, there was no risk difference by nativity. Relative risks were more similar for postneonatal mortality, ie, 24% lower among black foreign-born mothers and 20% lower among white foreign-born mothers. Combining the several categories of risk factors into three broad maternal risk groups, there was a near-doubling of black and near-tripling of white infant mortality rates between the low and high levels of maternal risk. We concluded that if the infant mortality rate in the low-risk groups could be achieved by the moderate- and high-risk groups, there would be a 30% reduction in infant deaths within each race. Since the black infant mortality rate is twice the white infant mortality rate and black foreign-born mothers have much lower rates than black native-born mothers, it is likely that further improvement is possible among black infants.     

Infant mortality among moderately low birth weight infants in Alabama, 1980 to 1983

A previous study of postneonatal deaths among normal birth weight infants in Alabama indicated that rural residence increased the risk of postneonatal death, the magnitude of the excess risk in the black population, and the risk of death from preventable causes. To determine whether this pattern persisted in a group presumably at higher than usual risk of infant death, patterns of mortality among infants weighing 1500 to 2499 g at birth and born in Alabama between 1980 and 1983 were examined by race, residence, and cause of death. Neonatal and infant mortality rates were higher for black infants; postneonatal mortality rates were higher for black infants. Neonatal mortality was highest for white infants from the rural part of the state; post-neonatal mortality was highest for black infants from the rural part of the state. There was little variation in the proportion of preventable postneonatal deaths by race or residence (17.6% for all) but almost twice as many white deaths were not preventable as black ones (39.0 vs 21.9%). It is posited that rural residence may actually be a surrogate measure for lack of access to health services.     

High postneonatal mortality of infants in North Rhine Westphalia

Infant mortality in North-Rhine Westphalia was increased above the national average throughout the postwar period until today. To clarify the underlying causes the official death certificates of infants who died during their first year were linked to their respective birth certificates. Thus, the amount of data about each individual case was increased considerably. The information collected was then evaluated. An especially high mortality was associated with the maternal risk factors illegitimacy, age below 20 and Turkish nationality. Perinatal mortality was high in the groups of Turkish nationals, and unmarried mothers. Socially underprivileged groups on the whole proved to contribute a high amount of postneonatal mortality. Predominant causes of postneonatal mortality were infections, injuries and the diagnosis "sudden infant death syndrome".     

Infant mortality in a region of Finland, 1968–1982

Infant mortality in a region of Finland with about 450000 people and 5400 annual births was examined during a 15-year period, 1968–1982. Total infant mortality declined from 15.8 per 1000 live births in 1968 to 5.0 in 1982. The lowering of neonatal mortality accounted for the decline, as postneonatal mortality remained at the same level throughout the study period. Despite a decrease of nearly 80%, perinatal disorders remained the leading category of primary causes of death. Mortality from congenital malformations decreased by 50%, mortality from sudden infant death syndrome increased from 0.2 to 0.9 per 1000 live births while mortality from accidents, infectious diseases and other diseases remained minor causes of death with no change in frequency. In the low birth weight category, postponement of deaths from early to late neonatal and postneonatal periods occurred, but total infant mortality in the low birth weight category declined by about 60%. During the last two 3-year periods, decrease in birth weight-specific infant mortality was found in the 500–999 g and >2500 g categories. The reasonably high standard of living, good educational level of mothers, well organized primary maternal and child health services and the rapid advances in obstetric and neonatal care equally available and regionalized, have contributed to the favourable progress in infant mortality in Finland.     

Prenatal exposure to cigarette smoking is associated with a decrease in arousal in infants.

OBJECTIVE: Sudden infant death syndrome has been related to both exposure to prenatal cigarette smoke and impaired arousability from sleep. We evaluated whether healthy infants born to mothers who smoked during pregnancy had higher auditory arousal thresholds than those born to mothers who did not smoke and whether the effects of smoking occurred before birth. STUDY DESIGN: Twenty-six newborns were studied with polygraphic recordings for 1 night: 13 were born to mothers who did not smoke, and 13 were born to mothers who smoked (>9 cigarettes per day). Other infants with a median postnatal age of 12 weeks were also studied, 21 born to nonsmoking mothers and 21 born to smoking mothers. White noise of increasing intensity was administered during rapid eye movement sleep to evaluate arousal and awakening thresholds. RESULTS: More intense auditory stimuli were needed to induce arousals in newborns (P =.002) and infants (P =. 044) of smokers than in infants of nonsmokers. Behavioral awakening occurred significantly less frequently in the newborns of smokers (P =.002) than of nonsmokers. CONCLUSIONS: Newborns and infants born to smoking mothers had higher arousal thresholds to auditory challenges than those born to nonsmoking mothers. The impact of exposure to cigarette smoke occurred before birth.     

Is the higher postneonatal mortality in lower social status groups due to SIDS?

In order to study the influence of sociodemographic factors, postneonatal mortality of all live births surviving the neonatal period registered in the Norwegian Medical Birth Registry in 1978–1982 were examined (n = 209 030). Postneonatal deaths (n = 634) were divided into two categories; deaths due to the sudden infant death syndrom (SIDS) (n = 359) and deaths due to other causes (non-SIDS) (n = 275). SIDS and non-SIDS deaths showed different relationships to sociodemographic factors, and the associations appeared to be different for first-born and later born children. SIDS mortality was highest for first-born offspring when the mother was young (adjusted relative risks (RR) 2.3) and had a low educational level (adjusted RR 4.9). For later-born offspring no association between maternal educational level and SIDS was found, while young maternal age (adjusted RR 4.4) and unmarried status (adjusted RR 2.3) were closely associated with SIDS. In the multivariate model, however, there were no statistically significant associations between non-SIDS and sociodemographic factors for firstborn or later-born children. Thus it appears that the increased postneonatal mortality in lower social groups can be explained by an association with SIDS.     

Perinatal Mortality in a Saudi Maternity Hospital

ABSTRACT. Perinatal mortality was analyzed in infants to mothers who delivered at the main Maternity hospital in Riyadh and who represented a large proportion of the obstetric population in the city. The crude perinatal mortality rate was 39.8 per 1000 births. The hirth weight-specific mortality rates were compared with the corresponding Swedish rates. The ratio between the birth weight-specific mortality rates in Riyad and Sweden increased from the lightest to the heaviest hirth weight category. Thus the perinatal mortality rate was 2.3 times higher in infants less than 1500 g, and 8.8 times higher in infants with birth weights of 3500 g and more. Similarly, the ratio between the gestational age-specific mortality rates in Riyadh and Sweden increased with advancing gestational age. The perinatal mortality rate of infants less than 28 weeks was 1.6 times higher, and that of term infants 4.8 times higher than in Sweden. The findings indicated shortcomings in the obstetric services. The perinatal mortality rate of teenage mothers, who comprised 17 percent of the material, was 9.1 times the Swedish rate. Other risk groups were para 0 mothers and mothers with a previous infant loss.     

Postnatal age at time of death in infants born at 24-32 weeks' gestation

Medical records of all 483 infants live-born at 24-32 weeks' gestation in our hospital during the years 1982-86 were reviewed in order to determine postnatal age at time of death for those who died in the first year after birth. Twenty-seven died from immaturity without receiving intensive care and 11 died from lethal congenital malformations. Eighty (18%) of the remaining 445 who received intensive care died: 31% on day 1, 45% on days 2-7, 12% on days 8-28 and 11% on days 29-365. The neonatal mortality rate for those receiving intensive care was 160/1000, and the postneonatal mortality rate was 20/1000. Delayed mortality was most common in infants of 26-27 weeks' gestation, with 20% (five) of their deaths occurring after 28 days. In each gestational age range, the majority of hospital admission days were occupied by survivors (24-25 weeks = 62%; 26-27 weeks = 91%; 28-29 weeks = 91%; 30-32 weeks = 99%) rather than non-survivors. Whilst postneonatal mortality is a significant concern, these data suggest that if infants born at less than 33 weeks' gestation are offered intensive care and survive the early neonatal period, the long-term outcome is more likely to be survival rather than delayed death. Furthermore, the majority of hospital admission days invested in such infants involves those who will be discharged home rather than those who will not.     

Ethnic differences in incidence of sudden infant death syndrome in Birmingham.

Among the 45,204 live births in Birmingham in the three calendar years 1981-3, there were 218 postneonatal deaths, giving a postneonatal mortality rate of 4.82 per 1000 live births. Postneonatal mortality rates were 4.22 for whites, 5.91 for Asians (relative risk 1.26, 95% confidence interval (CI) 1.04 to 1.53) and 8.20 for Afro-Caribbeans (relative risk 1.78, 95% CI 1.25 to 2.55). Among Asians malformations were common (3.36) and sudden infant death syndrome rare (1.18), in contrast to Afro-Caribbeans among whom the rates were 0.66 and 5.25, respectively. Logistic regression analysis demonstrated a significantly lower risk of sudden infant death syndrome (SIDS) in Asians and significantly raised risks of SIDS in very low birthweight babies and those with unemployed parent(s). Ethnic differences persisted after controlling for maternal age, social class, and birth weight. Studies of sociocultural differences in child rearing practices are needed and may uncover important aetiological factors of sudden infant death syndrome.     

Medical care and preterm infants of normal birth weight

Preterm infants of normal birth weight (born before 37 completed weeks of gestation and weighing more than 2,250 g) experience a neonatal mortality risk almost four times higher than do term infants in the same weight range. In an analysis of the effect of hospital level of birth on neonatal mortality, such preterm normal weight infants were found to experience higher mortality if born outside of a Level 3 (tertiary care) center. For all singleton infants in this weight-gestation category born in New York City maternity services during a 3-year period (N = 23,257), the relative mortality risk for Level 1 births (compared with Level 3) was 1.72 (P less than .01) and for Level 2 births 1.47 (P less than .05). The excess mortality at Level 1 and Level 2 units was almost entirely due to a more than twofold higher death rate in black infants born in these units. Several potentially confounding socioeconomic, demographic, and biologic variables entered into a logistic regression model could not account for the higher mortality rates for black infants born in Level 1 and Level 2 units. Among black infants born at Level 1 units, deaths in preterm normal birth weight infants were less likely to occur in a receiving tertiary care center than were either deaths in low birth weight infants or deaths in term normal weight infants, suggesting that the need for special care of preterm normal birth weight infants is underestimated in some hospitals without newborn intensive care units.     

The choice of place of delivery. Effect of hospital level on mortality in all singleton births in New York City

In an analysis of all singleton births and neonatal deaths with known birth weights and gestational ages in New York City maternity services during a three-year period (1976 to 1978), intensive care services at the hospital of birth were found to influence mortality only in preterm (less than 37 weeks' gestation) or low-birth-weight infants (less than 2251 g). By contrast, for infants who were born at term and of normal birth weight, mortality rates did not differ by level of perinatal care available at the hospital of birth. On the average, preterm and low-birth-weight infants were at a 24% higher risk of death if birth occurred outside of a level 3 center, regardless of whether birth occurred at a level 1 or level 2 hospital. Preterm and low-birth-weight infants, though constituting only 12% of births, accounted for 70% of neonatal deaths in New York City. The remaining infants, ie, those born at term and of normal birth weight, who experienced no measurable mortality advantage when born in a level 3 hospital, accounted for 88% of all births.     

Postneonatal mortality among normal birth weight infants in Alabama, 1980 to 1983

To identify reasons for the racial differential in postneonatal deaths and possible intervention strategies, Alabama's linked birth-death file was used to evaluate causes of postneonatal mortality for the 1980 to 1983 cohorts of normal birth weight infants. Causes were aggregated into six categories, and cause-specific rates were compared by race and by urban-rural residence. Both total and cause-specific postneonatal mortality rates among black infants were two or more times higher than for white infants, except for congenital anomalies. The greatest differential was for infection-related deaths. Rural residence increased both the risk of postneonatal death and the magnitude of the racial differential. The risks were especially elevated for deaths due to infection and "systemic causes" (including those in the perinatal category). Only 26% of postneonatal deaths were probably not preventable, and nearly one third were clearly preventable. Potential prevention strategies include injury control, prevention of infectious diseases, and prompt treatment of infectious diseases.