Mother's social class and perinatal problems in a low-problem area

This study reports the variation in perinatal problems related to social class in one area in Finland. Data on length of gestation, birthweight, one-minute Apgar score, and need for special care in relation to social class were obtained from a large clinical trial (n = 2912) on iron prophylaxis during pregnancy. Social class was determined from the woman's own occupation and education. Occupation was obtained from the women themselves and classified as upper white collar, lower white collar I, lower white collar II, and workers; entrepreneurs, students and women with no information were excluded. Education was obtained by record linkage to the national education register, and all women were classified by the years normally required to attain a certain level: greater than or equal to 13, 12, 10-11, and less than or equal to 9 years of education. Adjusted for age and parity, a week U-shaped curve was found for gestation length and birthweight, best results being found for the women in the second highest social class. The lower the social class, the more infants with poor Apgar scores. As potential intervening variables we studied marital status, pre-pregnancy weight, smoking, and haematocrit in the 28th week of pregnancy. Their inclusion in multivariate analyses influenced only slightly the differences in perinatal problems between the groups. Our results suggest that in Finland there are still differences in perinatal problems between social classes, but that the relationship is not always linear.     

Pregnancy outcome,infant mortality and mother's education in Piedmont from 1980 to 1995

The paper describes 1980-1995 trends in social differences in reproductive outcomes and infant mortality in Piedmont, Italy. By means of a logistic model, risk differences by mothers'educational level were calculated for low birthweight, stillbirth, neonatal, postneonatal and infant mortality in four time periods (1980-83, 1984-87, 1988-91, 1992-95). Odds ratios of low birthweight for children born to mothers in the lowest educational class compared to the highest are slightly increasing (from 1.43 to 1.57), while those between highest and intermediate educational groups are small and steady. After adjustment for selected confounding variables, for which data were available, these differences are confirmed. Differences in risk for neonatal mortality between highest and intermediate educational groups have strongly reduced from the beginning of the Nineties, while they have increased between highest and lowest classes. Adjusting for birthweight, differences disappear. Postneonatal mortality is strongly related to low educational level and differences are widening: OR for lowest educational level has increased from 1.96 to 2.60. Even within a fairly good health system, social differences are present. Hospital assistance has always been equitable to all new-borns; social differences generate in the environment where pregnant women and infants live. Due to the high attributable risk on infant mortality, reduction in social differences in low birthweight should be considered a priority in public health policy in Piedmont.     

Reinterpreting the effects of maternal smoking on infant birthweight and perinatal mortality: a multivariate approach to birthweight standardization.

Infants of women who smoke during pregnancy have lower birthweights and have been observed to have higher rates of perinatal mortality than infants of non-smokers. It is not clear whether this increased risk of mortality is due to an excess of small births among smokers or to an independent effect of smoking. Although infants of smokers have overall higher mortality rates than non-smokers, low birthweight (< 2500 g) infants of smokers have lower mortality rates than low birthweight infants of non-smokers. However, comparison of birthweight-specific mortality between two groups is problematic when there are differences in the birthweight distributions. Methods that have been developed to standardize for these differences by comparing mortality rates relative to their own mean do not allow for simultaneous control of confounding variables. Using data from over 13,000 births of women who participated in a prepaid health care plan we present a method to standardize for birthweight while adjusting for variables that may confound the relationship between maternal smoking and perinatal mortality. After controlling for race, maternal age, education, parity, and number of cigarettes smoked, we found that 85% of the increased mortality due to smoking was attributable to an excess of small births in the birthweight distribution of offspring of smoking mothers, while 15% was due to higher birthweight-specific mortality at almost all standardized birthweights. Contrary to previous reports, we found that low birthweight infants of smoking mothers are at higher risk of perinatal mortality if a population-specific standard for birthweight is used.     

Maternal education as a modifier of the association between low birthweight and infant mortality

Both low birthweight (LBW) and infant mortality rate (IMR) have been consistently shown to be associated with maternal level of educational attainment. This paper examines the mortality risk attributable to LBW in different levels of maternal education. Comprising the study population were 18,715 singleton live births to Jewish mothers ages 20-39, during the years 1977-1980 in the Negev (the southern part of Israel). Data were obtained from a linked record of birth and death certificates. As expected, proportions of LBW (less than 2500 grams) were inversely related to level of maternal education (12.2% in the lowest educational level, 7.9% and 8.0% in the two intermediate levels, and 7.2% in the highest educational level). The mortality risk attributed to LBW was found to be modified by maternal level of education. Mortality ratios standardized for maternal age and parity were computed, using educational level 3, where the lowest mortality rates were observed, as the standard population. Among LBW infants no significant differences were found across educational levels, except for the lowest educational level where only 69% of the expected number of deaths were observed. The survival advantage of LBW infants in the lowest educational level was observed both in the neonatal and the postneonatal periods. Among normal birthweight (NBW) infants, a statistically significant excess mortality was detected both in the highest and the lowest educational levels. The excess mortality of NBW infants in the highest level of maternal education was due to neonatal mortality (SMR = 2.2), while the excess mortality in this birthweight category in the lowest educational level occur mainly in the postneonatal period (SMR = 2.4).(ABSTRACT TRUNCATED AT 250 WORDS)     

The heavier the better? Birthweight and perinatal mortality in different ethnic groups

BACKGROUND: Mother's ethnicity is associated with her baby's birthweight and risk of perinatal mortality. Given the close relation between birthweight and perinatal mortality, we explored whether ethnic differences in birthweight explain ethnic differences in perinatal mortality. METHODS: Data on all births to mothers born in Norway (808 658), Pakistan (6854), Vietnam (3283) and North Africa (1461) from 1980 to 1995 were obtained from the Medical Birth Registry of Norway. The associations between birthweight and perinatal mortality among ethnic groups were analysed using univariate and multivariate methods. RESULTS: Mean birthweights were low for Vietnamese and Pakistani mothers (3202 g, 3244 g) and high for Norwegian and North African mothers (3530 g, 3559 g). Mean birthweights were largely unrelated to perinatal mortality, which was lowest for Vietnamese (8.2/1000, 95% CI: 5.1-11.3) and highest for Pakistanis (14.9/1000, 95% CI: 12.0-17.7). Intermediate perinatal mortality rates were found among Norwegians (9.5/1000, 95% CI: 9.3-9.7) and North Africans (9.6/1000, 95% CI: 4.6-14.6). Further comparison of weight-specific mortality rates between the two largest ethnic groups showed the low birthweight paradox, where among low-weight births, perinatal mortality was lower among Pakistani than among Norwegian babies. However, adjustment to a relative birthweight scale (units of standard deviations from population-specific mean value) revealed higher rates of weight-specific mortality among Pakistanis across the entire range of birthweights. Multivariate adjustment for relative birthweight and other factors did not change these results. CONCLUSIONS: Differences in perinatal mortality between the ethnic groups were not explained by differences in mean birthweight. Paradoxical differences in birthweight-specific mortality rates could be resolved by adjustment to a relative scale.     

Social class differences in health until the age of seven years among the Finnish 1987 birth cohort

Studies on social class differences in childhood health are controversial partly because of different data collection methods, limited sample sizes and the use of limited numbers of health indicators. The increasing collection of health register data enables the use of such data in social class studies. Our purpose was to investigate social class differences in mortality and morbidity among all children born in Finland in 1987 (N=59,865 liveborns) until the age of seven by using several national health registers, and to study whether perinatal health explains these differences. The follow-up was based on data linkage with six national health registers, with 18 regional registers of mentally disabled children, covering the whole country, and with 38 educational registers of the largest county. Morbidity was measured in terms of a cumulative disease index, the cumulative incidence of asthma, diabetes, epilepsy and intellectual disability, hospitalisations, disease-related welfare benefits and special education. Social class, divided in four groups (I–III, Others) was defined by using the mother's occupation at the time the child was seven years old. Our study showed that register-based data collection is a feasible method for studying social class differences in health. In the unadjusted analysis, social class differences were found for all indicators except mortality after the age of one year and for the cumulative incidence of asthma and diabetes. After adjusting for confounders, the children in the lowest social class had the highest risk for poor health outcome both in the perinatal period and in childhood, and had the most intellectual disabilities, the highest mean of hospitalisation days, and received the most special education. The differences were not explained by perinatal health. The health of the children in the lowest social class was poorer, especially regarding mental indicators.     

Social inequalities in perinatal mortality in a Southern European city

The objective of this study was to describe and explain inequalities in perinatal mortality by educational level and occupational social class in Barcelona for the years 1993–1997. This was a case–control study. Cases were singleton perinatal deaths, controls were singleton live births obtained from a 2% random sample of births. The association among educational level, social class, other confounding and explanatory variables and perinatal mortality was studied through crude and adjusted odds ratios (OR) obtained by logistic regression. The study comprised 423 cases and 1032 controls. The model with mother's age and educational level showed that women with primary education had an OR of 1.75 (95% CI: 1.26–2.42), this association disappearing when explanatory variables were included. We also found inequalities by educational level in fetal mortality. These results point out the need to improve the living conditions, behavioural factors and also the management of pregnancy, labour and the health care of the newborn of these mothers with greater risk.     

Low birthweight, preterm, and small for gestational age babies in Scotland, 1981-1984.

STUDY OBJECTIVE--The aim was to examine the effect of maternal age, gravidity, marital status, previous perinatal deaths, and parental social class on babies born low birthweight, preterm, and small for gestational age. DESIGN--The study used data on discharge summaries from all maternity hospitals in Scotland. SETTING--The study was based on all singleton deliveries in Scotland. PARTICIPANTS--The analysis involved information on 259,462 singleton babies born during the four years 1981-84 in Scotland. MEASUREMENTS AND MAIN RESULTS--Previous perinatal death was found to be the strongest predictor for both preterm and low birthweight. Single mothers were at particularly high risk of having a small for gestational age baby and those who were previously married of having a preterm baby. Women aged less than 20 years old, those over 34 years old, nulligravidae, and those of parity 3 or more were also at increased risk of adverse pregnancy outcome. Mothers and fathers in manual social classes and those who could not be assigned a social class on the basis of their occupation were at increased risk for all three adverse outcomes studied. The babies of parents who were in manual occupations were twice as likely as those of parents in non-manual occupations to be small for gestational age and almost twice as likely to be low birthweight. CONCLUSIONS--Mother's social class is a risk factor for adverse pregnancy outcome independent of maternal age, parity, and adverse reproductive history, and also independent of father's social class. Information on both parents' occupations should be collected in maternity discharge systems.     

Maternal Education and Perinatal Outcomes Among Spanish Women Residing in Southern Spain (2001–2011)

Evidence suggests that educational differences in perinatal outcomes have increased in some countries (Eastern Europe) while remained stable in others (Scandinavian countries). However, less is known about the experience of Southern Europe. This study aims to evaluate the association between maternal education and perinatal outcomes derived from birthweight (low birthweight and macrosomia) and gestational age (pre-term and post-term births) among Spaniards living in the Autonomous Community of Andalusia during the period 2001–2011 (around 19 % of births in Spain); and to evaluate whether the educational differences narrowed or widened during that period, which includes both an economic boom (2001–2008) and the global economic crisis (2009–2011). This study uses the Andalusian Population Longitudinal Database and the Vital Statistics Data provided by the Spanish National Statistics Institute. We study live and singleton births of Spanish mothers who lived in Andalusia at the time of delivery (n = 404,951). ORs with 95 % confidence intervals (crude and adjusted) were estimated using multinomial regression models. A negative educational gradient is observed in all perinatal outcomes studied (i.e., the higher the educational status, the lower the risk of negative perinatal outcomes). However, when disaggregating the sample in two periods, the gradient is only statistically significant for pre-term birth during 2001–2008, while a full gradient is observed in all perinatal indicators in the period 2009–2011 with an increase in the educational inequalities in macrosomia and post-term. Further studies are needed in order to confirm whether there is a causal association between the widening of the educational differences in perinatal outcomes and the onset of the economic crisis in Spain, or the widening can be explained by other factors, such as changes in childbearing patterns and the composition of women accessing motherhood.     

Maternal predictors of perinatal mortality: the role of birthweight.

BACKGROUND: Many maternal characteristics increase the risk for perinatal death. To locate potential sites for intervention, it is important to identify these risk factors and examine how much of the excess mortality is explained by infants' low birthweight. METHODS: Data on all newborns in Finland born between 1991 and 1993 (N = 199,291, of which 1461 were perinatal deaths) were obtained from the Medical Birth Register. Logistic regression analysis was used to adjust for background variables, both including and excluding infants' birthweight. The percentage reduction in odds ratios after adjustment for infants' birthweight was used to estimate the contribution of infants' low birthweight to the excess mortality. RESULTS: After adjusting confounding factors, increased risk for perinatal death was found for eight maternal characteristics. In the following the increased risk is given as odds ratios and the proportions of the excess mortality explained by infants' low birthweight are in parentheses: in-vitro fertilization 4.12 (> 100%); earlier stillbirth 3.43 (87%); higher maternal age, from 1.21 to 3.08 (38-99%); maternal diabetes 2.87 (50%); lower socioeconomic status, from 1.30 to 1.70 (27-44%); smoking during pregnancy 1.45 (> 100%); single mother 1.44 (50%); first birth 1.36 (75%). CONCLUSIONS: Excess mortality due to maternal risk factors occurred mainly through their tendency to cause low birthweight. However, the excess mortality associated with low socioeconomic status, single motherhood, and diabetes was mediated by other mechanisms in addition to low birthweight.     

Perinatal mortality in Scotland: 1970-9.

An examination of the recent decline in perinatal mortality in Scotland during the 1970s showed that despite substantial changes in fertility and the demographic pattern of births, differences in the age, parity, and social class composition of the obstetric population in this decade accounted for just 7% of the overall improvement in perinatal mortality between 1970 and 1979. The general pattern of relative risks associated with maternal age, parity, and social class remained largely unchanged. Marginal changes in the birthweight distribution, however, were sufficient to account for 13% of the reduction in perinatal mortality. The low birthweight infant, especially those weighing under 1500 g, assumed increasing importance as a factor in perinatal mortality owing to a progressive worsening in the relative risk of perinatal mortality associated with low birth weight. Although regional differences in perinatal mortality persisted over this period, there occurred some lessening of the traditional inequality between western and eastern parts of the country. Finally, registered causes of perinatal mortality are reviewed. In the absence of other explanations the results of this analysis, collectively, suggest that much of the recent decline in perinatal mortality was perhaps due to changes in obstetric practice and in the clinical management of neonatal morbidity.     

Inequalities in mortality according to educational level in two large Southern European cities

BACKGROUND: In Spain, studies on social inequalities in mortality based on individuals are few due to the poor quality of information on occupation in death certificates. This study looks at the differences in mortality according to educational level, using individual information obtained through the linkage between the Death Register and the Municipal Census, in the cities of Madrid and Barcelona, Spain. METHODS: The study populations were residents of Madrid and Barcelona aged >24 years, who died in 1993 and 1994. Indicators obtained for each city and educational level were: age- and sex-specific mortality rates, and life expectancy at 25 years. Poisson regression models were fitted to obtain the relative risk (RR) of death for each educational level with respect to the reference level (higher education completed), adjusted for age. RESULTS: The mortality rate was lower among individuals with higher educational levels, while life expectancy at 25 years was higher. In both cities men and women with no education showed the highest mortality in all age groups, with very high RR in the youngest age group (RR for men aged 25-34 years = 7.08 in Madrid and 6.02 in Barcelona, whereas in women these RR were 6.33 and 5.63 respectively). In Barcelona the greater part of the overall mortality difference for the group aged 25-34 years was due to AIDS (acquired deficiency syndrome, 33.4% in men and 59.3% in women). CONCLUSION: The present study has found higher mortality (mainly from AIDS) among individuals with no academic qualifications thus drawing attention to the need to implement policies aimed at reducing these inequalities.     

Special education services and school performance in a regional cohort of low-birthweight infants at age nine

Previous research has shown that low birthweight is a predictor of several adverse educational outcomes, including special educational placement, by middle school age. Most low-birthweight follow-up studies that have extended to school age have focused on very small infants-- < 1500 or < 1000 g; less is known of the school age outcomes for infants with only moderately low birthweight (1500-2000 g). This study examines the prevalence of special educational placement and the relationship of such placement to grade retention, verbal and performance scores on tests of general intelligence, reading and maths achievement scores and classroom hyperactivity among low-birthweight children. In a regional birth cohort of 1105 infants born between 1984 and 1987 and weighing 500-2000 g, 868 children were available for follow-up at age nine. Information on special education placement as well as grade retention, intelligence, academic achievement and classroom behaviour was available on 645 (74% completion rate). Nearly a third of the cohort was classified as needing special education. Special education placement followed a birthweight gradient, occurring among 29.3% of children with birthweights 1500-2000 g, among 32.5% in children 1000-1500 g and 49.4% in children < 1000 g. Among children in special education, a similar birthweight gradient was found for maths achievement and hyperactivity, but not for reading achievement or IQ scores. Among children not in special education, only maths achievement showed such a decline with birthweight. A substantial proportion of low-birthweight children, including those of moderate low birthweight, receive special education services, although the need is greatest among those with the lowest birthweights. Maths achievement declined with birthweight regardless of educational placement. The medical and social risk factors that accompany low birthweight and may account for these findings, require further study.     

Temporal changes in the distribution of population risk factors attenuate the reduction in perinatal mortality

BACKGROUND AND OBJECTIVE: To examine and quantify the changing contribution of some risk factors to the perinatal mortality rate. METHODS: A population-based retrospective cohort study in Northern England compared stillbirth, neonatal, and perinatal mortality rates by birthweight, maternal age, plurality, and gender between 1982-1990 and 1991-2000. RESULTS: Atlhough the perinatal mortality rate fell by 20% between 1982-1990 and 1991-2000, the proportion of births in high risk groups (low and high birthweight, older mothers, and multiple births) increased. Standardizing the rates for 2000 to the risk factor distribution in 1982 resulted in lower rates. Changes in the birthweight distribution had the largest impact, particularly on neonatal mortality. Nearly a quarter of neonatal deaths in Northern England in 2000 can be attributed to the shift in the birthweight distribution since 1982, especially to the increase in low birthweight births. CONCLUSION: Changes in the distribution of birthweight, maternal age, and plurality over the study period attenuated the observed reduction in perinatal mortality. It is important to consider differences in the population prevalence of such risk factors to make valid geographic or temporal comparisons. Reasons for the secular shift in birthweight and the implications of any contributing change in obstetric practice require further investigation.     

A criterion for a standardized definition of low birthweight

A criterion for the definition of low birthweight (LBW) which is tailored to each population group is presented. The suggested criterion is based on an assumption according to which the distribution of birthweight is actually a mixture of the following two components: the predominant (including about 95% of the newborns and is normally distributed) and the residual (assumed to be mainly composed of newborns under extreme risk for perinatal mortality). The LBW category is defined to include a small but equal (for all groups) percentage of the predominant component. Thus, population groups which differ with respect to their specific predominant birthweight distribution are comparable with respect to the perinatal mortality risk. Application of the suggested definition is demonstrated using data from two ethnic groups in Israel. Results show a smaller percentage of female LBW than males in both population groups when using the suggested criterion. The reverse is observed (i.e. more male than female LBW), using the standard criterion (less than 2500 gm). The suggested criterion is shown to reduce the sex and ethnic differences in perinatal mortality among the respective LBW categories.     

Birthweight and perinatal mortality: paradoxes,social class,and sibling dependencies

BACKGROUND: Birthweight distributions among second-born infants depend on the birthweights of older siblings, with implications for weight-specific perinatal mortality. We wanted to study whether these relations were explained by socioeconomic levels, and to study time trends in a situation with decreasing perinatal mortality rates. METHODS: Births in the Norwegian Medical Birth Registry from 1967 to 1998 were linked to their mothers through their national identification numbers. The study population was 546 688 mothers with at least two singletons weighing >/==" BORDER="0">500 g at birth. Weight-specific perinatal mortality for second-born siblings in families with first-born siblings in either the highest or the lowest birthweight quartile was analysed. Maternal education and cohabitation status were used as measures of socioeconomic level. RESULTS: For all 500-g categories below 3500 g, mortality rates were significantly higher among second-born infants with an older sibling in the highest rather than the lowest weight quartile. This pattern was the same across three educational levels. The exclusion of preterm births did not change the effect pattern. A comparison of perinatal mortality among second siblings in terms of relative birthweight (z-scores) showed a reversal of the relative risks, although these were only significantly different from unity for the smallest infants. Conclusion The crossover in weight-specific perinatal mortality for second siblings by weight of first sibling is largely independent of socioeconomic level, and is not weakened by the decreasing perinatal mortality rates in the population over time. Family data should be taken into consideration when evaluating the risk of adverse pregnancy outcome relating to weight.     

The longitudinal study of the Northern Finland birth cohort of 1966

The Northern Finland birth cohort comprises 12,058 live births in 1966-96.3% of all births in the region. The investigation was started during pregnancy and the last follow-up of the total series was at the age of 14 years, when the coverage was still large. Smaller samples of the children and data for the study population from national registers were also examined for the older age groups. The health and development of the children was studied, with special emphasis placed on obtaining reliable incidence figures for neurological handicaps and their correlation with perinatal events. In particular, the correlation between low birthweight and handicapping conditions was documented thoroughly. The indicators predictive of low birthweight among the biological characteristics of the mother and the social conditions of the mother and family, included maternal smoking during pregnancy. The latter was associated not only with adverse perinatal outcome but also with reduction in educational achievement and height among survivors.     

Birthweight and behavioural problems in children: a modifiable effect?

BACKGROUND: Low birthweight has been shown to predict behavioural problems in children. Less is known about the effect of birthweight, and how this may interact with the social environment in determining behaviour in a general population sample. We have examined the relationship between birthweight and social factors on childhood psychological well-being. METHODS: Cross-sectional analysis of data on 5181 children aged 4-15 years from a randomly selected household population, the 1997 Health Survey for England. The main outcome measures were behavioural problems as defined by the Strengths and Difficulties Questionnaire (SDQ) in relation to birthweight and social environmental factors. RESULTS: Birthweight was a significant predictor of total difficulties score (odds ratio [OR] = 1.27, 95% CI : 1.07, 1.49), hyperactivity in boys (OR = 1.25, 95% CI : 1.05, 1.51), and peer problems in girls (OR = 1.24, 95% CI : 0.99, 1.53). There was a strong social class gradient in the prevalence of behavioural problems for all birthweight tertiles. Bivariate analysis showed that high total difficulties score was significantly more common in lower birthweight tertiles for social classes III non-manual and III manual (P:-value for trend 0.05 and 0.03, respectively). There were smaller, non-significant effects of birthweight on the prevalence of behavioural problems in social class I and II, and IV and V. Statistical tests for an interaction between birthweight and social class were not significant. CONCLUSIONS: Early life factors, such as birthweight and social class have important influences on psychological well-being in children. The birthweight effect is influenced by social factors, with the possibility that an advantaged social environment protects against the development of behavioural problems, and a disadvantaged environment increases the risk of behavioural problems, regardless of birthweight.     

Social inequalities in perinatal and infant mortality in the northern region of Belgium (the Flanders)

BACKGROUND: The study was intended to analyse the independent effect of some facets of the socio-economic status of both parents on perinatal, neonatal and post-neonatal mortality in the northern region of Belgium (the Flanders). METHOD: Perinatal data collected by the Study Centre for Perinatal Epidemiology were linked with socio-economic data collected by the district council. Mothers aged > or =25 years are included in the study. RESULTS: 50796 births were analysed. 452 infants died either before birth or during the first year of life. 52% of the foeto-infantile mortality occurred before birth and 57% of the infant mortality in the first week of life. The educational level was strongly related to foetal (p<0.001) and, to a lesser degree, to early-neonatal mortality (p=0.001). Employment did not correlate with any mortality item. Except for foetal mortality, the strongest correlation was always observed for maternal rather than paternal social items. In a logistic regression model, foetal mortality, perinatal mortality and infantile mortality remained strongly correlated with the educational level of the mother. Infant mortality beyond the first week of life was not correlated with any aspect of the social status of the parents. CONCLUSIONS: The educational level of the mother is the single most important determinant of infantile mortality in the Flanders representing the totality of hospital births by mothers aged > or =25 years in 1999 in the Flanders. KEY POINTS: Study Question: Does education, profession and actual employment of both parents, independently operates discrimination in the outcome of pregnancy up to one year? Results: Maternal education is the only significant and independent determinant of foetal as well as neonatal and foeto-infantile mortality. Results: The status of the mother is by far more important than that of the father in determining the outcome of pregnancy.     

Obstetric and neonatal care related to outcome. A comparison of two maternity hospitals.

Infants of birthweight up to 2500 g born in 1966 in two district hospitals were followed-up until their school medical examination at six years. Neonatal mortality rates differed in the two cohorts despite similar maternal age, parity, and social class distribution; differences in the management of labour and in neonatal care may have been responsible. Numbers were small but the prevalence of mild or more severe handicaps among the survivors did not differ significantly between the cohorts; an improved mortality was not achieved at the expense of an increased overall morbidity, although there was a suggestion of a difference in cerebral palsy prevalence. It is suggested that the neonatal mortality rate in conjunction with the prevalence of handicaps among the survivors of low birthweight infants be used as an indicator of the efficacy of perinatal care.