Ethnicity and infant health in Southern Brazil. A birth cohort study

Fernando C Barrosa, Cesar G Victorab and Bernardo L Hortac

a PAHO/WHO Latin American Centre for Perinatology and Human Development, Montevideo, Uruguay.
b Department of Social Medicine, Universidade Federal de Pelotas, RS, Brazil.
c Faculdade de Medicina, Universidade Católica de Pelotas, RS, Brazil.

Fernando C Barros, PAHO/WHO Centre for Perinatal Health, Hospital de clinicas, piso 16, Casilla de correo 627, Montevideo, Uruguay. E-mail: barrosfe{at}clap.ops-oms.org

Abstract

Background Black children present more health problems than white children, but little information is available from less developed countries. Ethnic inequalities may vary according to country, and studies from developing countries are needed to evaluate possible differentials and their magnitude, and identify social and health interventions.

Methods Birth cohort study in Pelotas, Southern Brazil. Information collected during the perinatal period in hospitals, and at home at 1, 3, 6 and 12 months of age. In all, 5305 children were studied at birth, 96.8% of the sample of 1461 at 6 months, and 93.4% of this sample at 12 months of age.

Results Of the children, 28% were African Brazilian. Socioeconomic position was lower among families of black children, and mothers presented a number of unfavourable characteristics. Black children presented higher prevalences of low birthweight (LBW), preterm and small-for-gestational age (SGA), were less often immunized, had more deficits of weight-for-age and height-for-age, and higher early neonatal and infant mortality. When a number of covariates, including antenatal care, were added to a multiple regression analysis the odds ratios were markedly reduced, but there was still a clear trend towards worse results for black children. Black mothers had some aspects of antenatal care of lower quality and were submitted less frequently to caesarean sections and episiotomies.

Conclusions Black infants experienced a much worse health status than white infants. Socioeconomic and other variables played a major role in determining inequalities between these ethnic groups. Antenatal care was especially important in explaining differentials in risk between black and white children.

Keywords Ethnicity, inequalities, infant health, infant mortality, neonatal mortality, breast feeding, nutrition, immunization, antenatal care, caesarean sections, episiotomy

Accepted 30 May 2001

Black children present more health problems than white children.1 Different reasons have been proposed to explain these inequalities,2 with socioeconomic differences and the sub-optimal use of health care3456 by black families being the most common. It is possible that ethnic inequalities in maternal and child health may vary in different countries and even within countries, but unfortunately most information on this subject originates from developed countries. Studies of ethnicity and child health from developing countries are needed to evaluate possible differentials and their magnitude, and identify social and health interventions.

Brazil has the second largest population of African origin,7 with 45% of blacks and mixed colour in 170 million inhabitants. Social and economic indicators are consistently worse for African Brazilians, with studies where self-reported ethnicity is reported showing that their income is 60–70% of that received by whites.7 A review of the scientific literature, however, could not identify any Brazilian publication on ethnicity and health of infants and children. In this paper we analyse the health status and a number of possible determinants of health among black and white children in a population-based birth cohort followed during the first year of life in Southern Brazil.

Population and Methods

Pelotas is a medium-sized city with a population of 350 000 located in the southernmost Brazilian State, Rio Grande do Sul. During 1993 a member of the research team paid daily visits to all five maternity hospitals in the city; there are virtually no home deliveries. All mothers were interviewed using a structured questionnaire which contained questions on demographic, socioeconomic, reproductive, behavioural, morbidity and health care utilization variables. The interviewers were resident doctors and medical students previously trained in interview techniques and anthropometry.

The follow-up study concentrated on the first year of life. Samples of the urban newborns were drawn and these children were visited at home at 1, 3, 6 and 12 months old. During the visits a new questionnaire was used and the children were weighed and measured. For the first and 3-months visit the team tried to locate a systematic sample of 655 children, based on the date and time of birth. The proportions located were 99.1% and 98.3%, respectively. These children were also visited at the ages of 6 and 12 months. With additional funds available for data collection, the sampling fraction was increased to 20% of all babies at these ages, including the 12% visited at one and 3 months, plus an 8% systematic sample of the remaining children. Additionally, all children with low birthweight (LBW, <2500 g) were included in the final two visits. The final sample was weighted in the analysis to reproduce the proportion of LBW in the original cohort. The proportions traced at 6 and 12 months were 96.8% and 93.4%, respectively. Table 1Go shows the sample size for the maternity hospital phase and the four home visits of this longitudinal study, and the numbers and proportions actually found.


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Table 1 Sample size for the perinatal study and each of the four home visits, and number and proportion of infants actually found. Pelotas birth cohort, 1993–1994
 
The follow-up started in February 1993, when the first child completed one month of life, and was completed in December 1994, when the last child completed one year of life. The follow-up visits were carried out by professionals and students of medicine, nutrition and nursing, trained in interview techniques and anthropometry. The supervisors repeated a random sample of 5% of the interviews and confirmed the high quality of the collected information.

The study was conceptually based on a hierarchical model8 summarized in Table 2Go. The variable in the first and more distal level is ethnicity, and in the second level socioeconomic variables are included. This means that being black or white is one determinant of the socioeconomic situation. In the third level are three groups of variables of similar hierarchical importance: biological, demographic and cultural. In the fourth level are health care utilization outcomes. In this level, the variable antenatal care was also treated as a mediating factor for the fetal and infant outcomes listed in the fifth hierarchical level. For example, the utilization of antenatal care is an outcome of health care utilization but may also influence the prevalence of LBW or infant mortality.


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Table 2 Hierarchical model used for the study of infant health and ethnicity

 
Information regarding the ethnicity of the mother and father was collected from the mother (who was asked what her colour was and also the colour of the child's father). Parents of black and mixed colour were classified together as blacks.

The socioeconomic variables of the second level were family income and maternal education. Family income was calculated by asking the mother the amount of money received by all those in the family who were working in the month before the interview. This variable was then transformed into monthly minimum wages (one minimum wage should theoretically, be sufficient to maintain a family of four members, and at the time of the research was equivalent to US$80.00). Maternal education was calculated as the number of years of schooling completed successfully.

In the third hierarchical level were demographic, biological and cultural variables. For marital status mothers were asked whether they lived with the child's father or another partner or alone. Maternal age was measured in completed years at childbirth and parity as the number of previous deliveries. Mothers were measured by the interviewers and the pre-pregnancy weight was obtained from mothers' recall or copied from the mothers' antenatal card, if the first consultation occurred before 14 weeks of gestation.

Among the cultural variables, mothers were considered as smokers if they smoked any number of cigarettes during pregnancy. Information on maternal work during pregnancy was obtained from three questions on work at home and outside home. A score was created giving one point to positive answers and zero to negative answers for the following questions: whether they considered work at home as light, heavy or very heavy, if they worked outside the home in a standing position, and if they worked outside the home lifting weight. Mothers with a zero score were considered as light workers during pregnancy, those with one point as moderate, and those with two or three points as heavy workers. For information on planned pregnancy mothers were asked directly whether they planned their pregnancy or not. For the evaluation of social support during pregnancy, mothers were asked three questions on how they felt about the support given by their partner/husbands, families and friends. It was considered that they had social support if they considered that at least one of the three groups provided good support during pregnancy.

The fourth hierarchical level comprised health care utilization outcomes of mothers and infants. Mothers were asked if they had visited a medical doctor during pregnancy with the objective of pregnancy control and, if positive, how many times they visited an antenatal clinic. Those having one or more visits were considered as having attended for antenatal care. The variable antenatal care was entered into the multiple regression model as a covariate influencing different outcomes, with the following categories: no attendance, 1–4, 5–9, >=10 attendances. Mothers were asked whether the doctor had performed a list of activities during antenatal care. These were: asked the date of the last menstrual period, weighed the mother, measured uterine fundal height, measured blood pressure, performed gynaecological examination, examined breasts, encouraged breastfeeding, prescribed iron, vitamins and tetanus toxoid.

Mothers were also asked if their baby was delivered vaginally or by a caesarean section, and for those with vaginal births it was inquired whether they were cut during labour or delivery by the health care person, either doctor or nurse, to facilitate the birth (episiotomy). The children's immunization coverage was evaluated during the home visit at 12 months of age. Mothers were asked about the number of doses of each vaccine and the child's immunization card was checked. During the same 12-months home visit mothers were also asked if their children has been hospitalized during the first year of life.

The fifth hierarchical level was represented by fetal and infant health outcomes. Birthweight was measured by the maternity hospital staff with paediatric scales with a precision of 10 g checked weekly for their accuracy. Length was measured by the research interviewers with the babies in the supine position with an AHRTAG (London, UK) infantometer. Gestational age was calculated based on the last menstrual period (LMP). Fourteen per cent of the mothers did not provide information on their LMP and were considered as missing information for the calculation of preterm births and small-for-gestational age babies (SGA). The following definitions were adopted: LBW <2500 g, preterm <37 weeks of gestation), SGA according to WHO,9 as birthweight for gestational age and sex below the 10th percentile of the curves of Williams et al.10 Two paediatricians repeated 5% of the interviews and gestational age evaluations to check the quality and accuracy of the information. They found that all interviews had actually been done and the quality of the information was good.

Information on breastfeeding status was collected from the mother at the 3 months of age interview and the mean duration of full breastfeeding at 12 months.

The infants were weighed and measured at 6 and 12 months of age. Weight was obtained using a Salter type weighing scale model CMS, with capacity of 25 kg and 100 g precision. Length was measured with the children in supine position with an AHRTAG portable infantometer, with 1 mm precision. The cut-offs for weight and length were –1.28 z-scores, calculated based on the median of the NCHS reference.11

The mortality component of the study included all fetal, neonatal and post-neonatal deaths. All hospitals, cemeteries, Civil Registration Offices, and the regional office of the state Secretariat of Health were visited regularly during 1993 and 1994 in order to detect deaths of children of the 1993 birth cohort. A total of 166 deaths (including 55 fetal deaths) were detected in the period: 21 at home, 4 in the nursery, 3 in the hospital ward, and the remainder in intensive care units. It was possible to interview the assistant doctors and family members of all deceased infants, with the exception of one case of home death in which the address was missing.

The study of hospital morbidity monitored all hospital admissions of the cohort children. From January 1993 until December 1994 all city hospitals were visited regularly. The cause of the hospitalization was ascertained by two paediatricians, working independently, based on the hospital case-notes, interview with the mother, and—if necessary—an interview with the paediatricians in charge of the case. If agreement about the cause of hospitalization was not reached, a meeting with a third referee would take place and the three would reach a consensus regarding the diagnosis.

For multivariate analysis, the effects of mediating variables in the relation between children's ethnicity and the outcomes of interest were examined, aiming at identifying the variables responsible for the differences between white and black children.

Results

In all, 5305 births (5249 livebirths) were studied in the perinatal component of the study, 1414 infants at 6 months of age and 1363 at 12 months of age. Seventy-two per cent of the city children had both parents white, 17% had both parents black, and 11% had one parent black and the other white. Since the socioeconomic characteristics, measured by maternal education and family income, were the same for children with one or two black parents, and there was no ‘dose-response’ effect for 11 of the 15 outcomes in the analyses of the three ethnic groups, we decided to analyse together the children with either one or two black parents, and compare their characteristics and outcomes with those of children with two white parents. This means that the African Brazilian children could have both parents black, white mothers and black fathers or black mothers and white fathers. For the outcomes antenatal care, caesarean sections and episiotomies, however, African Brazilian mothers were compared with white mothers.

Table 3Go shows that families of black children were poorer and the mothers were less educated. Mothers of black children were also more frequently adolescents, single, multiparous, had fewer planned pregnancies, received less family support during pregnancy, smoked more often and more frequently engaged in moderate or heavy work during pregnancy. Weight before pregnancy, height, and body mass index, however, were similar for the two groups of mothers.


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Table 3 Demographic, social, and biological characteristics of mothers according to ethnicity of the child. Pelotas, Brazil, 1993
 
Black mothers attended less often for antenatal care and had fewer episiotomies and caesarean sections (Table 4Go). Black children presented higher prevalences of unfavourable health indicators at birth (LBW, preterm, SGA) than whites, and their mothers were less likely to attend for antenatal care Additionally, black children were less often immunized, presented more deficits of weight-for-age and height-for-age at 6 and 12 months old, were hospitalized more often in the first year of life, and had higher early neonatal and infant mortality. On the other hand, breastfeeding rates of black children at 3 months of age were slightly higher, and their mean duration of full breastfeeding was 5.6 months in comparison to 4.9 months for white children (not in the Table).


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Table 4 Health indicators and health care utilization variables according to ethnicity of children. Pelotas, Brazil, 1993–1994
 
Table 5Go shows the results of logistic regression analyses. The Table includes the unadjusted odds ratios (OR) and two sets of adjusted ratios: in the third column, those adjusted for socioeconomic variables (family income and maternal education), and in the last column those also adjusted for marital status, maternal age, parity, planned pregnancy, social support, smoking during pregnancy, work during pregnancy and antenatal care (for all variables except the outcome antenatal care). The unadjusted analyses showed clear disadvantages for black children, indicated by the positive crude OR, for all outcomes, with the exception of caesarean sections, episiotomies and breastfeeding at 3 months of age. There were substantial decreases in the OR after adjusting for socioeconomic covariates (Model 1), but important differences between the two ethnic groups still remained for practically all outcomes, indicating disadvantages for the black children. Caesarean sections, episiotomies and lack of breastfeeding at 3 months of age were still less frequent in blacks. When other covariates were added to the socioeconomic variables (Model 2), the differences in OR between black and white children reduced further and the CI included unity, with the exception of the anthropometric outcomes measured at 6 months old. On the other hand, black children were still more likely to be breastfed at 3 months of age (OR = 0.67; 95% CI : 0.51–0.87). Regarding maternal health care, the smaller risk of caesarean section among black women disappeared after the inclusion in the model of the full range of covariates, but they were still 30% less likely to undergo an episiotomy.


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Table 5 Logistic regression analysis of health indicators and heath care utilization variables (value of unity ascribed to white children). Pelotas, Brazil, 1993–1994
 
An important part of the reduction in the OR occurred after the inclusion of antenatal care in the model. For LBW, the OR after the inclusion of all variables of Model 2 with the exception of antenatal care was 1.25 (95% CI : 1.01–1.53), and after the inclusion of antenatal care the OR was further reduced to 1.14 (95% CI : 0.93–1.41). The reductions in the OR of other outcomes after the inclusion of antenatal care were: for preterm birth—from 1.36 (95% CI : 1.06–1.76) to 1.24 (95% CI : 0.96– 1.61); for infant mortality—from 1.50 (95% CI : 1.00–2.25) to 1.37 (95% CI : 0.91–2.07); for weight-for-age at 12 months of age—from 1.43 (95% CI : 1.03–1.97) to 1.36 (95% CI : 0.98– 1.89); for length-for-age at 12 months of age—from 1.37 (95% CI : 1.01–1.85) to 1.32 (95% CI : 0.97–1.80); and for complete immunization at 12 months of age—from 1.39 (95% CI : 1.01– 1.91) to 1.30 (95% CI : 0.94–1.75).

In relation to the checklist of activities performed by the doctor during antenatal care, the activities with different prevalences for white and black mothers were: gynaecological examination —not performed in 21.0% (95% CI : 19.7–22.3%) of the white mothers and 25.8% (95% CI : 23.2–28.4%) of the black mothers; breast examination—not performed in 48.3% (95% CI : 46.7–49.9%) of the whites and 57.8% (95% CI : 54.9– 60.7%) of blacks; vitamins—not prescribed for 78.2% (95% CI : 76.9–79.5%) of the whites and 83.4% (95% CI : 81.2–85.6%) of the blacks; tetanus toxoid for non-previously immunized mothers—not prescribed for 39.3% (95% CI : 37.6–41.0%) of the white mothers and 31.6% (95% CI : 28.6–34.6%) of the black mothers.

Discussion

This study has the advantage of being longitudinal; the collection of information started at birth and the babies were followed-up with four home visits up to 12 months of age. Ethnicity is difficult to measure in epidemiological studies,12 and we used a self-report criterion for the classification of ethnicity of the children's mothers. As the fathers could not be interviewed, we relied on the information provided by the mothers for their ethnic classification. The possibility that this system could lead to some degree of misclassification cannot be ruled out.

Children with one or two black parents were considered together in this study, and compared with children with two white parents. This was done because when three groups were analysed—both parents white, one parent black and one white, and both parents black—a ‘dose-response’ effect was found only for 4 out of the 15 outcomes studied. It is possible that the absence of a dose-response effect for other variables was due to the lack of socioeconomic differences between families with one or both black parents. In another study in Brazil the authors found income differences between individuals who were ethnically mixed and those classified as black.7

Families of black children presented important socioeconomic and demographic disadvantages in comparison with those of white children. Mothers were less educated, family income was half that of the families of white children, and the proportions of single mothers, adolescents, and multiparae were also much higher. The prevalences of unplanned pregnancies, lack of social support, and engagement in heavy work during pregnancy were much higher for mothers of black children. All these inequalities contributed importantly to the worse health outcomes of black infants.

Health care during pregnancy and delivery varied substantially for black and white mothers. Black mothers more often did not attend for antenatal care, and the attenders more frequently started later (44% after the third month of pregnancy in comparison with 27% of the whites) and had fewer consultations (mean of 6.7 attendances compared with 8.3 for the whites). In addition, the analysis of a checklist of activities that should be performed by the doctor during care shows that doctors prescribed less vitamins and performed fewer physical examinations, both gynaecological and of breasts, for mothers of black children. On the other hand, doctors prescribed more tetanus toxoid for black than for white non-immunized pregnant women. Although this was information provided by the mothers and not validated, so we cannot be sure that it reflects the truth, it suggests that the quality of care provided for white and black mothers is not the same, appearing to be worse for black mothers. The only positive aspect of antenatal care for black mothers is that doctors prescribed tetanus toxoid more often, but this could be because they considered that black babies were at increased risk of neonatal tetanus. A lower quality of antenatal attention for black women has also been described in the US, where black women received less advice on smoking and alcohol than whites.13

During delivery black mothers less frequently had episiotomies and caesarean sections. One reason why mothers of black children had less caesarean sections could be their more frequent low socioeconomic status, as in this population the prevalence of caesarean sections is directly associated with family income.14 Although caesarean section rates remained lower for black women after controlling for socioeconomic variables, it is possible that other residual covariates could be responsible for this difference.15 With the inclusion of the full range of covariates in the model the differences in caesarean sections between whites and blacks ceased to exist. Unlike the results of the present study, black mothers in California had a lower risk of caesarean section in unadjusted analysis, but were 24% more likely to undergo a caesarean section than whites after adjustment for other variables.16 In relation to episiotomies, other studies have also found ethnic variations in this practice: in the UK13 episiotomies were performed twice as commonly in women from the Indian subcontinent as in whites, while in The Netherlands, episiotomies were less frequent in Blacks, Asians and Mediterraneans (Turks and Moroccans) than in Dutch women.17 There are suggestions that black women are more likely to deliver with their perineums intact,18 but this does not seem to be the reason why black women had lower rates of episiotomies in Pelotas. In fact, as episiotomies were performed in 95% of the white primiparae, regardless of the socioeconomic situation, it seems that performing episiotomies in this area can be considered the good standard of medical care and therefore the lower rates observed among black women could be due to less medical attention. In another study conducted in 105 hospitals in 14 Latin American countries, the median rate of episiotomy for primiparae was 92.3%, showing that the universal practice of episiotomies is widespread in the region (Althabe F, personal communication).

The health disadvantages of black children were very clear at birth, with higher proportions of LBW, preterm and SGA. Regarding the two latter outcomes, since the proportion of black children for whom the information on gestational age was lacking was much higher than for white children (20% and 11.9%, respectively); and mothers missing this information had more LBW babies, it appears that the differences between black and white children could be even higher for these indicators had all the population been included.

During the first year black infants had worse nutritional status and an increased risk of death, even though they were breastfed for slightly longer periods than whites. It seems that the small increase in breastfeeding was not sufficient to counterbalance the negative effects of all the disadvantages the black children had. The better breastfeeding performance of black mothers is in contrast with the findings of a study conducted 10 years before in the same area, when breastfeeding was found to be more common among children of better-off families.19 However, in two Brazilian metropolitan areas (São Paulo and Recife) higher prevalences of breastfeeding were described for black children as opposed to white and ethnically mixed children.20

The reduction in all crude OR for black children prompted by the inclusion of socioeconomic variables in the model indicates that a good portion of the inequalities in health indicators between black and white children can be explained by these variables.2122 In addition, when the other covariates were added to the analysis the OR were further markedly reduced, but there was still a clear trend towards worse results for black children. The fact that for most outcomes the OR now included unity is probably because the CI were large, due to the small sample size. Nevertheless, with the exception of breastfeeding, episiotomy and caesarean section, the risks of black children were still between 14% and 53% higher, and this could be accounted for by residual confounding.15 For example, our measures of socioeconomic position could have a certain degree of error. Also, other variables, not included in the analytical model of this study, may have accounted for the observed differences. These variables could be of various types, e.g. social, economic, psychological, or related to the quality of care. This study cannot rule out the possibility that black families suffer some kind of discrimination when trying to use health services (e.g. having more difficulty in obtaining assistance in antenatal care or child health clinics) since the vast majority of medical doctors are white.

The reduction and elimination of the wide gap that exists in the health status of black and white children in southern Brazil will require structural social and political changes with actual improvements in a number of areas, especially education and access to jobs and comparable salaries for African Brazilians. This study has shown that there are marked differences in the utilization of health care by ethnic groups, a finding also described in other areas of care in the US.23 In addition, it appears that the quality of care offered to pregnant women varies according to their ethnicity, and black women may receive a lower quality of care. The health sector will have to conduct an in-depth evaluation of these aspects in order to provide the population with a better quality of medical care, with no ethnic inequalities.


KEY MESSAGES

  • Mothers of black children in Southern Brazil were less educated, more often single, adolescents, and multiparous, had more unplanned pregnancies, lacked social support during pregnancy and engaged in heavy work.
  • Black mothers attended less for antenatal care; the attenders more often started later and had fewer consultations. During consultations doctors prescribed less vitamins and performed less gynaecological and breast examinations for black mothers, but they prescribed more tetanus toxoid.
  • During delivery black mothers were less frequently subjected to episiotomies and caesarean sections.
  • Black children presented higher prevalences of low birthweight, preterm and small-for-gestational age, and during the first year had worse nutritional status and an increased risk of death.
  • The risks of worse outcomes of black children were reduced by adjustment for socioeconomic variables and a number of other covariates, but even after all adjustments there was still a clear trend towards worse outcomes for black children.

 

Acknowledgments

This study has been financed by the Brazilian Council of Research (CNPq) and the European Union.

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