INCREASING PRE-TERM AND LOW-BIRTH- WEIGHT RATES OVER TIME AND THEIR IMPACT ON INFANT MORTALITY IN SOUTH-EAST BRAZIL

Factors associated with neonatal-near miss: birth cohorts in three Brazilian cities - Ribeirão Preto, Pelotas and São Luís, Brazil

The aim of this study was to investigate the association of sociodemographic factors, lifestyle, maternal reproductive profile and prenatal and childbirth care with neonatal near miss (NNM) morbidity in four birth cohorts. This study involved four population-based birth cohorts: Ribeirão Preto (RP) and São Luís (SL) (2010), Pelotas 2004 (PEL04) and 2015 (PEL15). NNM was defined when one or more of the following conditions were present: birthweight <1,500 g, 5-minute Apgar score <7, gestational age <32 weeks, and report of congenital malformations. The covariates were obtained with questionnaires applied to the puerperal women. Some particularities between cohorts were identified. In the RP and SL cohorts, factors of the more distal levels (sociodemographic, lifestyle, and reproductive profile) were associated with NNM. On the other hand, proximal factors related to healthcare were more significant for the occurrence of NNM in PEL. Only the absence of prenatal care was associated with NNM in all cohorts: RP (OR=4.27, 95%CI 2.16-8.45), SL (OR=2.32, 95%CI 1.09-4.94), PEL04 (OR=4.79, 95%CI 1.59-14.46), and PEL15 (OR=5.10, 95%CI 2.60-9.97).

Prematurity and body composition at 6, 18, and 30 years of age: Pelotas (Brazil) 2004, 1993, and 1982 birth cohorts

Background

We aimed to investigate the association between preterm birth and body composition at 6, 18, and 30 years of age using data from three population-based birth cohort studies.

Methods

Gestational age (GA), defined by the date of the last menstrual period (categorized in ≤33, 34–36, and ≥ 37 weeks), was gathered in the first 24-h after delivery for all live births occurring in the city of Pelotas, Brazil, in 2004, 1993 and 1982. Body composition was assessed by air-displacement plethysmography. Outcomes included fat mass (FM, kg), percent FM (%FM), FM index (FMI, kg/m²), fat-free mass (FFM, kg); percent FFM (%FFM), FFM index (FFMI, kg/m²), body mass index (BMI, kg/m² at 18 years in the 1993 cohort and 30 years in the 1982 cohort), and BMI Z-score (at 6 years in the 2004 cohort). We further explored the association of birth weight for GA with body composition indicators and BMI. Crude and adjusted linear regressions provided beta coefficients with 95% confidence intervals (95%CI).

Results

A total of 3036, 3027, and 3369 participants, respectively, from the 2004, 1993, and 1982 cohorts were analyzed. At 6 years, preterm boys (born at 34–36 weeks) presented lower adjusted mean of FM (β = − 0.80 kg, − 1.45;-0.16, p = 0.046), %FM (β = − 2.39%, − 3.90;-0.88, p = 0.008), FMI (β = − 0.70 kg/m², − 1.13;-0.27, p = 0.004) as well as lower FFM (β = − 0.4 kg, − 0.77; − 0.12, p = 0.010) and FFMI (β = − 0.3 kg/m², − 0.46;-0.10, p < 0.001), and BMI Z-score (β = − 0.69,; − 0.99;-0.40, p < 0.001); but higher %FFM (β = 2.4%, 0.87;-3.90, p = 0.008), when compared to boys born at term (≥37). At 30 years, FM (15.7 kg, 0.25;31.1, p = 0.102) was higher among males born at ≤33 weeks. No association was observed for females from the three cohorts and for 18-year-old males. The association of birth weight for GA with body composition and BMI was not significant in any cohort. At 6 years, SGA boys had lower FFMI than boys AGA.

Conclusions

Our results suggest that preterm birth is associated with decreased body fat and fat-free mass in childhood but higher fat mass in adulthood. Nevertheless, results were only significant for males. SGA boys also showed lower FFMI.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-021-10368-w.

Changes in Infant and Neonatal Mortality and Associated Factors in Eight Cohorts from Three Brazilian Cities

Stillbirth (SBR), perinatal (PMR), neonatal (NMR) and infant mortality rates (IMR) are declining in Brazil and the factors associated with these falls are still being investigated. The objective of the present study was to assess changes in SBR, PMR, NMR and IMR over time and to determine the factors associated with changes in NMR and IMR in eight Brazilian cohorts. All cohorts are population-based (Ribeirão Preto in 1978/79, 1994 and 2010; Pelotas in 1982, 1993 and 2004; and São Luís in 1997/98 and 2010). Were included data on 41440 children. All indicators were decreased, except in the city of Pelotas, from 1993 to 2004, and except SBR in São Luís. Sociodemographic variables seem to be able to explain reductions of NMR and IMR in Ribeirão Preto, from 1978/79 to 1994, and in São Luís. In Ribeirão Preto, from 1994 to 2010 declines in NMR and IMR seem to be explained by reductions in intrauterine growth restriction (IUGR). Newborn’s gestational age had diminished in all cohorts, preventing even greater reductions of NMR and IMR. Improved sociodemographic variables and reduction of IUGR, seem to be able to explain part of the decrease observed. NMR and IMR could have been reduced even more, were it not for the worsening in gestational age distribution.

[Telephone monitoring service for pregnant women and impact on prevalence of prematurity and associated risk factors in Piracicaba, São Paulo State, Brazil]

This study aims to assess the impact of a telephone monitoring service on prevalence of prematurity and to analyze associated risk factors using data on 2,739 pregnant women. Estimation was based on hierarchical multiple logistic regression, with p ≤ 0.05 for variables to remain in the model. Prevalence of preterm birth was 8.34% in monitored pregnant women and 10.18% in unmonitored women (p = 0.0058). Prevalence of preterm birth was inversely proportional to the number of monitoring calls (p < 0.0001). Variables associated with prematurity were maternal age < 19 years, history of death of two or more children, multiple pregnancy, diabetes, hypertension, fewer monitoring calls, extended standing or lifting heavy weights at work, smoking, fewer prenatal visits, no ultrasound examination, gestational diabetes, multiple pregnancy, and fetal abnormality. This low-cost strategy proved effective for reducing the preterm birth rate.

Changes in perinatal health in two birth cohorts (1997/1998 and 2010) in São Luís, Maranhão State, Brazil

The objective of this study was to analyze changes in perinatal health in two birth cohorts started in 1997/1998 and 2010, respectively, in São Luís, Maranhão State, Brazil. A total of 2,493 live born infants were included in 1997/1998 and 5,166 in 2010. Low birth weight (LBW) rate did not change (8.5% in 1997/1998 and 8.6% in 2010). Preterm birth (PTB) rate also remained stable (13.2% in 1997/1998 and 13% in 2010). Teenage deliveries and births to single mothers decreased. Maternal schooling and prenatal care coverage increased. Intrauterine growth restriction (IUGR) decreased from 13.3% to 10.6% (p < 0.001). The perinatal mortality rate decreased from 36.6 to 20.7 per 1,000 (p < 0.001) and the infant mortality rate (IMR) dropped from 28.5 to 12.8 per 1,000 (p < 0.001). The cesarean rate increased from 34.1% to 47.5% (p < 0.001). In conclusion, despite favorable changes in socio-demographic, behavioral, and health service factors and decreasing rates of IUGR and perinatal and infant mortality, LBW and PTB remained stable, while the cesarean rate increased.

Use of a monitoring tool for growth and development in Brazilian children – systematic review

Objective:

To assess the use of a health monitoring tool in Brazilian children, with emphasis on the variables related to growth and development, which are crucial aspects of child health care.

Data source:

A systematic review of the literature was carried out in studies performed in Brazil, using the Cochrane Brazil, Lilacs, SciELO and Medline databases. The descriptors and keywords used were “growth and development”, “child development”, “child health record”, “child health handbook”, “health record and child” and “child handbook”, as well as the equivalent terms in Portuguese. Studies were screened by title and summary and those considered eligible were read in full.

Data synthesis:

Sixty-eight articles were identified and eight articles were included in the review, as they carried out a quantitative analysis of the filling out of information. Five studies assessed the completion of the Child's Health Record and three of the Child's Health Handbook. All articles concluded that the information was not properly recorded. Growth monitoring charts were rarely filled out, reaching 96.3% in the case of weight for age. The use of the BMI chart was not reported, despite the growing rates of childhood obesity. Only two studies reported the completion of development milestones and, in these, the milestones were recorded in approximately 20% of the verified tools.

Conclusions:

The results of the assessed articles disclosed underutilization of the tool and reflect low awareness by health professionals regarding the recording of information in the child's health monitoring document.

[Prevalence of preterm birth according to birth weight group: a systematic review]

OBJECTIVE

To estimate the prevalence of preterm birth by categories of birth weight, and to obtain an equation to correct the estimates.

METHODS

Systematic review of the Brazilian literature published from 1990 to 2012, to identify studies with primary collection of data on birth weight and gestational age. Twelve studies were selected and contributed for tabulations of preterm prevalence according to 100 g birth weight categories. These results were combined using sex-specific fractional polynomial equations and the resulting curves were compared with results from the Live Birth Information System for the years 2000, 2005, 2010 and 2011.

RESULTS

For all birth weight categories, preterm prevalence estimates based on primary studies had a higher prevalence than those of the the Live Birth Information System. The prevalence reported by the Live Birth Information System was of 7.2% in 2010, about 38.0% lower than the estimated prevalence of 11.7% obtained with the correctional equation.

CONCLUSIONS

Information reported by the Live Birth Information System on preterm prevalence does not reflect the true magnitude of the problem in Brazil, and should not be used without the correction factors proposed in the present analyses.

Variables associated with cognitive, behavioral and emotional development: a cohort of schoolchildren

This study aimed to identify possible variables associated with cognitive, behavioral and emotional development in a cohort of school children, based on biological (sex, gestational age and birth weight) and socioeconomic variables (marital status, maternal and paternal education, occupation of head of household, socioeconomic status, and number of household members). We evaluated 790 children born in a cohort of Ribeirão Preto (SP), Brazil, with 10/11 years of age. The Raven Test was used for cognitive assessment and the Strengths and Difficulties Questionnaire was utilized for emotional and behavioral assessment. By means of multivariate logistic regression analysis (CI 95%) we found that: 1) low maternal schooling was associated with behavioral and emotional problems and poor cognitive function, 2) being female was considered as a protective factor against behavioral problems and 3) low birth weight and prematurity were not associated with the outcomes investigated.

Infant mortality in a very low birth weight cohort from a public hospital in Rio de Janeiro, RJ, Brazil

OBJECTIVES: to evaluate infant mortality in very low birth weight newborns from a public hospital in Rio de Janeiro, Brazil (2002-2006). METHODS: a retrospective cohort study was performed using the probabilistic linkage method to identify infant mortality. Mortality proportions were calculated according to birth weight intervals and period of death. The Kaplan-Meier method was used to estimate overall cumulative survival probability. The association between maternal schooling and survival of very low birth weight infants was evaluated by means of Cox proportional hazard models adjusted for: prenatal care, birth weight, and gestational age. RESULTS: the study included 782 very low birth weight newborns. Of these, (28.6%) died before one year of age. Neonatal mortality was 19.5%, and earlyneonatal mortality was 14.9%. Mortality was highest in the lowest weight group (71.6%). Newborns whose mothers had less than four years of schooling had 2.5 times higher risk of death than those whose mothers had eight years of schooling or more, even after adjusting for intermediate factors. CONCLUSIONS: the results showed higher mortality among very low birth weight infants. Low schooling was an independent predictor of infant death in this low-income population sample.

Birth weight, current body mass index, and insulin sensitivity and secretion in young adults in two Latin American populations

BACKGROUND AND AIMS

Although studies have shown association of birth weight (BW) and adult body mass index (BMI) with insulin sensitivity in adults, there is limited evidence that BW is associated with insulin secretion. We assessed the associations between BW and current BMI with insulin sensitivity and secretion in young Latin American adults.

METHODS AND RESULTS

Two birth cohorts, one from Ribeirao Preto, Brazil, based on 1984 participants aged 23-25 years, and another from Limache, Chile, based on 965 participants aged 22-28 years were studied. Weight and height at birth, and current fasting plasma glucose and insulin levels were measured. Insulin sensitivity (HOMA%S) and secretion (HOMA%β) were estimated using the Homeostatic Model Assessment (HOMA2). Multiple linear regression analyses were carried out to test the associations between BW and adult BMI z-scores on log HOMA%S and log HOMA%β. BW z-score was associated with HOMA%S in the two populations and HOMA%β in Ribeirao Preto when adult BMI z-score was included in the model. BW z-score was associated with decreasing insulin secretion even without adjusting for adult BMI, but only in Ribeirao Preto. BMI z-score was associated with low HOMA%S and high HOMA%β. No interactions between BW and BMI z-scores on insulin sensitivity were shown.

CONCLUSIONS

This study supports the finding that BW may affect insulin sensitivity and secretion in young adults. The effect size of BW on insulin status is small in comparison to current BMI.

Maternal and child health in Brazil: progress and challenges

In the past three decades, Brazil has undergone rapid changes in major social determinants of health and in the organisation of health services. In this report, we examine how these changes have affected indicators of maternal health, child health, and child nutrition. We use data from vital statistics, population censuses, demographic and health surveys, and published reports. In the past three decades, infant mortality rates have reduced substantially, decreasing by 5·5% a year in the 1980s and 1990s, and by 4·4% a year since 2000 to reach 20 deaths per 1000 livebirths in 2008. Neonatal deaths account for 68% of infant deaths. Stunting prevalence among children younger than 5 years decreased from 37% in 1974-75 to 7% in 2006-07. Regional differences in stunting and child mortality also decreased. Access to most maternal-health and child-health interventions increased sharply to almost universal coverage, and regional and socioeconomic inequalities in access to such interventions were notably reduced. The median duration of breastfeeding increased from 2·5 months in the 1970s to 14 months by 2006-07. Official statistics show stable maternal mortality ratios during the past 10 years, but modelled data indicate a yearly decrease of 4%, a trend which might not have been noticeable in official reports because of improvements in death registration and the increased number of investigations into deaths of women of reproductive age. The reasons behind Brazil's progress include: socioeconomic and demographic changes (economic growth, reduction in income disparities between the poorest and wealthiest populations, urbanisation, improved education of women, and decreased fertility rates), interventions outside the health sector (a conditional cash transfer programme and improvements in water and sanitation), vertical health programmes in the 1980s (promotion of breastfeeding, oral rehydration, and immunisations), creation of a tax-funded national health service in 1988 (coverage of which expanded to reach the poorest areas of the country through the Family Health Program in the mid-1990s); and implementation of many national and state-wide programmes to improve child health and child nutrition and, to a lesser extent, to promote women's health. Nevertheless, substantial challenges remain, including overmedicalisation of childbirth (nearly 50% of babies are delivered by caesarean section), maternal deaths caused by illegal abortions, and a high frequency of preterm deliveries.

[Avoidable causes of infant mortality in Brazil, 1997-2006: contributions to performance evaluation of the Unified National Health System]

Infant deaths were classified as avoidable, non-avoidable, and resulting from ill-defined conditions, from 1997 to 2006, using the Brazilian List of Avoidable Causes of Mortality. Non-linear regression was used to calculate trends in cause-specific infant mortality rates. There was a significant decline in both avoidable deaths and deaths from ill-defined causes (p < 0.001). Avoidable deaths decreased by 37% overall. Mortality avoidable through adequate intrapartum care and adequate neonatal care decreased by 27.7% and 42.5%, respectively, while mortality avoidable through adequate prenatal care increased by 28.3%. In conclusion, health services contributed to the reduction in infant mortality. The decrease in ill-defined causes of death indicates expanded access to health services. The increase in access to intrapartum and neonatal care contributed to the reduction in infant deaths. The increase in mortality avoidable through adequate prenatal care indicates the need for improvement in prenatal care.

The epidemiologic paradox of low birth weight in Brazil

OBJECTIVE

To examine whether the low birth weight (LBW) paradox exists in Brazil.

METHODS

LBW and cesarean section rates between 1995 and 2007 were estimated based on data from SINASC (Brazilian Live Births Database). Infant mortality rates (IMRs) were obtained using an indirect method that correct for underreporting. Schooling information was obtained from census data. Trends in LBW rate were assessed using joinpoint regression models. The correlations between LBW rate and other indicators were graphically assessed by lowess regression and tested using Spearman's rank correlation.

RESULTS

In Brazil, LBW rate trends were non-linear and non-significant: the rate dropped from 7.9% in 1995 to 7.7% in 2000, then increased to 8.2% in 2003 and remained nearly steady thereafter at 8.2% in 2007. However, trends varied among Brazilian regions: there were significant increases in the North from 1999 to 2003 (2.7% per year), and in the South (1.0% per year) and Central-West regions (0.6% per year) from 1995 to 2007. For the entire period studied, higher LBW and lower IMRs were seen in more developed compared to less developed regions. In Brazilian States, in 2005, the higher the IMR rate, the lower the LBW rate (p=0.009); the lower the low schooling rate, the lower the LBW rate (p=0.007); the higher the number of neonatal intensive care beds per 1,000 live births, the higher the LBW rate (p=0.036).

CONCLUSIONS

The low birth weight paradox was seen in Brazil. LBW rate is increasing in some Brazilian regions. Regional differences in LBW rate seem to be more associated to availability of perinatal care services than underlying social conditions.

Natural history of suspected developmental delay between 12 and 24 months of age in the 2004 Pelotas birth cohort

AIMS

To describe the incidence and persistence of suspected developmental delay (SDD) between 12 and 24 months of age and associated factors in the 2004 Pelotas Birth Cohort.

METHODS

A cohort of 4262 newborns, 3907 of whose were monitored from 12 to 24 months of life. SDD was established by Battelle Screening Developmental Inventory. The adjusted analyses were carried out using Poisson regression. Relative risks and 95% confidence intervals were calculated.

RESULTS

Incidence of SDD between 12 and 24 months of age was 1.8% (95% CI: 1.4-2.3). After the adjusted analyses, the following factors increased the risk of the incidence: Apgar 5'<7, preterm delivery, low socio-economic level, intergestational interval<or=24 months, not having been told stories in the previous 2 weeks, lack of children's books at home and male gender. A total of 390 children were positive in the 12 month (prevalence of 10%; 95% CI: 9.0-10.9). From these children, 58 remained positive up to 2 years of age, with a persistence rate of 15.6% (95% CI: 11.9-19.3). The following were factors for persistence in SDD: Apgar 5'<7, low socio-economic level, intergestational interval<or=24 months, breastfeeding duration<6 months and not having been told stories in the previous 2 weeks.

CONCLUSIONS

Easy access to children's literature and telling stories to children are inexpensive measures that may have an impact on the child's development between 12 and 24 months of life.

Birth weight and bone mass in young adults from Brazil

BACKGROUND

Birth weight is positively associated with adult bone mass. However, it is not clear if its effect is already evident in early adulthood.

OBJECTIVE

To investigate the association between birth weight, adult body size, the interaction between them and bone mass in young adults.

METHODS

Bone densitometry by DXA was performed on 496 individuals (240 men) aged 23-24 years from the 1978/79 Ribeirão Preto (southern Brazil) birth cohort, who were born and still residing in the city in 2002. Birth weight and length as well as adult weight and height were directly measured and converted to z-scores. The influence of birth weight and length, and adult weight and height on bone area (BA), bone mineral content (BMC) and bone mineral density (BMD) at the lumbar spine, proximal femur and femoral neck were investigated through simple and multiple linear regression models. Adjustments were made for sex, skin color, gestational age, physical activity level, smoking status and dietary consumption of protein, calcium and alcohol. Interaction terms between birth weight and adult weight, and birth length and adult height were tested.

RESULTS

Men in the highest tertile of birth weight distribution had greater BA and BMC at all three bone sites when compared with their counterparts in the lowest tertiles (p<0.008). For BMD, this trend was observed only in the lumbar spine. Adult weight and height were positively associated with BA and BMC at all three bone sites (p<0.05). For BMD, these associations were seen for adult weight, but for adult height an association was observed only in the lumbar spine. Birth weight retained positive associations with proximal femur BA and BMC after adjustments for current weight and height. No interaction was observed between variables measuring prenatal growth and adult body size.

CONCLUSION

Birth weight and postnatal growth are independent determinants of adult bone mass in a sample of Brazilian adults. This effect is already evident in early adulthood.

SECULAR TREND OF VERY LOW BIRTH WEIGHT RATE IN PORTO ALEGRE, SOUTHERN BRAZIL

The strong association of very low birth weight (VLBW; <1500 g) with infant mortality is well known. There are no data related to VLBW trends in Brazil although findings from some large surveys carried out in small- and medium-sized cities have demonstrated an increase in low birth weight (LBW; <2500 g) rates over the last 30 years. The aim of this study was to evaluate the secular trend of VLBW in the city of Porto Alegre, a large city in a developed area in southern Brazil, and the potential determinants of this trend during the 1990s and early 2000s. This is a registry-based study. Data were obtained from birth certificates of all live births in the city from 1994 to 2005. The variables analysed were: VLBW as the dependent variable and maternal age and schooling, type of delivery, type of hospital, number of live births, gestational age, newborn gender and unemployment rate. The incidence ratio rate (IRR) using Poisson regression was calculated to identify possible trends in VLBW rates. Poisson regressions were performed in order to assess the influence of some independent variables on VLBW. A total of 257,740 singleton newborns were delivered in the city during the period, with a steady reduction in the total number of live births per year from 23,296 in 1994 to 18,325 in 2005. The results showed a small but significant increase in VLBW (p for trend=0.049). There was a significant trend towards adequacy for gestational age per birth weight, suggesting a reduction in rates of intrauterine growth restriction (IUGR) (p<0.001). The findings showed a significant increase of 1% per year in the probability of VLBW. The main risk factors were related to VLBW mothers with low levels of schooling, public hospitals and multiparity and nulliparity. After adjustment, nulliparity remained as a significant risk factor. The interaction between type of hospital and type of delivery indicated that the probability for VLBW was 3.6 times higher (p<0.001) among those born in public hospitals by Caesarean section than those born in private hospitals by vaginal delivery. The results show that southern Brazil is going through a demographic transition characterized by a significant decrease in number of live births associated with a small increase in VLBW rates, a decrease in IUGR rates and stabilization of LBW.

Prenatal care effectiveness and utilization in Brazil

The impact of prenatal care use on birth outcomes has been understudied in South American countries. This study assessed the effects of various measures of prenatal care use on birth weight (BW) and gestational age outcomes using samples of infants born without and with common birth defects from Brazil, and evaluated the demand for prenatal care. Prenatal visits improved BW in the group without birth defects through increasing both fetal growth rate and gestational age, but prenatal care visits had an insignificant effect on BW in the group with birth defects when adjusting for gestational age. Prenatal care delay had no effects on BW in both infant groups but increased preterm birth risk in the group without birth defects. Inadequate care versus intermediate care also increased LBW risk in the group without birth effects. Quantile regression analyses revealed that prenatal care visits had larger effects at low compared with high BW quantiles. Several other prenatal factors and covariates such as multivitamin use and number of previous live births had significant effects on the studied outcomes. The number of prenatal care visits was significantly affected by several maternal health and fertility indicators. Significant geographic differences in utilization were observed as well. The study suggests that more frequent use of prenatal care can increase BW significantly in Brazil, especially among pregnancies that are uncomplicated with birth defects but that are at high risk for low birth weight. Further research is needed to understand the effects of prenatal care use for pregnancies that are complicated with birth defects.

Diferenciais intra-urbanos de peso ao nascer no município de São Paulo

OBJETIVO: Identificar diferenciais intra-urbanos e fatores de risco na prevalência de baixo peso ao nascer. MÉTODOS: Foram utilizadas as informações das declarações de nascido vivo de mães residentes no município de São Paulo, obtidos do Sistema de Informação de Nascidos Vivos e Fundação Seade, para o período de 2002 e 2003, totalizando 368.980 nascidos vivos. Os endereços foram geo-referenciados em setores censitários e classificados em seis grupos de vulnerabilidade segundo o Índice Paulista de Vulnerabilidade Social. Para identificação dos possíveis fatores de risco empregou-se análise de regressão logística. RESULTADOS: Observou-se tendência de crescimento da prevalência de baixo peso ao nascer com aumento da vulnerabilidade (de 6,8% a 8,1%). Houve diferenças significativas entre os grupos quanto às características maternas, assistência pré-natal e da proporção de nascimentos de não pré-termo de baixo peso. No grupo de baixo peso não pré-termo, proxy da presença de retardo do crescimento intra-uterino, residir em áreas vulneráveis (1,29;1,17-1,43) e características socioeconômicas maternas desaforáveis, como mães adolescentes (1,13;1,04-1,22), baixa escolaridade (1,26;1,17-1,35) e elevada paridade (1,10;1,01-1,20) foram fatores de risco, assim como mães idosas (1,38;1,30-1,47), e sem companheiro (1,15;1,11-1,20). A ausência de pré-natal apresentou o maior risco de baixo peso para nascimentos de pré-termo (3,39;2,86-4,02) e não pré-termo (2,12;1,87-2,41). Houve redução de risco de baixo peso com o aumento de consultas de pré-natal para nascimentos de pré-termo e não pré-termo. CONCLUSÕES: Há diferenças de prevalência de baixo peso ao nascer segundo grupos de vulnerabilidade. A assistência pré-natal mostrou-se desigual segundo grupos de vulnerabilidade e seu elevado risco para o baixo peso ao nascer indica a importância de ampliar o acesso e qualidade dos serviços de saúde.

Maternal-child health in Pelotas, Rio Grande do Sul State, Brazil: major conclusions from comparisons of the 1982, 1993, and 2004 birth cohorts

Important changes were observed in maternal characteristics, health care indicators, and child health during the 22 years covered by the three population-based birth cohort studies conducted in the city of Pelotas, Southern Brazil. Maternal education levels improved, cigarette smoking during pregnancy was reduced, and birth intervals became longer. Also, there were more single mothers, and maternal obesity increased. Coverage of antenatal and delivery care by professionals improved, but inductions and caesarean sections increased markedly, the latter accounting for 45% of deliveries in 2004. With regard to child health, the reductions in neonatal and infant mortality rates were modest, and the significant increase in preterm births--14.7% of all births in 2004--appears to have colluded with this stagnation. Other infant health indicators, such as immunization coverage and breastfeeding duration, showed improvements over the period. Regarding infant nutrition, malnourishment at age 12 months decreased, but the prevalence of overweight was higher in 2004. The existence of three population-based birth cohorts using comparable methodology allowed for the study of important secular trends in maternal and child health.

Preterm births, low birth weight, and intrauterine growth restriction in three birth cohorts in Southern Brazil: 1982, 1993 and 2004

Three birth cohort studies from 1982, 1993 and 2004, in Pelotas, Southern Brazil provided the data for this study of trends in preterm births, low birth weight, and intrauterine growth restriction. We found a slight increase in the period in the low birth weight prevalence from 9% to 10%. Intrauterine growth restriction decreased from 14.8% in 1982 to 9.4% in 1993, and subsequently increased to 12% in 2004, whereas preterm births increased markedly, from 6.3% in 1982 to 14.7% in 2004. This striking increment could not be explained by changes in maternal characteristics, as mothers in 2004 were heavier, smoked less during pregnancy and attended antenatal clinics more often and earlier than those of previous cohorts. However, pregnancy interruptions due either to caesarean sections or to inductions significantly increased. Caesareans increased from 28% in 1982 to 45% in 2004, and inductions were 2.5% in 1982 but 11.1% in 2004. The increase in preterms could be partially explained by the growing number of pregnancy interruptions, but there must be other causes since this increase was also observed among babies born by non-induced vaginal deliveries.

Associated factors and consequences of late preterm births: results from the 2004 Pelotas birth cohort

Although neonatal and infant mortality rates have fallen in recent decades in Brazil, the prevalence of preterm deliveries has increased in certain regions, especially in the number of late preterm births. This study was planned to investigate: (1) maternal antenatal characteristics associated with late preterm births and (2) the consequences of late preterm birth on infant health in the neonatal period and until age 3 months. A population-based birth cohort was enrolled in Pelotas, Southern Brazil, in 2004. Mothers were interviewed and the gestational age of newborns was estimated through last menstrual period, ultrasound and Dubowitz's method. Preterm births between 34 and 36 completed weeks of gestational age were classified as late preterm births. Only singleton live births from mothers living in the urban area of Pelotas were investigated. Three months after birth, mothers were interviewed at home regarding breast feeding, morbidity and hospital admissions. All deaths occurring in the first year of life were recorded. A total of 447 newborns (10.8%) were late preterms. Associations were observed with maternal age <20 years (prevalence ratio [PR] 1.3 [95% CI 1.1, 1.6]), absence of antenatal care (PR 2.4 [1.4, 4.2]) or less than seven prenatal care visits, arterial hypertension (PR 1.3 [1.0, 1.5]), and preterm labour (PR 1.6 [1.3, 1.9]). Compared with term births, late preterm births showed increased risk of depression at birth (Relative risk [RR] 1.7 [1.3, 2.2]), perinatal morbidity (RR 2.8 [2.3, 3.5]), and absence of breast feeding in the first hours after birth (PR 0.9 [0.8, 0.9]). RRs for neonatal and infant mortality were, respectively, 5.1 [1.7, 14.9] and 2.1 [1.0, 4.6] times higher than that observed among term newborns. In conclusion, in our setting, the prevention of all preterm births must be a priority, regardless of whether early or late.

Factors associated with infant and adolescent mortality

Few studies have described factors associated with infant and adolescent mortality since birth. We report here mortality during a 20-year period in a birth cohort from Ribeirão Preto in order to identify birth variables that influenced mortality among infants and children between 10 and 19 years of age, the main causes of death, and the influence of social inequality at birth on death. Mothers were interviewed shortly after delivery. Social, biological and demographic information was collected, and mortality up to 19 years of age was investigated in registry systems. Of the 6748 liveborn singletons born in the municipality from 1978 to 1979, 343 died before or when 19 years of age were completed. Most of the cohort mortality (74.9%) occurred during the first year of life and 19.6% occurred from 10 to 19 years. Mortality was higher among boys. Preterm birth (hazard ratio, HR = 7.94) and low birth weight (HR = 10.15) were strongly associated with infant mortality. Other risk factors for infant mortality were: maternal age (3)35 years (HR = 1.74), unskilled manual occupation of family head (HR = 2.47), and for adolescent mortality: unskilled manual occupation of family head (HR = 9.98) and male sex (HR = 6.58). "Perinatal conditions" were the main causes of deaths among infants and "external causes" among adolescents, especially boys. Socioeconomic factors at birth, represented by occupation, influenced adolescent mortality due to external causes, which was higher among boys (7:1). The influence of social inequality at birth on death, measured by occupation, was greater in adolescence than in infancy.

Risk factors for intrauterine growth restriction: a comparison between two Brazilian cities

In Brazil, similar intrauterine growth restriction (IUGR) rates were observed between cities with distinct levels of socioeconomic development, challenging the current knowledge that higher rates of IUGR would necessarily be observed in poorer areas than in wealthier ones. Ribeirão Preto, a city located in the most developed area in Brazil, showed an IUGR rate of 18% in 1994, whereas this rate was 18.5% in 1997/1998 in São Luis, located in one of the poorest areas in the country. The objective of this study was to compare risk factors for IUGR in these two cities and to identify factors that are responsible for this unexpected lack of difference between the rates. Using data from two birth cohorts, including 2839 neonates who were from Ribeirão Preto and born in 1994 and 2439 neonates who were from São Luis and born in 1997/1998, a multivariable analysis was conducted to assess changes in the risk for IUGR in the poorer city compared with the wealthier one in a combined model, adjusting for some risk factors for IUGR. The wealthier city showed higher rates of maternal smoking, attendance in the private sector, and obstetric interventions than the less developed one. Differences in maternal smoking and obstetric interventions were possibly responsible for the similarity of the rates between cities. It seems that early detection of IUGR followed by cesarean section in the wealthier city is associated with increased low birth weight and IUGR rates but reduced stillbirth and infant mortality rates.