Social inequality and perinatal health: comparison of three Brazilian cohorts

Abstract

The objective of the present study was to estimate and compare social inequality in terms of three indicators, i.e., low birth weight (LBW), preterm birth (PTB) and small for gestational age (SGA) birth, in three birth cohorts. Two cohorts were from the city of Ribeirão Preto, where data were collected for all 6748 live born singletons in 1978/79 and for one third of live born singletons (2846) in 1994. The third cohort consisted of 2443 singletons born in São Luís over a period of one year (1997/98). In Ribeirão Preto, LBW and PTB rates increased in all social strata from 1978/79 to 1994. Social inequalities regarding LBW and PTB disappeared since the increase in these rates was more accelerated in the groups with higher educational level. The percentage of SGA infants increased over the study period. Social inequality regarding SGA birth increased due to a more intense increase in SGA births in the strata with lower schooling. In São Luís, in 1997/98 there was no social inequality in LBW or PTB rates, whereas SGA birth rate was higher in mothers with less schooling. We speculate that the more accelerated increase in medical intervention, especially due to the increase in cesarean sections in the more privileged groups, could be the main factor explaining the unexpected increase in LBW and PTB rates in Ribeirão Preto and the decrease or disappearance of social inequality regarding these perinatal indicators in the two cities. Correspondence

Maternal socioeconomic factors and adverse perinatal outcomes in two birth cohorts, 1997/98 and 2010, in São Luís, Brazil

“…In Pelotas, similar results from 1993 to 2004 were observed 14 . However, in São Luís, the percentage of PTB among LBW did not change significantly: from 51.1% in 1997/98 to 54.3% in 2010 (p = 0.646) 17,39 .…”

“…PTB was lower in middle-income families (> 1 and ≤ 3 minimum wages), and IUGR was associated with low education (0-4 years) and low income (≤ 1 minimum wage) 17 . In 2010 minimal socioeconomic inequality in adverse perinatal outcomes were detected because, only in the case of low birth weight, families with ≤ 1 minimum wage had a 50% higher risk of LBW.…”

“…Compared to a cohort in São Luís in 1997/98, LBW and PTB rates stayed the same in the socioeconomic groups analyzed. IUGR decreased among less educated mothers (from 14.2 to 10.4%, p = 0.007 in mothers with 5-8 years of education, from 15.3 to 8.8%, p = 0.018 in mothers with 0-4 years of education) and in mothers whose head of the family had manual unskilled jobs or were unemployed (14.8 to 9.7%, p < 0.001) 17 . The decrease in IUGR rate over the past 10 years, accompanied by a reduction in the number of growth restricted neonates in less advantaged social groups, suggested an improvement in health care and/or health conditions, especially in the lower classes, the most prevalent in this study.…”

“…In the city of Ribeirão Preto, São Paulo, Brazil, in the years 1978/79 and 1994, LBW and IUGR rates were lower in families of higher income, education, and non-manual occupations. PTB rates had the same socioeconomic pattern in 1978/79, but this difference disappeared in 1994 17 . In São Luís, Maranhão, Brazil, in 1997/98 there were no differences in LBW and PTB rates regarding schooling, income, and occupation of the head of the family.…”

“…In São Luís, Maranhão, Brazil, in 1997/98 there were no differences in LBW and PTB rates regarding schooling, income, and occupation of the head of the family. On the other hand, IUGR was more prevalent in mothers with low income and schooling 17 . In Brazil, in the year 2005, a higher proportion of term neonates with LBW were found in mothers with low education 18 .…”