Socio-economic differences among low-birthweight infants in Hungary. Results of the Cohort '18 -Growing Up in Hungary birth cohort study

Abstract

Background: As Hungary had the fifth-highest rate of low-birthweight (LBW) in the EU27 in 2020, LBW still remains a public health problem for the country.

Objective: Our goal is to examine whether LBW in Hungary is determined by the mothers' educational attainment, adjusted for other maternal characteristics (SES, health behaviour and psychological status during pregnancy) among mothers who gave birth in 2018-2019 in Hungary.

Methods: Source of data is the first and second wave of the Cohort '18 -Growing Up in Hungary longitudinal birth cohort study (n = 8185). It is based on a nationwide representative sample of pregnant women who gave birth between March 2018 and April 2019. All data were self-reported by mothers. We examined the association between maternal educational attainment and the risk of giving birth to an LBW-child (<2500g) by using logistic regression analysis. The highest educational attainment of the mother is measured by a five-value categorical variable (ISCED 97: 0-1; 2; 3C; 3-4; 5-6).

Results: 5.9% of women had LBW children. This rate is 18.0% among the lowest educated women with ISCED 97: 0-1; and it is 3.6% among the highest educated women with ISCED 97: 5-6. The adjusted predicted probabilities of LBW for these two groups of women are 13.5%, and 3.4% respectively, adjusted for household income quantiles, Roma ethnic background, residence place, smoking, alcohol consumption, and depression during pregnancy; controlled for mother's height, age at birth, parity and child's sex. Compared to women with the lowest level of education, the risk of giving birth to an LBW child decreases by 34.6% for those with the second level of education, by 60.1% for those with the third level of education, by 72.5% for those with the fourth level of education and by 77.2% for those with the highest level of education. Smoking during pregnancy significantly increases the risk of giving birth to an LBW by 54.9%. Being depressed at 7th month of pregnancy decreased the risk of giving birth to an LBW child in our sample by 13.2%, however the relationship is not significant.

Conclusion: Our analysis confirmed that maternal educational attainment has a significant impact on the risk of LBW net of by other maternal SES and health behaviour factors. Nevertheless, even after adjusting for these covariates, inequality in LBW by maternal educational attainment persists.

Fig 1. Proportion of women giving birth to a low-birthweight child, by covariates.

Note: On the map of Hungary, the yellow areas to the east and south-west indicate the less-developed NUTS2 counties as the residence place of the mother; the blue areas of western Hungary are the developed NUTS2 counties; while the central red area is the Central Hungarian region (including the capital city, Budapest). The number of cases belonging to the given categories is indicated in parentheses. The distribution of the basic sample of the Cohort ’18 Growing Up in Hungary Hungarian longitudinal birth cohort survey can be found in the survey’s technical report [, pp: 17. Table 2.]. Education: educational attainment of the pregnant women; income: equivalised household income quintiles; ethnicity: self-reported ethnic background of the mother; residence: residence place of the pregnant women; smoke: smoking during pregnancy with any frequancy; alcohol: drinking alcohol during pregnancy with any frequency; depression: the pregnant women is depressed at the 7^th month of pregnancy. Source: Cohort ‘18 –Growing Up in Hungary, Pregnancy and 6-month databases.

Fig 2. Probability of giving birth to a low-birthweight child, logistic regression analysis, odds ratios and 95% Cis.

Note: Control variables: parity, child’s sex, mother’s height and age group. Education: educational attainment of the pregnant women: 1: less than eight years of schooling (ISCED 97: 0, 1); 2: eight years of schooling (ISCED 97: 2); 3: vocational education (ISCED 97: 3C); 4: secondary education (ISCED 97: 3, 4); 5: higher education (ISCED 97: 5, 6); household income: equivalised household income quintile groups; ethnic background Roma: self-reported Roma ethnic background of the mother; less developed NUTS2 region: residence place of the pregnant women is in the less developed NUTS2 regions of Hungary; smoking during pregnancy: smoking during pregnancy with any frequency; alcohol consumption: alcohol consumption during pregnancy with any frequency; depression or depressed at 7^th month of pregnancy: the pregnant women is depressed at the 7^th month of pregnancy; SES variables: equivalised household income quantilies, ethnic background of the mother, region of the residence place of the mother; health behaviour variables: maternal smoking and alcohol consumption during pregnancy. Source: Cohort ‘18 –Growing Up in Hungary, Pregnancy and 6-month databases.

Fig 3. Adjusted predicted probabilities of giving birth to a low-birthweight child, by maternal educational attainment.

Note: Binary logistic regression analysis. Control variables: parity, sex of child, height of mother, age groups of mother. Figures on x-axis stands for the maternal educational attainment: 1: less than eight years of schooling (ISCED 97: 0, 1); 2: eight years of schooling (ISCED 97: 2); 3: vocational education (ISCED 97: 3C); 4: secondary education (ISCED 97: 3, 4); 5: higher education (ISCED 97: 5, 6). See also S3 Table. SES variables: equivalised household income quantilies, ethnic background of the mother, region of the residence place of the mother; health behaviour variables: maternal smoking and alcohol consumption during pregnancy; depression: the pregnant women is depressed at the 7^th month of pregnancy. Source: Cohort ‘18 –Growing Up in Hungary, Pregnancy and 6-month databases.

Fig 4. Risk of having a low-birthweight child by educational attainment of the mother: Comparison of France, UK and Hungary–logistic regression analysis, predicted probabilities, adjusted for parity, child’s sex and mother’s height.

Note: Model 1: baby’s sex, whether the baby is a first child, the mother’s age group, the height of the mother (meter). Educational attainment of the pregnant women: lower secondary (ISCED 97: 0, 1, 2, 3C); upper secondary (ISCED 97: 3, 4); tertiary (ISCED 97: 5, 6). Model 2: Model 1 + equivalised household income quantiles. Model 3: Model 2 + drinking and smoking during pregnancy. Only singleton births at more than 33 weeks’ gestation to mothers aged 18 or over were included in all three surveys for this comparison. Source: France: French Longitudinal Study of Children (ELFE) survey (2011); United Kingdom: Millennium Cohort Study (MCS) survey (2001) ([11]: Fig 3); Hungary: Cohort ‘18 –Growing Up in Hungary (2018–2019). See S4 Table for marginal effects of the adjusted predicted probabilities and their 95% confidence interval, for Hungarian data.