Background: Birth weight is one of the most important determinants of perinatal well -being and survival. It may be influenced by socioeconomicstatus among other factors.Objective: To evaluate the influence of parental socioeconomic status on birth weight distribution of term infantsPatients and Methods: Consecutive singleton, term newborns and their parents were recruited. Socioeconomic status was determined from parental education and occupation. Neonatal anthropometry was recorded soon after birth. The relationship between neonatal anthropometry and parental socioeconomic status was evaluated.Results: The mean birth weight of the 280 newborns was 3180g + 501 with a range of 1800g to 5000g. Most babies (181; 64.7%) weighed between 2500g and 3490g while 5.7% weighed less than 2500g and 20 (7.1%) weresmall for gestational age. Most parents (196; 70%) were in the upper classes I and II, 69 (24.6%) were in class III while 15 (5.4%) were in classes IV and V. Babies in the socioeconomic classes IV and V had significantly lower mean birth weight than babies in each of classes I, II and III (p = 0.005, 0.006 and 0.04 respectively). High maternal educationand paternal occupation were associated with significantly higher mean birth weights (p = 0.007, 0.018 respectively). The low birth weight rate was significantly higher in the lower social classes III to V compared to the two upper classes (10.7% vs. 3.57%;, p = 0.022.Conclusion: Disadvantaged socioeconomic status was associated with lower mean birth weights with maternal education and paternal occupation exerting the higher influences.Key words: Socioeconomic Status, Birth weight, maternal education, paternal occupatio

Kehinde, OA

Njokanma, OF

Olanrewaju, DM

English

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                 ORIGINAL Niger J Paed 2013; 40 (3) : 299 –302 Kehinde OA Njokanma OF Olanrewaju DM Parental socioeconomic status and birth weight distribution of Nigerian term newborn babies Accepted: 17th March 2013  Kehinde OA  Njokanma OF Department of Paediatrics Lagos State University  College of Medicine Ikeja, Lagos Nigeria  Email: honeyplus04@yahoo.com Tel: +234803 713 1974  Olanrewaju DM Department of Paediatrics,  Olabisi Onabanjo University Teaching  Hospital, Sagamu (      )DOI:http://dx.doi.org/10.4314/njp.v40i3,20 Abstract  Background: Birth weight is one of the most impor-tant determinants of perinatal well-being and survival. It may be influenced by socioeconomic status among other factors. Objective: To evaluate the influ-ence of parental socioeconomic status on birth weight distribution of term infants Patients and Methods: Consecu-tive singleton, term newborns and their parents were recruited. So-cioeconomic status was deter-mined from parental education and occupation. Neonatal anthro-pometry was recorded soon after birth. The relationship between neonatal anthropometry and pa-rental socioeconomic status was evaluated.  Results: The mean birth weight of the 280 newborns was 3180g + 501 with a range of 1800g to 5000g. Most babies (181; 64.7%) weighed between 2500g and 3490g while 5.7% weighed less than 2500g and 20 (7.1%) were small for gestational age. Most parents (196; 70%) were in the upper classes I and II, 69 (24.6%) were in class III while 15 (5.4%) were in classes IV and V. Babies in the socioeconomic classes IV and V had significantly lower mean birth weight than babies in each of classes I, II and III (p = 0.005, 0.006 and 0.04 respec-tively). High maternal education and paternal occupation were asso-ciated with significantly higher mean birth weights (p = 0.007, 0.018 respectively). The low birth weight rate was significantly higher in the lower social classes III to V compared to the two upper classes (10.7% vs. 3.57%;, p = 0.022. Conclusion: Disadvantaged socio-economic status was associated with lower mean birth weights with maternal education and pater-nal occupation exerting the higher influences.  Key words: Socioeconomic Status, Birth weight, maternal edu-cation, paternal occupation Introduction  Birth weight is important for assessing intrauterine growth and a very important predictor of neonatal survival. 1 Thus several factors affecting fetal growth also impact on neonatal survival. Some of these factors exert direct effects on fetal growth while the effects of other factors are indirect. Direct influences which are exerted include intrinsic fetal factors like congenital malformations and environmental factors like antenatal medical problems. One very important indirect influence is the socio-economic status which may affect fetal growth through its effects on maternal nutritional status, maternal he lth-seeking behaviour and occasionally, disease pattern in pregnancy.2, 3 In this regard; some clinical studies have identified maternal educational level4 and parental occu-pation5 as significant determinants of birth weight. There however, has not been sufficient evaluation of effects of socio-economic factors on the birth weight pattern of Nigerian babies. The need for such studies is especially relevant in the light of increasing poverty level among Nigerians.   The current study therefore aims to examine the rela-tionship between parental socioeconomic class and in-fants’ birth weight among Nigerian singleton term ba-bies.    Subjects and Methods  The study was carried out at the Olabisi Onabanjo  University Teaching Hospital (O.O.U.T.H) and the  Medytop Specialist Hospital (M.S.H) both in Sagamu between July and December 2005. Sagamu is a semi-urban town located between Lagos and Ibadan, two  major cities in south-western Nigeria. OOUTH is a 201-bed tertiary care hospital providing specialist obstetric and neonatal care. The average delivery rate is about 600 a year.  The Medytop Specialist Hospital (MSH) is a 40-bed private hospital with a bias for obstetric  services. The average delivery rate for the hospital is 240 per year. The two hospitals were chosen for the study because they have the busiest public (OOUTH) and private (MSH) obstetric services in Sagamu and they serve patients from all socioeconomic strata of the community. Two hundred and eighty consecutive sin-gleton term, newborn babies – 167 from OOUTH and 113 from MSH – and their consenting parents were  recruited. Data was obtained on parental educational attainment and occupation and these were used to deter-mine family’ socio-economic classes using the method recommended by Oyedeji.6 Stratification was from so-cioeconomic class 1 (the most advantaged class) to classV (the most disadvantaged). The anthropometric pa-rameters of the babies were also recorded using stadard techniques. Gestational age was determined using the Ballard score, while appropriateness of birth weight for gestation was determined using the standards of Lubchenco et al7. Data analysis was done using Micro-soft Excel software enhanced by Megastat statistical package. The mean and standard deviation of continuous variables were derived. Tests of statistical signifcance included Student t-test, analysis of variance (ANOVA) and chi-square tests. In all analyses, probability values less than 0.05 were  accepted as statistically significant.     Results  Two hundred and eighty (58.3%) of the 480 total deliv-eries were recruited into the study. These 280 babies comprised 142 (50.7%) males and 138 (49.3%) females giving a male-to-female ratio of approximately 1:1. Ges-tational age ranged from 37 to 42 weeks with a mean of 39.34 weeks + 1.03 and birth weight ranged from 1800g to 5000g with a mean of 3180g + 501. Analysis of pa-rental educational status (Table1) revealed that most of the fathers (90.7%) and mothers (86.1%) had at leassenior secondary education. Analysis of data on occupa-tion shows that a high proportion of the mothers (73.5%) and fathers (96.4%) were skilled. The distribution of the parents into social classes was as follows: class I (71; 25.4%), class II (125; 44.6%), class III (69; 24.6%), class IV (13; 4.6%) and class V (2; 0.7%) respectivly.   Table 2 shows the birth weight distribution of the babies in relation to parental socioeconomic classification. Most of the babies (181; 64.7%) weighed between 2500g and 3490g while 5.7% were low-birth-weight (LBW). All the 16 LBW babies were also small-for-gestational-age (SGA). Male babies weighed signifi-cantly more than their female counterparts (3276g ± 504 Vs 3080g ± 480; (z = 3.24, p = 0.012). Of the 22 babies with high birth weight (>4000g), 17 (77.3%) were socioeconomic classes I and II. On the other hand, 56.3% of LBW babies were in classes III to V. The LBW rate in the upper social classes I and II was significantly lower than that of the lower social classes (III to V) – (3.57% Vs 10.7%; Fisher exact test = 5.57, p = 0.022)  Table 1: Educational attainments and occupation of parents                                Table 3 shows that mean birth weight was inversely related to socioeconomic advantage. With specific refer-ence to education, mothers with tertiary education hadheavier babies than those with senior secondary and those with the less than senior secondary education in that order (3269 ± 454g Vs 3135 ± 494g Vs 3004 ± 615g respectively: F = 5.07, p = 0.007). Similar findings were also recorded with respect to paternal education l attainment (3222 ± 449g Vs 3171 ± 506g Vs 2931 ± 725g respectively: F = 3.91, p = 0.021).  Table 4 illustrates that the maternal occupation had no significant impact on the mean birth weight. On the other hand, increasing paternal occupational status was associated with an increasing mean birth weight  (p = 0.018).   Mothers Fathers   no % no % Educational attainment         Tertiary Education 133 47.5 174 62.1 Senior School Certificate 108 38.6 80 28.6 Junior School Certificate 30 10.7 20 7.1 Primary School Certificate 8 2.9 5 1.8 No Formal Education 1 0.4 1 0.4 Occupation         Senior civil servant/Businessman/         Contractor 58 20.7 103 36.8 Intermediate grade civil servant/         Senior school teacher 86 30.7 116 41.4 Junior school teacher/Driver/Artisan 62 22.1 51 18.2 Petty trader 50 17.9 5 1.8 Unemployed or fulltime housewife 24 8.6 5 1.8 Total 280 100.0 280 100.0   Birth weight groups gm n (% total) Socioeco-nomic Class   <2500 2500 - 2999 3000 - 3499 3500 - 3999   ≥ 4000   Total I 3 (4.2) 16 (22.5) 26 (36.6) 23 (32.4) 3 (4.2) 71 (100.0) II 4 (3.2) 41 (32.8) 42 (33.6) 24 (19.2) 14 (11.2) 125 (100.0) III 6 (8.7) 21 (30.4) 26 (37.7) 12 (17.4) 4 (5.8) 69 (100.0) IV 2 (15.4) 3 (23.1) 5 (38.5) 2 (15.4) 1 (7.7) 13 (100.0) V 1 (50.0) 1 (50.0) 0 (0.0) 0 (0.0) 0 (0.0) 2 (100.0) Total 16 (5.7) 82 (29.3) 99 (35.4) 61 (21.8) 22 (7.8) 280 (100.0) Table 2: Birth weight distribution in relation to socioeconomic classification of parents 300 Table 3: Mean birth weight in relation to socioeconomic class F = 4.89, p = 0.003 Social classes IV and V were combined because the la ter had very few (2) subjects  Z-test comparison was with Social class IV/V   Table 4: Mean birth weight in relation to parental occupation F = 1.33, p = 0.258 (Maternal) F =3.42, p =0.018 (Paternal)     Discussion  It is worthy of note that most of the mothers had at le st secondary education, which had a significant positive effect on the birth weight. This is a positive report f r the United Nations Development Goal numbers 2 and 3 which seek universal basic education and female em-powerment in all fields including education. The finding was similar to an earlier report from Ibadan, south-western Nigeria8 and Iran 4 In the latter study, Maddah and Karrandish found that the mother's educational level may be considered as the most important determinant of birth weight in that population. This finding was cor-roborated by Mascie-Taylor3 and Ebomoyi et al9.  In the light of the relatively high level of educational attainment, it is not surprising that a large percentage of the parents were skilled. This would mean that more financial resources are likely to be available to the fam-ily and consequently, an improvement in socioeconomic status. This may also explain the concentration of HBW babies in the upper classes in this study since mothers in those classes are likely to be more empowered, have access to more health information and services and be at less risk of pregnancy-related problems which often have nutritional and infectious etiology. Therefore, they may have the opportunity of better fetal growth com-pared to mothers in the lower classes who are probably not as highly educated. The caveat however, is that given the various perinatal problems of HBW babies like mechanical and asphyxial injuries,10 it is imperative to closely monitor mothers in the upper socioeconomic classes for possible fetal macrosomia.  It was noted that the influence of maternal education l attainment was stronger than that of the father. On the other hand, Paternal, but not maternal occupation played a significant role in birth weight. The latter findi g is similar to that obtained by Chia and Lee5, in an earlier study where babies born to unemployed fathers had a higher risk of being LBW. It probably underlines the wisdom in the use of maternal education and paternal occupation in the method of socioeconomic stratification designed by Olusanya, Ezimokhai and Okpere.11  The prevalence of LBW in the study (5.7%) was re-markably lower than the previous prevalence of 16% in an earlier study carried out in this center.12 It was also lower than 12.6% reported from Enugu, southeastern Nigeria,13 24% from Bangladesh14 and 29.8% from Ne-pal, South Asia. 15 These differences may be a reflection of differences in patients’ selection and study designs. Preterms and products of multiple gestation are oftn LBW and their exclusion from this present study obvi-ously lowered the prevalence of LBW.   The birth weight of the fetus may be a reflection of the parental socioeconomic status and at le st to some ex-tent, the mother’s nutrition and health. Thus the low LBW rate in the two upper socioeconomic classes probably resulted from better maternal nutrition and health in pregnancy. An improvement in socioeconomic status was found to be responsible for higher mean birth weights in babies born to mothers in Sweden.16These mothers are also more likely to have better health seek-ing attitudes resulting in a better ANC attendance, lower incidence of pregnancy related disorders such as ane-mia and pregnancy induced hypertension. Better preg-nancy care and better nutrition during pregnancy were identified as factors for high birth weight in Nepal. 15 As part of routine antenatal care in Nigeria, expectant moth-ers are usually given iron supplementation. This had been shown to result in higher birth weights independent of other maternal nutritional factors in Zimbabwe. 17 These pregnancies may thus have a better outcome. The finding that LBW occurred more commonly among mothers in the lower socioeconomic classes was similar to findings in Brazil 18 and Botswana. 19 In both studies, the prominence of LBW in the lower socioeconomic classes was associated with poor quality of antenatal care. Unfortunately, the details of antenatal care were not examined in the present study. Therefore, the steady decline in the mean birth weight with decreasing socio-economic status obtained in the current study is similar to reports obtained from US where denial of access to Socioeconomic Class Number Mean birth weight ± SD g Z-test p-value I 71 3242 ± 428 2.91 0.004 II 125 3215 ± 487 2.78 0.005 III  69 3106 ± 529 2.05 0.040 IV/V  15 2750 ± 625 Reference group   no Birth weight Z-test p-value Maternal         Senior civil servant/ Businessman/Contractor   58   3290 ± 446   1.30   0.19 Intermediate grade civil servant/ Senior school teacher   86   3126 ± 479   0.20   0.84 Junior school teacher/Driver/Artisan 62 3222 ± 461 0.84 0.40 Petty trader 50 3135 ± 545 0.25 0.80 Unemployed or fulltime housewife 24 3096 ± 672     Paternal         Senior civil servant/ Businessman/Contractor   103   3264 ± 498   2.79   0.005 Intermediate grade civil servant/ Senior school teacher   116   3175 ± 474   2.28   0.023 Junior school teacher/Driver/Artisan 51 3071 ± 544 1.55 0.120 Petty trader/ Unemployed 8 2794 ± 456     301 quality pregnancy care and low standard of living, in form of segregation and isolation was identified as a cause of decreased birth weights in the studied popula-tion. 20        Conclusion   The present study has affirmed the strong relationship between the birth weight pattern of Nigerian babies and the parental socioeconomic status. The relatively stronger influences of maternal education and patern l occupation are noted. The link possibly lies in the access to better information and resources to support good health in pregnancy. Policies which will bring about an improvement in general conditions of living (housing, food), empowerment and improved access to health ser-vices should be targeted at families in the lower socio-economic classes. This may translate to improved birth weight in the lower social classes. The current tempo of high female education should be sustained and improved upon.     Conflict of Interest: None Funding: None   Acknowledgement   I would like to acknowledge professor L Odusoga who graciously offered the use of his facility for this study.  References  1.     Elshibly ME, Schmalisch G. The effect of maternal anthropometric characteristics and social factors on gestational age and birthweight in Sudanese newborn infants. BMC Public Health. 2008; 8: 244   2.     Voorhorst FJ, Bouter LM, Bezemor PD, Kurver PHJ. Mater-nal characteristics and expected birth weight. Eur J Obstet Gynecol Reprod Biol 1993; 50:115-122. 3.     Karim E, Mascie-Taylor CG. The association between birthweight, sociodemographic variables and maternal anthropometry in an ur-ban sample from Dhaka, Bangla-desh. Ann Hum Biol 1997; 5: 387 – 401. 4.     Maddah M, Karandish M, Moham-madpour-Ahranjani B, Neyestani TR, Vafa R, Rashidi A. Social factors and pregnancy weight gain in relation to infant birth weight: a study in public health centers in Rasht, Iran. Eur J Clin Nutr. 2005 Oct; 59: 1208 – 12. 5.     Chia SE, Lee J, Chia KS, Chan OY. Low Birth Weight In Relation To Parental Occupations- A Popu-lation-Based Registry In Singapore (1994-1998). 6.     Oyedeji GA. Socio-economic and cultural background of hospitalised children in Ilesa. Nig J Paediatr 1985;12:111. 7. Gomelia TL. Assessment of gesta-tional age, Neonatology. 4th Edi-tion Stamford Connecticut 1999. 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Hosain GM, Chatterjee N, Begum A, Saha SC. Factors associated with Low Birth Weight in Bangla-desh. J Trop Paediatr 2006; 52: 87-91.    15.   Azharya PP, Alpass F. Birth out-comes across ethnic groups of women in Nepal. Health Care Women Int 2004; 25: 40 – 54. 16.   Vagero D, Koupilova I, Leon DA, Lithell UB. Social determinants of birthweght, ponderal index and gestational age in Sweden in the 1920s and the 1980s. Acta Paedi-atr. 1999 Apr; 88(4):445-53. 17.   Mishra V, Thapa S, Retherford RD, Dai X. Effect of iron supple-mentation during pregnancy on birth weight; evidence from Zim-babwe. Food Nutri Bull 2005; 26: 338 – 47. 18.   Barros FC, Victora CG, Horta BL. Ethnicity and infant health in Southern Brazil: A birth cohort study. Int J Epidemiol 2001; 30: 1001 – 8. 19.   Letamo G, Majelantle RG. Factors Influencing Low Birth Weight and Prematurity In Botswana. J Biosoc Sci 2001; 33: 391 – 403. 20.   Bell JF, Zimmerman FJ, Almgren GR, Mayer JD, Huebuer CE. 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Parental socioeconomic status and birth weight distribution of Nigerian term newborn babies

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Parental socioeconomic status and birth weight distribution of Nigerian term newborn babies

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