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

DOI:http://dx.doi.org/10.4314/njp.v40i3,20

Accepted: 17th March 2013

Abstract Background: Birth

weight is one of the most impor-

tant determinants of perinatal well

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.

(

)

Kehinde OA

Njokanma OF

-being and survival. It may be

Department of Paediatrics

Lagos State University

College of Medicine Ikeja, Lagos

Nigeria

Email: honeyplus04@yahoo.com

Tel: +234803 713 1974

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.

Olanrewaju DM

Department of Paediatrics,

Olabisi Onabanjo University Teaching

Hospital, Sagamu

Conclusion: Disadvantaged socio-

economic status was associated

with lower mean birth weights

with maternal education and pater-

nal occupation exerting the higher

influences.

Results: The mean birth weight of

the 280 newborns was 3180g +

5

01 with a range of 1800g to

000g. Most babies (181; 64.7%)

weighed between 2500g and

3

than 2500g and 20 (7.1%) were

small for gestational age. Most

490g while 5.7% weighed less

Key words: Socioeconomic

Status, Birth weight, maternal edu-

cation, paternal occupation

Introduction

level among Nigerians.

Birth weight is important for assessing intrauterine growth₁

and a very important predictor of neonatal survival.

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 health

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

-

pregnancy. In this regard; some clinical studies have

identif₅ied maternal educational level and parental occu-

seeking beh_,₃aviour and occasionally, disease pattern in

2

4

pation 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

3

00

services. The average delivery rate for the hospital is

40 per year. The two hospitals were chosen for the

Table 1: Educational attainments and occupation of parents

2

Mothers

Fathers

no

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

no

%

Educational attainment

Tertiary Education

133

108

47.5

38.6

174

80

62.1

28.6

Senior School Certificate

Junior School Certificate

Primary School Certificate

30

8

10.7

2.9

20

5

7.1

1.8

0.4

1

13 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

No Formal Education

1

0.4

1

Occupation

Senior civil servant/Businessman/

Contractor

6

recommended by Oyedeji. Stratification was from so-

58

20.7

103

36.8

Intermediate grade civil servant/

cioeconomic class 1 (the most advantaged class) to class

V (the most disadvantaged). The anthropometric pa-

rameters of the babies were also recorded using standard

techniques. Gestational age was determined using the

Ballard score, while appropriateness of birth weight for

gestation was determined using the standards of

Senior school teacher

Junior school teacher/Driver/Artisan

86

62

30.7

22.1

116

51

41.4

18.2

Petty trader

Unemployed or fulltime housewife

Total

50

24

280

17.9

8.6

100.0

5

280

1.8

100.0

7

Lubchenco et al . 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 significance

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

3

9.34 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 least

senior 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;

2

5.4%), class II (125; 44.6%), class III (69; 24.6%),

class IV (13; 4.6%) and class V (2; 0.7%) respectively.

Table 3 shows that mean birth weight was inversely

related to socioeconomic advantage. With specific refer-

ence to education, mothers with tertiary education had

heavier 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 educational

attainment (3222 ± 449g Vs 3171 ± 506g Vs 2931 ±

725g respectively: F = 3.91, p = 0.021).

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

2

500g 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

(

=

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).

III to V) – (3.57% Vs 10.7%; Fisher exact test = 5.57, p

0.022)

3

01

Table 3: Mean birth weight in relation to socioeconomic class

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 problems₁o₀ f HBW babies

like mechanical and asphyxial injuries, it is imperative

to closely monitor mothers in the upper socioeconomic

classes for possible fetal macrosomia.

Socioeconomic

Class

Number Mean birth

weight ± SD g

Z-test

p-value

I

II

71

125

3242 ± 428

3215 ± 487

2.91

2.78

0.004

0.005

III

IV/V

69

15

3106 ± 529

2750 ± 625

2.05

Reference group

0.040

F = 4.89, p = 0.003

Social classes IV and V were combined because the latter had very

few (2) subjects

Z-test comparison was with Social class IV/V

It was noted that the influence of maternal educational

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 finding is

Table 4: Mean birth weight in relation to parental occupation

no

Birth weight

Z-

test

p-value

5

similar to that obtained by Chia and Lee , in an earlier

Maternal

Senior civil servant/

Businessman/Contractor

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 stra₁₁tification

designed by Olusanya, Ezimokhai and Okpere.

58

86

3290 ± 446

3126 ± 479

1.30

0.20

0.19

0.84

Intermediate grade civil

servant/

Senior school teacher

Junior school teacher/

Driver/Artisan

62

3222 ± 461

0.84

0.25

0.40

0.80

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. It was also

lower tha₃ n 12.6% reported from Enugu, southeastern

1 14

Nigeria, 24% from Bangladesh and 29.8% from Ne-

15

Petty trader

Unemployed or fulltime

housewife

50

24

3135 ± 545

3096 ± 672

12

Paternal

Senior civil servant/

Businessman/Contractor

pal, South Asia. These differences may be a reflection

of differences in patients’ selection and study designs.

Preterms and products of multiple gestation are often

LBW and their exclusion from this present study obvi-

ously lowered the prevalence of LBW.

103

116

3264 ± 498

3175 ± 474

2.79

2.28

1.55

0.005

0.023

0.120

Intermediate grade civil

servant/

Senior school teacher

Junior school teacher/

Driver/Artisan

51

8

3071 ± 544

2794 ± 456

The birth weight of the fetus may be a reflection of the

parental socioeconomic status and at least 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

Petty trader/ Unemployed

F = 1.33, p = 0.258 (Maternal)

F =3.42, p =0.018 (Paternal)

Discussion

16

weights in babies born to mothers in Sweden. These

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 anae-

mia and pregnancy induced hypertension. Better preg-

nancy care and better nutrition during pregnancy w₁₅ere

identified as factors for high birth weight in Nepal. 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 independen₁₇t

of other maternal nutritional factors in Zimbabwe.

These pregnancies may thus have a better outcome. The

finding that LBW occurred more commonly among

mothers in the lower₁s₈ocioeconomic cl₁a₉sses was similar

to findings in Brazil and Botswana. 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

It is worthy of note that most of the mothers had at least

secondary education, which had a significant positive

effect on the birth weight. This is a positive report for

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-

8

4

western Nigeria and Iran 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 finding₉was cor-

3

roborated by Mascie-Taylor and Ebomoyi et al .

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

3

02

quality pregnancy care and low standard of living, in

form of segregation and isolation was identified as a

cause₂₀of decreased birth weights in the studied popula-

tion.

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.

Conclusion

Conflict of Interest: None

Funding: None

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 paternal

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,

Acknowledgement

I would like to acknowledge professor L Odusoga who

graciously offered the use of his facility for this study.

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