|Year : 2013 | Volume
| Issue : 1 | Page : 57-62
Growth parameters at birth of babies born in Gampaha district, Sri Lanka and factors influencing them
Priyantha J Perera1, Nayomi Ranathunga2, Meranthi P Fernando1, Tania D Warnakulasuriya3, Rajitha A Wickremasinghe4
1 Department of Paediatrics, Faculty of Medicine, University of Kelaniya, Ragama, Colombo, Sri Lanka
2 Department of Paediatrics, Lady Ridgway Hospital for Children, Colombo, Sri Lanka
3 Department of Physiology, Faculty of Medicine, University of Kelaniya, Ragama, Sri Lanka
4 Department of Public Health, Faculty of Medicine, University of Kelaniya, Ragama, Sri Lanka
|Date of Web Publication||2-Aug-2013|
Priyantha J Perera
Department of Paediatrics, Faculty of Medicine, University of Kelaniya, Ragama
Background: Growth parameters at birth are important for clinical decision-making. In Sri Lanka, the data from the World Health Organization (WHO) Multicentre Growth Reference Study (MGRS) are used to interpret these measurements.
Materials and Methods: A descriptive cross-sectional study was conducted between September and October 2010 in hospitals of Gampaha district, Sri Lanka. The weight, length and head circumference of all normal-term babies born in the Gampaha district during this period were measured within 8 h of birth using standard techniques. Measurements were taken by medical graduates trained and supervised by a consultant paediatrician. Socio-demographic data were obtained using an interviewer-administered questionnaire.
Results: Of the 2215 babies recruited, 1127 were males. The mean birth weight, mean length and mean head circumference at birth were 2.92 kg, 49.1 and 33.6 cm, respectively. Boys weighed and measured more than girls in all parameters, but the differences were not statistically significant. Growth parameters of babies included in this study deviated from that in the MGRS data. Mean values of MGRS data were between 75th and 90th centiles of this study population. Birth order, family income and maternal education were significantly (P < 0.01) associated with growth parameters. Contrary to common belief, growth parameters continued to increase progressively up to 41 weeks. Maternal age less than 20 years or more than 35 years was negatively associated with birth weight (P < 0.01).
Conclusions: Growth parameters of new-born babies deviated significantly from the values of the MGRS data. Growth characteristics of one population may not be applicable to another population due to variations in maternal, genetic and socio-economic factors. Using growth charts not applicable to a population will result in wrong interpretations.
Keywords: Birth weight, growth parameters, head circumference, length, new born, Sri Lanka
|How to cite this article:|
Perera PJ, Ranathunga N, Fernando MP, Warnakulasuriya TD, Wickremasinghe RA. Growth parameters at birth of babies born in Gampaha district, Sri Lanka and factors influencing them. WHO South-East Asia J Public Health 2013;2:57-62
|How to cite this URL:|
Perera PJ, Ranathunga N, Fernando MP, Warnakulasuriya TD, Wickremasinghe RA. Growth parameters at birth of babies born in Gampaha district, Sri Lanka and factors influencing them. WHO South-East Asia J Public Health [serial online] 2013 [cited 2019 Oct 18];2:57-62. Available from: http://www.who-seajph.org/text.asp?2013/2/1/57/115845
| Introduction|| |
Growth parameters at birth depend on intrauterine growth, which is affected by many factors such as intra-uterine environment, physical and mental well-being of the mother, maternal nutrition and genetic factors.  The weight, length and head circumference of babies are measured at birth in view of their clinical significance. Small for gestational age (SGA) remains one of the most important predictors of the outcome of the babies' health.  SGA is commonly defined as a baby with birth weight less than 10 th centile for a given gestational age.  SGA babies are divided as symmetrically or asymmetrically growth-restricted babies, depending on their length and head circumference. This distinction has practical implications, as complications expected in these two categories of babies are different.  For a meaningful interpretation of growth parameters, it is important that appropriate reference standards are available for comparison. At present, growth charts developed by World Health Organization (WHO), based on results of a Multicentre Growth Reference Study (MGRS), are used in Sri Lanka. However, MGRS included children brought up under optimal conditions and reflects growth patterns of babies with maximum growth potentials.  MGRS was based on the theory that growth of children from birth to 5 years depends mainly on nutrition, feeding practices, environment and healthcare without consideration of other factors such as genetics or ethnicity. 
Two previous studies have been conducted in Sri Lanka to determine the average birth weight, but none focused on all three growth parameters. One study performed in the Mawanella area, in the Kegalle district, had a small sample size,  while the other study performed in the Gampaha district had a large sample size but the weights were measured by ward staff.  Measurements taken by ward staff in this study were not supervised or verified for accuracy.
The present study was conducted to determine the growth parameters at birth for a cohort of Sri Lankan children and to assess the accuracy of using MGRS data to interpret growth of Sri Lankan children. Factors influencing growth parameters at birth were also studied.
| Materials and Methods|| |
Sri Lanka is a low-middle income country, with impressive health statistics such as a maternal mortality ratio of 33.4 per 100 000 live births  and a neonatal mortality rate of 10 per 1000 live births.  More than 99% of deliveries take place in hospitals. Sri Lanka is divided into 25 administrative districts and Gampaha district is the second most populous district with an estimated mid-year population of 2 066 096, which is approximately 12% of the total Sri Lankan population.  Gampaha district had 9.2% of poor households in 2002.  There are four large government hospitals and many private hospitals within the district, but only six private hospitals have facilities for obstetric care at delivery. Antenatal care to pregnant mothers is provided by many antenatal clinics scattered throughout the district, but delivery of babies take place mainly in the above-mentioned hospitals.
This was a descriptive cross-sectional study conducted between September and October 2012. All four large government hospitals and the six private hospitals referred earlier were selected for the study.
Permission to conduct the study was obtained from health authorities of the district and the heads of the hospitals where the study was conducted. All babies born in these hospitals during the study period, following a period of gestation (POG) of ≥37 weeks, were recruited in the study. Babies with uncertain POG, antenatally diagnosed intrauterine growth restriction, chromosomal abnormalities and major congenital abnormalities were excluded from the study. Babies of mothers who had diabetes mellitus, hypertension, multiple pregnancies or any other major medical problem were also excluded.
The weight, length and head circumference were measured within 8 h of birth. Standardized beam balance scales were used to measure birth weight. Scales were standardized weekly during the study period. Weight was recorded to the second decimal in kilograms. Foldable infantometers were used to measure the body length using standard techniques. Two investigators were assigned to each of the large government hospital; one investigator positioned the baby correctly and the other took the measurement. Occipital-frontal circumference (OFC) was measured using a non-stretchable, plastic tape using standard techniques. In babies with significant moulding and caput succedaneum, measurement of OFC was delayed until they settled. OFC and length were recorded to the first decimal in centimetres.
Data collection was done by trained medical graduates. The training including measuring growth parameters and data collection was conducted by the principal investigator.
Descriptive statistics and frequency tabulations were generated using IBM SPSS Statistics version 16. Independent sample t-test and analysis of variance (ANOVA) were used to compare means.
Ethical approval to conduct the study was obtained from the Ethical Review Committee of the Faculty of Medicine, University of Kelaniya. Informed written consent was obtained from the mothers to include their babies in the study. Aseptic precautions were taken during handling of babies. Babies who were found to have any problems were referred for appropriate action.
| Results|| |
Of the 2215 babies (1127 males and 1088 females) included in the study, 80 were born in private hospitals and the rest in government hospitals. Parents of 166 babies were resident outside the Gampaha district. All babies born during the study period who fulfilled the inclusion criteria were recruited into the study, except for eight whose mothers refused consent.
As expected with large numbers, birth weight, length and head circumference were normally distributed.
The mean birth weight of all babies was 2.93 kg, while the mean length was 49.1 cm and the mean head circumference was 33.6 cm. All three parameters were higher in boys, but the differences between the sexes were not statistically significant [Table 1].
Birth weight ranged 1.89-4.25 kg for boys and 1.89-4.20 kg in girls. The range of birth length was 41.0-53.2 cm for boys and 40.7-53.0 cm for girls. The range of head circumference was 30.1-36.2 cm for boys and 30.0-36.1 cm for girls. The growth parameters at birth by sex are summarized in [Table 1].
Variation in growth parameters at birth by selected socio-economic characteristics are given in [Table 2].
|Table 2: Variation in growth parameters at birth by selected socio-economic factors|
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Birth weight increased with an increase in family income (P < 0.001). The majority of mothers were not employed. The employment status of the mother was not associated with growth parameters at birth. The majority of mothers were educated up to grades 6-11. Both birth weight (P < 0.001) and head circumference (P = 0.002) increased with an increase in maternal education.
Growth parameters at birth by selected maternal factors are summarized in [Table 3].
|Table 3: Variation in the growth parameters at birth by selected maternal factors|
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Up to the 34 years of age, all three growth parameters at birth were positively correlated to maternal age; however, birth weight was the only significant parameter (P < 0.001). Beyond 35 years, growth parameters decreased with age.
The mean birth weight of babies born to teenage mothers (mothers <20 years) was significantly lower (P < 0.001) than the mean birth weight of babies born to mothers ≥20 years (2.78 kg vs. 2.93 kg). The length of babies born to teenage mothers at birth was significantly less than that of babies born to mothers >20 years of age (P = 0.024) [Table 3].
Fifty-eight percent of the babies were born following a POG of >39 weeks. All three growth parameters increased with advancing POG (P < 0.001). The second and higher-order children were heavier than the first-born children (P < 0.001) [Table 3].
The 10 th centiles of the study population for birth weight, length and head circumference were 2.45 kg, 46.4 and 32.2 cm for males and 2.39 kg, 45.9 and 32.0 cm for females, respectively. In this study, 29%, 22% and 17% of children fell below the 10 th centiles of the MGRS for birth weight, length and head circumference. Similarly, 1%, 3% and 1% of babies of this study were >90 th centile of the MGRS for birth weight, length and head circumference [Table 4].
[Table 5] gives the classification of babies by the centiles of the MGRS study and the centiles of this study. Based on the centiles of this study, 378 babies had at least one parameter below the 10 th centile. Based on the MGRS study, 828 babies had at least one parameter below the 10 th centile.
|Table 5: Classification of subjects using centiles of this and the MGRS study using all three growth parameters|
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| Discussion|| |
All three growth parameters at birth were higher in boys than in girls, as in previous studies,  but the differences were not statistically significant. As with most biological parameters with large samples, birth weight, length and head circumferences were normally distributed in boys, girls and in the total sample. In the MGRS, the mean birth weights for boys and girls were 3.3 and 3.2 kg, respectively, as compared with 2.97 kg and 2.89 kg for boys and girls in this study. In this study population, the mean birth weights of 3.3 kg for boys and 3.2 kg for girls in the MGRS study fell between the 75 th and 90 th centiles. The mean length of both boys (49.8 cm) and girls (49.1cm) and the mean head circumference of girls (33.8 cm) in the MGRS was between the 50 th and 75 th centiles of these parameters in this study.
As there is a wide discrepancy between data from MRGS and this study, it can be postulated that using MGRS data to interpret growth parameters of Sri Lankan babies at birth is inappropriate, as it may result in an underestimation of growth. Results of this study highlight the importance of each country to have its own growth charts to interpret growth parameters, rather than relying on growth charts based on a different population.
Our data are similar to previous studies performed in Sri Lanka. ,
When growth charts are developed, the children with maximum growth potentials are considered. In this study, babies with any condition that influence intrauterine growth were excluded. Therefore, growth parameters described in this study are for normal-term babies of the Gampaha district of Sri Lanka. By including babies born in private hospitals, babies of a higher socio-economic stratum in the community were also included. The Gampaha district ranks second out of all districts of Sri Lanka with regard to socio-economic status of the population.  As socio-economic factors play a significant role in determining the growth parameters at birth, the values for the entire country would probably be less than those reported here.
New-born babies who are SGA and large for gestational age (LGA) can have many complications. SGA babies with asymmetric growth retardation are more prone to hypoglycaemia than symmetrically growth-retarded babies. The diagnosis of SGA and LGA are based on the 10 th and 90 th centile weights for a given sex and gestational age, respectively. A baby with a birth weight below the 10 th centile, but with a length and OFC >10 th centile is considered asymmetrically growth retarded. Serious errors may occur if inappropriate growth standards are applied for a given population. Based on the centiles of this study population, 378 babies were below the 10 th centile of at least one parameter. If the MGRS study centiles are used, 828 babies lie below the 10 th centile of at least one parameter. The additional 450 babies, which need to be followed-up with special attention if the MGRS cut-off values are considered, is an additional burden on the existing low-resource settings. Besides, these babies may in fact not require additional care.
Mother's employment status was not associated with growth parameters at birth. Mother's employment status may have both positive and negative influences on pregnancy. Sleep deprivation, shift work, travelling, physical and mental stress can have a negative effect on foetal growth.  In contrast, employed females are more likely to be better educated, have a higher family income and belong to higher socio-economic stratum.
Birth weight was higher in the second- and higher-order children as compared with the first-born children. It is difficult to explain exactly why the second-order babies had higher growth parameters than the first-born ones. A possible explanation is that a female is more knowledgeable about pregnancy and is probably more aware of the importance of antenatal care and thus more likely to seek antenatal care in the second pregnancy compared with the first one.
In Sri Lanka, it is a common practice, especially in the private sector, to deliver babies electively after completion of 37 weeks of POG, by caesarean section for social reasons. The main reason is the belief in auspicious times. This practice is based on the belief that foetal growth has attained its maximum by 37 weeks of gestation. Our results show that all three growth parameters continue to increase until 41 weeks of gestation. By delivering babies electively after 37 weeks of POG, without a definite indication, deprives the baby of growing to its maximum potential before birth.
Growth parameters at birth increased up to 34 years of maternal age, after which they declined. Teenage pregnancies are considered high-risk; however, there are no reported Sri Lankan studies on the impact of teenage pregnancy on growth parameters at birth. Our results indicate that the mean birth weight and the length of babies born to teenage mothers are significantly lower than that of babies born to mothers ≥20 years of age. After 35 years, all three growth parameters significantly declined, indicating the importance of avoiding pregnancy after 35 years, if possible.
Limitations of the study
Birth weight was not recorded immediately after birth in few babies. Feeding the baby and the passage of meconium and urine may have altered the actual birth weight. However, most babies were weighed within a few hours after birth, and all babies were weighed within 8 h of birth. However, the use of trained personnel to record measurements and the use of standard calibrated equipment for the measurements are strengths of this study.
Conclusions and recommendations
The mean weight, length and OFC at birth of babies in this study population are significantly lower than for babies in the MGRS study. We showed that an additional burden of 450 babies out of 2215 can be misclassified as requiring specialized care if MGRS data are used. This would increase the burden on the already low-resourced health system. In addition, trying to improve the nutritional state of normal babies misclassified as poorly nourished may in fact be detrimental, as the risk of metabolic syndrome is higher when children are overfed to achieve a higher growth centile than their genetic potential. In addition, a significant number of overweight children will be missed by using the findings of the MGRS, as we may be pushing our children to the point of being overweight by using the growth charts provided by the MGRS. Therefore, it would be better if Sri Lanka has its own growth charts so as to carry out meaningful growth monitoring. Birth order, family income, POG and maternal education had significant effects on growth parameters at birth. Maternal age less than 20 years or more than 35 years had a significant negative effect, especially on birth weight.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]
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