Anthropometric measurements of Sri Lankan newborns

A s tudy was conducted with t h e . a i m of establishing the mean birth weight, crown-heel length and head circumference for Sri Lankan newborns. A total of 1325 normal, singleton babies (993 Sinhalese and 332 Moor) with ultrasonically confirmed period of gestation, born at the Maternity Unit of the Base Hospital Kegalle, were selected..Means ancLstandard deviations for the above measurements of the Sinhalese and Moor babies were established. Since the number of babies belonging to the Tamil ethnic group was small for statistical analysis, they were excluded from the study. For all three measurements, the mean values of male newborns were higher than those of the female newborns. When compared with the Sinhalese, the Moor males and females had highly significant higher values for birth weight, crownheel length and head circumference (P<0.001). Simple linear regression analyses were carried out between the baby's weight and maternal measures such as height, weight, age and parity. A significant relationship was observed between the baby's weight and mother's weight.


Introduction
The anthropometric parameters at birth are considered to be of great value when assessing intrauterine growth.Comparison of these birth measurements with established standards provides a reliable and a simple method of identifying the infant that deviates from the normal, and is at risk of early postnatal t morbidity.
There are numerous studies on anthropometric standards at birth from other parts of the world (1, 2, 3, 4, 5, 6).The studies available for the Sri Lankan newborns have been conducted mainly to establish the birth weight (7,8,9,10 & 11) and to find out the factors affecting the birth weight (10,11).The study conducted by Amarasinghe (12) has established the values for the head circumference of males and females at birth, and Ratnayake, Wikramanayake and Godawatte (13) reported values for several anthropometric characteristics of the newborn.
At present, the physical growth of a newborn is evaluated by comparing body measurements such as weight, crown-heel length and head circumference, with standards established in Western countries.These reference standards have a limited international comparative value, as they are obtained from white Caucasian populations.
The present study was undertaken with the aim of establishing norms for birth weight, crownheel length and head circumference of the Sri Lankan newborn.The influence of socio economic status, ethnicity, gestational age, parity, baby's sex, mother's weight and height, on these parameters was also investigated.

A total of 1325 normal, singleton babies, 993
Sinhalese and 332 Moor, born at the Maternity Unit of the Kegalle Base hospital were selected for this study.On an average, there are 6000 deliveries taking place per year at this hospital.
Only those infants whose mother's date of the last menstrual period (LMP) was certain, and the.duration of gestation, calculated from the LMP was consistent.with the one obtained by ultrasound examiantion, were included.Babies Deepthi Nanayakkam of diabetic and hypertensive mothers, and those with clinically evident congenital malformations were excluded from the study.Data regarding the mother's age, occupation, ethnicity, weight, height, parity and the husband's occupation, were obtained from the hospital records, and also by personal interview.
Birth weight, crown-heel length, and head circumference, were measured soon after birth.All babies were weighed on a metric scale which allowed readings to the nearest 100 grams.The scale was periodically checked for zero error.The crown-heel length was measured keeping the baby in the supine position on a measuring board.The head circumference was measured around the largest occipito-frontal circumference using a non-stretchable plastic measuring tape.

The gestational age was calculated to the nearest week, counting from the first day of the last menstrual period (LMP). The socio-economic status of a newborn was identified on the basis of the parents' occupation and the educational level. The newborns included in the study belonged either to the low or middle socio-economic status.
The means and standard deviations were calculated for the male and female Sinhalese and Sri Lankan Moor newborns.As the number of babies belonging to the Tamil ethnic group was small, they were excluded from the study.

Results
Table 1 shows the mean anthropometric values in the two ethnic groups, for males and females separately, and males and females combined.For all three measurements, the mean values of the male newborns are greater than those of the female newborns.Statistically significant differences (P<0.01) are observed between the Moor males and the females with regard to the head circumference and the birth weight, and also between the Sinhalese males and females with regard to the head circumference.
The Moor male and female newborns as compared to the Sinhalese male and females, are heavier, taller and have greater head circumference values.These differences are statistically significant (P<0.001).
Tables 2 and 3 present the mean values of weight, length and head circumference of the Sinhalese and Moor male and female newborns against gestational age.The values for the intrauterine growth in weight, length and head circumference increase as the gestational age increases.

Discussion
The sample studied included infants of socioeconomically similar mothers belonging to two ethnic groups, the Sinhalese and Moor.The two ethnic groups were considered separately when establishing the mean values for birth weight, crown-heel length and head circumference, as the ethnicity or race is known to influence these parameters (2,5).
All anthropometric measurements differed significantly between the two ethnic groups.This is not surprising as race-specific anthropometric measurements have been described in adults (7).
Socio-economically the Moor community was not significantly different from the Sinhalese.However, traditionally the Moor are known to place more emphasis on their health, especially of their women.This leads to more medical consultations, better nutrition and better health care for pregnant mothers.This could lead to the production of healthier babies.The fact that most Moor women are not employed, may lead to their getting the required rest, especially in the afternoon hours.This could have lead to the increase in the birth weight.Most Moor also live amongst extended families, where other members of the family share the burden of house-hold duties, thus relieving the pregnant woman of much toil.Such social, cultural and dietary habits, prevalent in the Moor community, may contribute in some form to the healthier state of the babies born to these mothers.
Numerous studies have shown that male babies are larger than the female babies (6, 9, 10, 13).