Catch-up Growth of Low Birth Weight Infants: A Study Among the Infants Born in the Backward Areas of Howrah

Background: Babies having low birth weight are comparatively more susceptible to infection and are unable to grow to their full potential of physical and mental development. This often lead to high infant morbidity and mortality. Hence, it becomes important to identify the low birth weight infants and offer them adequate care. This study was carried in the District of Howrah. This study was conductedmong 732 LBW survivors and 314 NBW controls from birth to nine months of age. Their growth trends (weight, length, head and chest circumferences) were followed and compared. Objectives: The physical growth pattern of low birth weight and normal birth weight babies under study were compared, relative influence of certain variables on the catch up growth of LBW infants were to be determined and the catch up growth in terms of increments in Height, Length, Weight, Head and Chest Circumferences were analyzed. Results: The catch-up growth among the LBW infants in almost all the anthropometric measurements were of lower values as compared to their NBW counterparts. However the increments in growth were seen to be higher in different months of age for different measurements. The catch-up growth was contributed by gestational age, birth weight, birth length, birth head and chest circumferences. Regarding catch-up growth, length, head circumference and chest circumference were the parameters to start up early as in the 1 st month in case of chest circumference followed by length and head circumference in the 2 nd month of age. Weight was quite late as much as 4 th month. LBW babies were much closer to their NBW counterparts in the 6 th month in all the parameters under this study.


Introduction
In India, low birth weight has been of a high incidence and the subsequent morbidity and mortality continues to be of a major issue in the domain of public health intervention. The determinants of the growth and development of the low birth weight infants are mostly socio-economic, and the effects of the birth weight are reflected in the growth and development of the infants [4,24]. Majority of the LBW infants show accelerated growth, or catch up growth as it is termed. Most of this catch up growth takes place during 6 to 12 months of life both in terms of weight and/or length, [20,25]. The effect of "Catch-up-growth" is most pronouncedly seen in the LBW infants who tend to catch up mostly in weight during the post-natal period [19,23]. Infants born for small for their gestational age (SGA) show catch up growth in the first few months of their life [14]. India has one-third of all babies born as low birth weight. There have been initiatives adapted by the Indian Government to promote rapid growth in infancy [21]. Infectious morbidities, under nutrition and stunting in children are the key factors that the policy makers have to deal with. However, socio-economic transition and urbanization make the Indian environment uncertain for attaining the optimal growth pattern of such infants. Studies have shown the effect of catch up growth is more pronounced in LBW infants [26]. As we consider catch up growth to be a measure of favorable outcome, it becomes important to identify its determinants [3].
The present study analyses catch up growth and its determinants in a group of LBW infants followed up longitudinally from birth to 9 months of age.
Aims and Objectives: a. To compare the physical growth pattern of low birth weight and normal birth weight babies under study. b. To find out the relative influence of certain variables on the catch up growth of LBW infants.
c. To analyze the catch up growth in terms of increments in Height, Length, Weight, Head Circumference and Chest Circumference.

Materials and Methods
A total of 732 infants born weighing 1500gms or less, in the Howrah District Hospital were considered for this study. On the other hand, 314 infants born of normal birth weight were considered for comparison. The infants were considered from the very first month of their birth in between two weeks to 30 days age. The mother and the family was adequately explained on the scientific base of the study and that the utility of the results derived will further give us knowledge on how to care for the low birth weight infants born and to reduce the number of problems that the families go through.
The following information wererecorded from the Hospital: 1. Birth weight 2. Sex 3. Gestational age assessment 4. Neonatal illness if any 5. Type of milk provided in the very first month. The weight was measured by standard electronic scales while length and circumferential measurements were measured by flexible measuring tapes. The catch-up in all anthropometric measurements was observed. Analysis of Table 1: As weight of the LBW and NBW infants were recorded from birth to nine months of age, it was seen that the mean birth weight of the LBW infants were lower as compared to their NBW counterparts all throughout the period of follow up. The mean increments of weight recorded in each month reveal that in the 4 th , 5 th 6 th and 8 th months the LBW infants showed higher weight increments than the NBW infants. The differences shown in these months were significant at 5% level. Analysis of Table 2: The pattern of weight increment of the preterm and IUGR infants were compared in this table. The observation was that the preterm babies were lower in mean weightas compared to the IUGR infants till the age of 3 months only. Fourth month onwards the mean increment in weight was higher in the preterm babies than their IUGR counterparts. Significant differences at 5%level was seen in the 3 rd , 4 th , 7 th and 8 th month of age. Analysis of Table 3: This table shows the comparison of the increment of length in the LBW and NBW infants from birth to nine months of age. In contrast to weight increments length did not show higher values for the LBW infants all throughout the nine months of age. However 2 nd , 3 rd and 7 th months show significant differences in weight increment at 5% level. Analysis of Table 4: This table compares the length increment among the preterm and IUGR infants from birth to nine months of age. It reveals that the mean length values in the preterm infants were lower all throughout and in contradiction to it the increments showed higher values in all the months of age, and moreover 5 th and 6 th show significant differences at 5% level. Analysis of Table 5: Head circumference measurements were compared here between the LBW and NBW infants through the nine months of age of the infants. Results show the same trend as in case of weight and length measurements that, the LBW infants had lower values in all the months of study while increments had higher values in the 2 nd , 4 th and 6 th month of age as compared to the NBW infants and the differences were significant at 5% level. Analysis of Table 6: Among the LBW infants, the preterm and the IUGR infants were further compared in the measurements of the Head circumference measurements. The IUGR infants caught up at a higher rate as compared to their preterm counterparts. However the preterm infants showed higher increments from the 3 rd month of age and continued till the 9 th month. Signinificant difference at 5% level was found only in the 7 th month. Analysis of Table 7: This table show the measurements of Chest circumference and its comparison in the LBW and NBW infants. The LBW infants here too follow the same trend of having lower values all throughout the nine months of age as compared to the NBW infants. Higher increments were seen in the 1 st to 6 th month of age among the LBW infants. The differences in these month of age show significance at 5% level. Analysis of Table 8: Chest circumference measurements were here compared between the preterm and IUGR infants. The preterm infants here lagged behind their IUGR counterparts almost in measurements as well as increments except in the 8 th month. Significant difference was seen in the 3 rd and 7 th month at 5%level.  Analysis of Table 10: According to this table, the maximum number of LBW infants (608) caught up with their NBW counterparts at the 4 th month (83.0%) after which their proportion gradually decreased till 6 th month of age (81.0%).

Discussion
Low birth weight is one of the major concerns in the domain of public health problems in India and developing countries. The occurrence of LBW in any community is indicator enough of its poor health status of pregnant women and inadequate prenatal care [16]. The babies born low in birth weight have a bad start in life and prove to develop diseases due to recurrent infections, malnutrition and are often handicaps in neuro-developmental stages [8]. Studies show emerging issues of life style diseases like, diabetes, hypertension and coronary artery disease in adult life of the LBW born [15]. Thus, LBW is a risk factor for adverse outcome in life.
In the present study, there was a scope to analyze the growth pattern of the preterm and IUGR infants. The results reveal that in general the preterm infants experienced faster rates in terms of growth increment compared to the IUGR infants. As comparisons were made in context of the growth pattern, between the preterm and IUGR infants, it was observed that the parameters considered here, weight (Table  2), length (Table 4), Head circumference (Table 6) and chest circumference (Table 8), show lower values in all the parameters for the preterm infants than the IUGR infants. This trend persisted all throughout the study period from birth to nine months of age. This observation is well in accordance with various studies like [7,11,15]. However, studies [9,19,22]. differ in saying that the mean weight of the preterm had higher values from the fourth month onwards as compared to the IUGR infants. In the present study, the values for weight also followed the same trend as other measurements. Preterm infants were having lower values as compare to their IUGR counterparts all throughout (Table 2). Considering the monthly increments of the anthropometric measurements, the results reveal in favor of the preterm. This study (according to Table 13) reveals that, the mean Infants Born in the Backward Areas of Howrah weight increment of the preterm was higher as compared to the IUGR infants except for 1 st month and 3 rd month ( Table  2). The mean length increments (Table 4) were higher among the preterm infants consistently throughout the eight months of age, except for the ninth month showing slight lower values. The 5 th and 6 th month differences were found to be significantly higher. Table 6 reveals the differences of increments in HC, where preterm however show higher increments in the 3 rd , 5 th , 6 th , 7 th , 8 th and 9 th months. In case of increments in Chest circumference (Table 8), higher values were in favor of the preterm from the 1 st month till the ninth month except for the 4 th month. When given adequate care, LBW infants can show significant catch -up growth. The monthly incremental variability of the anthropometric parameters is influenced mainly by gestational age, birth weight, effect of illness, nutritional intake, heredity and environmental factors at home [12]. Here the growth of the Normal birth weight (NBW) infants was taken considering it as the standard at each month in order to compare the LBW infants. It was taken into consideration that, both the groups lived in more or less homogenous environmental condition. As all the infants were followed up till nine months of age, analysis of catch-up growth was done up to nine months. In this study, Tables 1,3,5,7 show the comparisons of anthropometric parameters and their increment, between LBW and NBW infants. Table 9 summarize the findings regarding the catchup growth of the LBW under study. According to this, length showed the highest percentage, 85.3 % catch up in the 3 rd month in LBW infants, followed by weight74.6% in the 6 th month. Head circumference showed an increase in the 5 th month among 68.1% LBW infants while 63.6% infants showed catch-up in the chest circumference in the 4 th month age. Absolute values were assigned to the continuous variables for multifactorial analysis.  According to table 16, the binary logistic regression explain 48.4% (R square) of the total variation of catch -up growth, was due to the factors like gestational age, birth weight, length, Head circumference and Chest circumference among the other variables. Birth weight play a statistically significant role in this regression analysis. Thus in prediction of catch -up growth, gestational age, length, Head circumference, and Chest circumference play statistically significant roles.
Binary logistic regression analyses (Tables 14, 15, 16) was performed. It was found that the independent variables like-gestational age, weight, length, Head circumference and Chest circumference had statistically significant correlation with the dependent variable catch-up growth. Whereas, religion, income, maternal literacy and morbidity had no correlations at all. Independent variables were significantly correlated among themselves.

Conclusion
Low birth weight in itself is a concern for all. Babies born LBW are more susceptible to infection and do not grow to their full potential of physical and mental abilities. Hence, it becomes vital to identify the new borns with LBW and provide them adequate care for their survival and well being. As the LBW and the NBW infants lived in more or less homogenous environmental conditions, it can be concluded that, the environmental factors affecting the growth pattern of both the groups were similar. Nearly 24.7% of the infants born in the studied area were LBW infants, which emphasizes the need for implementing new interventions aiming to prevent the birth of low birth weight babies. Despite the existence of good quality antenatal care services catered by the Howrah District Hospital, quite a high incidence (24.7%) of LBW suggests that there is a lacuna in the process. The community level awareness has to be generated so that mothers avail early and adequate ANC. The need for maternal care should also be given more attention.