Low birth weight in Indian infants compromise their health in later life

Low birth weight, referring to babies that weigh less than 2,500 grams at birth (2.5 kilograms), is an important public health problem in resource-poor countries. The World Health Organization estimates that “15 percent to 20 percent of all births worldwide are low birth weight, representing more than 20 million births a year.”

A news study explains that low birth weight infants “have a higher mortality risk in their first month of life while those who survive infancy face worse health, human capital, IQ, and labor market outcomes. An estimated 18 percent of Indian infants are LBW.”

Researchers from Center for Disease Dynamics, Economics & Policy Inc. (CDDEP), Sam Houston University, and International Institute for Population Sciences (IIPS) made use of instrumental variable regression models with longitudinal data from the Indian Young Lives (YL) survey in Andhra Pradesh, “to estimate the effect of birth weight on cognitive development during childhood in India.

Andhra Pradesh is one of the largest states in India with a population of 52.4 million.

According to Young Lives India, the country has a population of more than 1.25 billion people. It is a country of huge inequalities, with the second-largest number of billionaires in the world but also 25 percent of the world’s poor.” The website also quotes the World Bank, noting that “30 percent of the population, 224 million people, live on less than 1.9 dollars per day.”

The study will be published in Economic Papers: A journal of applied economics and policy.

The press release notes that there is plenty of research on the effects of low birth weight on outcomes in adulthood, but there is “limited evidence linking LBW with mid-childhood outcomes through which the adult outcomes manifest.”

The authors note that “Compared to adult outcomes, mid-childhood outcomes are more policy-relevant because the birth  weight effects on adult outcomes manifest through the mid-childhood years and adult outcomes take many years to appear and therefore are less amenable to policy interventions.”

According to the authors, this is the first study they know of that estimates the effects of birth weight on cognitive outcomes in the mid-childhood years (five to eight years) of children in India.

The Peabody Picture Vocabulary Test, revised edition (PPVT-R) "measures an individual's receptive (hearing) vocabulary for Standard American English and provides, at the same time, a quick estimate of verbal ability or scholastic aptitude," The authors of the study estimate the causal  effect of birth weight on children’s Peabody Vocabulary Test (PPVT) Score, “a measure of cognitive ability and they examine the heterogeneity in the effects of birth weight by socioeconomic characteristics of participants’ households.”

The authors add that “mothers are less likely to be educated compared to fathers, as the primary school completion rate among mothers is 58% while it is 66% among fathers. Households are predominantly rural (58%) and practice the Hindu religion (84%). About 25% of the children belong to socially disadvantaged communities (scheduled social group/scheduled tribe) and 53% of them belong to the top wealth group.”

The study’s findings can be summed up as:

• LBW infants experienced lower test scores compared with normal birth weight infants. 
• A 10 percent increase in birth weight increases cognitive test scores by 0.11 standard deviations at ages 5-8 years. 
• The positive effect of birth weight on a cognitive test score is larger for girls, children from rural households, and those with less-educated mothers. 
• Health policy must be designed to improve neonatal outcomes in India and other LMICs, with policies and initiatives that promote access to prenatal care and maternal nutrition to reduce the risk of LBW.  

“India has the largest birth cohort in the world.  The 26 million children born each year represent a significant opportunity for economic growth,” says study co-author, Dr. Ramanan Laxminarayan, Director, CDDEP.

“However, poor nourishment of mothers results in low birth weight infants, and is likely to result in large numbers of children who are disadvantaged from the outset. This study should be a warning call to improve maternal nutrition.”