When babies are born in Indonesia, they are immediately put on scales.
Their birth weights are recorded before anything else, before their names, their birth certificates, or even their parents’ first touch.
It all seems ordinary on paper, a few kilograms with one decimal place. The truth is that birth weight is one of the early signs of a baby’s health, affecting the baby's chances of survival, growth, and development.
Babies born with low birth weight (LBW) can carry a heavy burden, especially those in low- and middle-income countries.
My PhD research investigates LBW babies in Indonesia, infants who weigh less than 2.5kg at birth. Indonesia is a vast archipelagic country where more than 280 million people live across numerous islands, each with distinct health practices, traditions, and resources.
With the scale of this country, maternal health care must extend beyond hospitals. It must touch women across islands, languages, and cultures, way before they deliver their babies.
Given this context, birth weight may be the quiet imprint of the life that shaped them long before they were born.
Although this study is set in Indonesia, the message speaks to New Zealand too: LBW may reflect inequities in socioeconomic status, maternal health, and healthcare access.
One question lingers in my mind: what circumstances surround the mother that could increase her baby’s chance of being born with LBW?
To understand this, I used data from the Indonesia Family Life Survey, a 21-year survey that follows Indonesian families and collects records on their health, socioeconomic, and living conditions.
More than 6000 mother-child pairs were analysed, considering not only medical factors but also their social conditions surrounding pregnancy. As expected, babies born prematurely were more likely to be LBW.
Underweight mothers were also more likely to have LBW babies. After all, pregnancy is a delicate journey, shaped by nutrition and the timing of birth.
But LBW is not solely a medical issue. It is also a social one.
This research shows that LBW was associated with mothers’ education, ethnicity, marital status, height, body mass index, as well as infant sex and gestational age.
This suggests that birth weight may be shaped not only during pregnancy but also by the mother’s life before pregnancy, including her access to education, nutrition, culture, and social and economic support.
Lower maternal education, for example, was associated with LBW. Education does not directly change the baby’s weight.
Instead, it may shape many parts of a woman’s life long before she feels the kick in her belly: how she understands the health information she receives, the health care she seeks, the decisions she is able to make, the danger signs in pregnancy she can recognise, and the resources she is able to use during pregnancy.
We also found that short maternal stature was associated with LBW.
Height is not just a biological trait. It may represent the mother’s nutritional status, infections, and environmental conditions throughout her life. In essence, a pregnant woman’s body may carry her own childhood history.
Thus, LBW babies may reveal something beyond the months of pregnancy, but also the years of inequity that the mother endured before pregnancy.
The finding on ethnicity revealed another layer of the story.
Some ethnic groups had higher odds of LBW. Ethnicity was not a direct cause of LBW. Instead, it has a contextual interpretation.
Given the nature of the archipelagic nation, ethnicity is often linked to geographical conditions that shape various health practices, food taboos, cultures, languages, health-seeking behaviour, and healthcare infrastructure.
Seen this way, disparities in LBW incidence may reflect regional and systemic inequities that need to be understood as a whole, rather than judged on individuals or communities.
This is why the study matters. Since LBW is not merely a problem of individual mothers, the solutions need to be broad.
As a physician, I have seen how LBW babies are often examined and discussed at hospitals, with some requiring intensive care in the NICU.
Now, as a researcher, I am learning to look further and dig deeper. By the time a newborn is weighed, the number speaks more than just the baby's weight. It may give us a hint of the interaction among family support, education, nutrition, broader social conditions, and health care systems.
A baby’s birth weight is more than just a number. If we look more closely, it could point to where support may be needed earlier: improving women’s access to education, ensuring adequate nutrition from an early age, and making prenatal care easily accessible.
Mothers’ surroundings matter, from familial support to the surrounding society. Every baby deserves a good start in life, and every mother deserves the conditions to provide it.
Sometimes, we must look beyond the number on the scale and pay attention to the heavier story behind it.
- Farah Nisa is a doctorate student at the University of Otago. This piece was the winner of the 2026 Otago Medical School Research Society Science Writing Prize; as part of the prize the Otago Daily Times publishes the winning entry.