A major new study has revealed how often babies are born larger than expected for their age in 23 low- and middle-income countries (LMICs) over the last two decades. The research focused on two conditions — large-for-gestational age (LGA) and macrosomia, both referring to babies who are unusually big at birth.

Why this matters for mothers and babies

The size of a baby at birth can influence its health and the mother’s wellbeing, both immediately and later in life. Larger-than-average babies are more likely to face delivery complications, breathing problems and long-term health risks such as obesity and diabetes. Mothers are also at higher risk of difficult labour and caesarean delivery.

This study, whose results were published in the International Journal of Obstetrics and Gynaecology on November 10, 2025, helps countries understand the scale of the problem — and plan health services that prevent and manage risks related to big babies.

What the study found

• After looking at nearly half a million babies, they found that about 5 out of every 100 babies were bigger than expected for their age during pregnancy. This is what experts call LGA (Large-for-Gestational Age).
• They also looked at more than 300,000 babies and found that about 1 out of every 100 babies weighed 4 kg or more at birth. This is called macrosomia.
• When comparing different parts of the world, Latin America and the Caribbean had the highest number of big babies, while South Asia had the lowest.
• Over the last 20 years (2000–2021), the number of big babies has slowly increased. However, the number of more than normal weight babies has stayed almost the same over time.

A closer look: How the study was done

This was an individual participant data analysis, meaning researchers did not rely on summaries — they analysed raw individual birth records from multiple studies. Data came from subnational, population-based cohort studies across 23 LMICs, spanning more than 20 years.

To ensure a high-quality dataset, researchers only included studies with reliable measurements of birthweight and gestational age, excluding poorly recorded data or very small study samples.

The work was carried out by the Subnational Collaborative Group for Vulnerable Newborn Prevalence, representing scientists from multiple international institutions.

Spotlight on Ifakara

Among the contributors, the study proudly features Dr. Honorati Masanja of the Ifakara Health Institute — reinforcing Tanzania’s global role in advancing maternal and newborn health research.
Dr. Masanja worked alongside partners from institutions including:

• Université Libre de Bruxelles (ULB), Belgium
• Johns Hopkins Bloomberg School of Public Health, USA
• And dozens of research centres across Africa, Asia and Latin America

The lead/corresponding author is Fati Kirakoya-Samadoulougou, based at ULB Brussels and Johns Hopkins. This collaboration demonstrates the growing power of South–South and global scientific partnerships — where LMIC researchers add direct, contextual expertise to global health evidence.

What the findings mean going forward

Although the prevalence of large babies in LMICs is still lower than in high-income countries, the gradual increase in large-for-gestational-age births signals a need to monitor maternal health trends more closely — including nutrition, diabetes and access to antenatal care.

The researchers recommend that policymakers and frontline health programmes:

• Strengthen routine birthweight and gestational age tracking.
• Improve early detection of maternal risk factors.
• Promote healthy maternal nutrition and pregnancy monitoring.

Final takeaway

This landmark study covers nearly half a million births and sheds new light on the silent burden of oversized babies in LMICs — a topic that has received far less attention than low birthweight. It highlights not only the need to protect newborns at risk of being too small, but also those at risk of being too big.

 Read the full research article, here.