Why a Baby Born Too Soon Has Very Different Odds Depending on Where It Is Born

What a large global study (Getaneh et al., BMC Pediatrics 2025) of nearly one million very premature babies tells families about survival, and why the numbers are not the same everywhere

When a baby is born before 29 weeks of pregnancy—more than eleven weeks early—its chance of surviving depends enormously on where it is born. A major new study that combined data on nearly one million such babies from 44 countries found that about 61 out of every 100 survived to go home overall, but that this rose to roughly 69 out of 100 in wealthy countries and fell to about a third in the poorest ones [1]. In other words, the single biggest thing separating a baby who lives from one who does not is often not the baby—it is the hospital, the country, and the resources around it.

What "extremely premature" means, and why it is so serious

A full-term pregnancy lasts about 40 weeks. Babies born before 29 weeks are among the most fragile patients in all of medicine: their lungs, brains, guts, and eyes are still forming, and they usually need weeks or months of intensive care simply to do what a womb would have done for them. Prematurity is the single most common reason children die before the age of five, and being born too early sets the stage for many of those deaths [2]. Each year an estimated 13.4 million babies are born prematurely worldwide, a number that has barely changed in thirty years, so this is not a rare problem but a constant one [3].

How families used to face this, and what changed

For much of the history of newborn intensive care, the survival numbers doctors shared with frightened parents came almost entirely from wealthy countries with well-funded hospitals. Over the past few decades, those hospitals learned to save smaller and smaller babies: large record-keeping projects in the United States showed survival climbing year after year, and national studies in France and Sweden showed that with early, active treatment, even babies born at 22 to 24 weeks could sometimes survive [4], [5], [6]. But researchers also discovered something important: two hospitals could take in the same kinds of babies and get very different results, mostly because of differences in how aggressively they chose to treat the tiniest infants [7]. The uncomfortable truth hidden inside those success stories was that most of the world's premature babies are not born in those well-resourced hospitals at all—and the numbers everyone quoted rarely reflected the places where prematurity is most common. This new study was designed to look at the whole world, not just its wealthiest corners.

What the researchers did

The team gathered every credible study they could find—searching eight databases and even general web sources through mid-2024—that reported how many extremely premature babies survived [1]. They deliberately cast a wide net to include research from lower-income regions that big reviews usually miss. In the end they combined 227 studies covering 917,176 babies across 44 countries, then used standard statistical methods to pool the results and, importantly, to compare survival between different income levels, world regions, gestational ages, and time periods. They also rated how trustworthy each study was, so that stronger studies could be weighed appropriately.

The gap between rich and poor settings

The clearest finding was a steady ladder that followed national wealth. Survival was about 69 out of 100 in high-income countries, 56 in upper-middle-income countries, 34 in lower-middle-income countries, and 32 in low-income countries [1]. By region, the highest survival was in East Asia and the Pacific and in North America (around 72–73 out of 100), and the lowest was in sub-Saharan Africa (about 31 out of 100). Put plainly: a premature baby in the best-resourced settings was more than twice as likely to survive as an identical baby in the least-resourced ones. This is what researchers mean by "inequity"—not a difference in the babies, but a difference in the care available to them.

Why every week of pregnancy matters so much

The study also confirmed, across the largest collection of data ever assembled on this question, how much each additional week before birth changes the odds. Survival rose from about 28 out of 100 for babies born at 22 weeks, to 42 at 23 weeks, 55 at 24 weeks, 70 at 25 weeks, 80 at 26 weeks, 84 at 27 weeks, and 87 at 28 weeks [1]. Surviving is only part of the picture, though. The study also looked at how many survivors went home without a major complication, and at the earliest births that share was much smaller—only around 14 in 100 at 22 weeks, rising to about 45 in 100 at 25 weeks and 70 in 100 at 28 weeks. This is why doctors talk with families not only about the chance of survival but also about the chance of surviving without serious lasting problems; at the very earliest births, those are two quite different numbers.

A confusing result, explained

One finding looked alarming at first: when all studies were lumped together, survival appeared to drop in the most recent years compared with the early 2000s. But when the researchers focused on the highest-quality studies, that apparent decline disappeared and even reversed [1]. The explanation is subtle but reassuring. In recent years, more hospitals have begun actively treating babies born at 22 and 23 weeks who, in the past, would have been considered too young to save and would not have been counted at all. Adding these extremely fragile babies to the tally naturally pulls the overall survival percentage down, even while care is genuinely getting better. It is a reminder that a survival number means very little unless you know exactly which babies were included in it [7], [8].

What the complications tell us

Among babies who survived, the most common serious complication was a chronic lung condition called bronchopulmonary dysplasia, affecting about 31 in 100 survivors—and it was the only major complication that became more common over time [1]. That increase is, in a strange way, a sign of progress: as more of the very smallest babies survive, more of them live long enough to develop lung problems that require ongoing support. Other serious complications—severe eye disease, severe bleeding in the brain, and severe bowel injury—all became less common over the years. For families, this means a premature baby today is more likely than in the past to come home needing help with breathing, and follow-up care is built around that reality [9].

What this means for families

If your baby is at risk of being born very early, the most useful thing to understand from this research is that survival statistics are not universal facts—they are snapshots of particular places, times, and groups of babies. A number from a large hospital in a wealthy country may be very different from what is realistic in a smaller or lower-resourced unit [10]. The best questions to ask your care team are specific ones: What are the chances for a baby of this exact gestational age, in this specific unit, receiving active treatment? And of the babies who survive, how many go home without major problems? Good clinicians welcome these questions, because being clear about which number applies to your situation is part of honest, compassionate counseling [11]. It can also help to understand why place matters so much. Caring for a baby born before 29 weeks takes a great deal of equipment and expertise — machines to help with breathing, careful control of temperature and nutrition, ways to prevent and treat infection, and staff trained specifically in newborn intensive care. Wealthier hospitals tend to have more of these resources, which is a large part of why their survival numbers are higher. This is also why doctors sometimes recommend, when there is time, moving a mother expected to deliver very early to a hospital with a higher level of newborn care before the birth: getting the baby to the right place in advance can improve its chances [7]. None of this is about blame or about giving up — it is about being clear-eyed so that families and their care teams can make the best possible decisions together for their own baby, in their own circumstances.

What researchers are working on next

The study's authors are clear that the biggest problem is missing information: very few studies came from low-income countries, and none of the poorest settings contributed data on survival without complications [1]. Their main call is for better record-keeping in the parts of the world where most premature babies are actually born, so that future advice rests on real evidence rather than guesses borrowed from wealthier places [12]. Closing that information gap is a first step toward closing the survival gap itself—so that one day, a baby's chances depend far less on the map and far more on the care every family deserves.

References

  1. Getaneh T, Homaira N, Kasaye H, Tapawan SJC, Chughtai AA, Lui K, et al. Global inequities in the survival of extremely preterm infants: a systematic review and meta-analysis. BMC Pediatrics. 2025;25(1):579. doi:10.1186/s12887-025-05933-w ↩
  2. Cao G, Liu J, Liu M. Global, regional, and national incidence and mortality of neonatal preterm birth, 1990–2019. JAMA Pediatrics. 2022;176(8):787–796. doi:10.1001/jamapediatrics.2022.1622 ↩
  3. Ohuma EO, Moller A-B, Bradley E, et al. National, regional, and global estimates of preterm birth in 2020, with trends from 2010: a systematic analysis. Lancet. 2023;402(10409):1261–1271. doi:10.1016/S0140-6736(23)00878-400878-4) ↩
  4. Stoll BJ, Hansen NI, Bell EF, et al. Trends in care practices, morbidity, and mortality of extremely preterm neonates, 1993–2012. JAMA. 2015;314(10):1039–1051. doi:10.1001/jama.2015.10244 ↩
  5. Ancel P-Y, Goffinet F, Kuhn P, et al. Survival and morbidity of preterm children born at 22 through 34 weeks' gestation in France in 2011: results of the EPIPAGE-2 cohort study. JAMA Pediatrics. 2015;169(3):230–238. doi:10.1001/jamapediatrics.2014.3351 ↩
  6. Norman M, Hallberg B, Abrahamsson T, et al. Association between year of birth and 1-year survival among extremely preterm infants in Sweden during 2004–2007 and 2014–2016. JAMA. 2019;321(12):1188–1199. doi:10.1001/jama.2019.2021 ↩
  7. Rysavy MA, Li L, Bell EF, et al. Between-hospital variation in treatment and outcomes in extremely preterm infants. New England Journal of Medicine. 2015;372(19):1801–1811. doi:10.1056/NEJMoa1410689 ↩
  8. Liu L, Oza S, Hogan D, et al. Global, regional, and national causes of child mortality in 2000–13, with projections to inform post-2015 priorities: an updated systematic analysis. Lancet. 2015;385(9966):430–440. doi:10.1016/S0140-6736(14)61698-661698-6) ↩
  9. Myrhaug HT, Brurberg KG, Hov L, Markestad T. Survival and impairment of extremely premature infants: a meta-analysis. Pediatrics. 2019;143(2):e20180933. doi:10.1542/peds.2018-0933 ↩
  10. Ramaswamy VV, Abiramalatha T, Bandyopadhyay T, et al. ELBW and ELGAN outcomes in developing nations: a systematic review and meta-analysis. PLoS One. 2021;16(8):e0255352. doi:10.1371/journal.pone.0255352 ↩
  11. A tale of two cities: global inequities at the limits of neonatal survival. Pediatric Research. 2026. doi:10.1038/s41390-026-04933-5 ↩
  12. Li YX, Hu YL, Huang X, et al. Survival among periviable infants stratified by income level and time period: a systematic review and meta-analysis. Frontiers in Public Health. 2024;12:1454433. doi:10.3389/fpubh.2024.1454433 ↩