New Study Reassesses Long-Term Health of Preterm Adults

Recent research led by the Liggins Institute in Auckland offers new insights into the long-term health outcomes of adults born preterm, challenging some previous assumptions about the consequences of preterm birth. The study, published in Pediatrics, followed individuals who had been part of a double-blind, placebo-controlled trial of antenatal betamethasone, a corticosteroid given to mothers to improve fetal lung development when preterm birth is anticipated. This trial was conducted at the National Women’s Hospital in Auckland, and the follow-up research aimed to assess whether adults born preterm exhibit an increased risk for cardiovascular disorders, diabetes, and other chronic health conditions in midlife.

Preterm birth, defined as delivery before 37 weeks of gestation, affects an estimated one in 10 births worldwide. Historically, preterm birth has been associated with elevated risks for a range of health issues, including hypertension, stroke, diabetes, and other cardiovascular diseases. However, much of the previous research on these long-term outcomes was based on data from individuals born preterm decades ago, before the significant advancements in neonatal care that have occurred in recent years. The contemporary era of improved survival rates for preterm infants, thanks to better neonatal care, prompted the researchers to examine whether these improvements might have mitigated some of the health risks previously associated with preterm birth.

In the study, participants who had been born preterm and who had survived to adulthood were compared with a group of adults born at full term (after 37 weeks of gestation). The researchers focused on a number of health metrics, including diabetes, prediabetes, hypertension, dyslipidemia (abnormal levels of lipids in the blood), and major adverse cardiovascular events such as heart attacks and strokes. They also looked at secondary outcomes, including respiratory function, mental health, educational attainment, and kidney disease.

One of the most striking findings was that, while preterm-born adults had a significantly higher likelihood of developing high blood pressure (34.7% of preterm-born adults compared with 19.8% of term-born adults), the overall incidence of major adverse cardiovascular events was lower in the preterm group. Only 2.8% of those born preterm experienced major cardiovascular events, compared with 6.9% of those born at term. This suggests that although preterm-born adults may face an increased risk of hypertension, this does not necessarily translate into a higher risk of severe cardiovascular events later in life.

When examining other conditions, the study found no statistically significant differences between the two groups in rates of diabetes, prediabetes, or treated dyslipidemia. These results suggest that, in terms of metabolic health, the long-term outcomes for preterm-born adults may not be as dire as previously thought. This is an important finding, as earlier research had raised concerns that preterm birth could predispose individuals to higher rates of metabolic diseases, including diabetes.

Interestingly, respiratory outcomes were generally comparable between the two groups, with no significant differences in the prevalence of chronic respiratory conditions. This contrasts with earlier studies that suggested that individuals born preterm might be at a heightened risk for respiratory issues later in life. The study also found no significant differences in the prevalence of chronic kidney disease between the two groups.

Mental health outcomes were another area of interest in the study. Preterm-born adults reported fewer mental health disorders compared with their term-born counterparts. Specifically, 38.2% of preterm-born adults had a diagnosed mental health disorder, compared with 52.9% of term-born adults. The rate of self-reported depression was also lower in the preterm group, which is an encouraging finding. Previous studies have suggested that individuals born preterm may be at greater risk for mental health issues, particularly anxiety and depression, but the results from this study challenge that assumption, showing that the mental health outcomes of preterm-born adults may not be as severe as previously feared.

In terms of educational attainment and mortality, the study found no significant differences between the two groups. This is an important finding, as preterm birth has previously been associated with delays in cognitive development and lower educational achievement. However, in this cohort, the rates of educational attainment were similar, and there was no significant difference in mortality after the first year of life, which suggests that the survival rates of preterm infants today are high, and their long-term educational outcomes may not be as negatively impacted as earlier generations.

The findings of this study provide a more nuanced view of the long-term health impacts of preterm birth, particularly in the era of modern neonatal care and antenatal corticosteroid use. While preterm birth remains a risk factor for some health conditions, such as high blood pressure, the overall risk of major cardiovascular events appears to be lower than previously expected. Moreover, the lack of significant differences in rates of diabetes, dyslipidemia, and respiratory issues between preterm and term-born adults suggests that the long-term health consequences of preterm birth may not be as dire as once thought, particularly for those born at moderate preterm gestational ages.

This research is significant because it provides a contemporary perspective on the long-term health outcomes of preterm birth, which has been lacking in much of the previous literature. As neonatal care continues to improve, it is important to evaluate how these advancements affect the health trajectories of preterm infants as they reach adulthood. The results of this study highlight the importance of continued follow-up care for individuals born preterm, particularly in monitoring and managing high blood pressure. However, it also suggests that, for many individuals born preterm, the long-term health risks may be less severe than previously assumed.

Reference: Anthony G. B. Walters et al, Health Outcomes 50 Years After Preterm Birth in Participants of a Trial of Antenatal Betamethasone, Pediatrics (2024). DOI: 10.1542/peds.2024-066929