Study Background and Disease Burden
Antenatal corticosteroids, primarily betamethasone, are routinely administered to pregnant individuals at risk for preterm birth, aiming to mitigate neonatal morbidity, notably respiratory distress syndrome. Despite this clinical benefit, there has been growing concern regarding the potential long-term adverse effects of these medications on subsequent generations. Previous animal studies have identified endocrine and metabolic disruptions in both the first (F1) and second generations (F2) following in utero exposure to corticosteroids. These findings highlight the necessity for human studies to evaluate the safety and long-term health implications of antenatal corticosteroid exposure in humans.
The Auckland Steroid Trial (AST), conducted in the late 1970s and early 1980s, initially sought to examine the safety and efficacy of antenatal betamethasone in preventing respiratory complications in premature infants. However, the unexpected potential for transgenerational effects prompted further examination into the health outcomes of the F2 generation, primarily those whose mothers were randomized to receive either betamethasone or placebo.
Study Design
The follow-up study, conducted by Lord et al., involved participants of the original AST, which included pregnant women (F0) expected to deliver between 24 to 36 weeks’ gestation, who were randomized to receive either betamethasone or placebo. Upon reaching 50 years of age, the first generation (F1) participants and their offspring (F2) were assessed using self-report questionnaires linked with health data.
Key features of the study included:
– **Population**: Women enrolled in the AST-derived cohort, with their F1 offspring now reaching 50 years of age; 213 F2 participants were eventually recruited.
– **Interventions and Comparators**: Comparison of outcomes between the parental exposure groups of betamethasone vs. placebo.
– **Outcomes**: The primary outcome was the body mass index (BMI) z-score for the F2 generation. Secondary outcomes encompassed various health domains, including respiratory health, cardiovascular risk factors, neurodevelopmental outcomes, mental health, and general well-being.
Key Findings
The follow-up study analyzed health data for 213 F2 participants, with 144 having complete BMI records. Notably, there was no discernible difference in BMI z-scores between the offspring of parents exposed to betamethasone and those whose parents received placebo: 0.63 (SD 1.45), N = 77 versus 0.41 (SD 1.28), N = 67, yielding an adjusted mean difference of 0.16 (95% CI: -0.37 to 0.69).
Furthermore, no significant differences were observed in the rates of overweight or obesity, diabetes, respiratory disease, cardiometabolic risk factors, neurodevelopmental impairments, mental health challenges, or adverse social outcomes when comparing parental betamethasone exposures versus placebo. Despite the reassuring nature of these findings, it is important to note that confidence intervals for some of these outcomes were broad, suggesting a potential for undetected differences.
Expert Commentary
The findings of the Auckland Steroid Trial have profound implications for current clinical practices involving the use of antenatal corticosteroids. As healthcare providers continue to support preterm labor management, the data emanating from this long-term follow-up instills a degree of confidence in the understanding that the intergenerational safety profile of antenatal corticosteroids appears generally favorable.
However, experts note the necessity for cautious interpretation due to several factors, including the small sample size of the follow-up group compared to the original trial cohort and the potential variances in healthcare contexts over the decades since the original study. It highlights the importance of continued surveillance and research into the long-term effects of antenatal treatments on future generations, especially in light of evolving healthcare practices and environmental factors.
Conclusion
The 50-year follow-up of the Auckland Steroid Trial provides critical data indicating that antenatal corticosteroid exposure in the F0 generation does not significantly correlate with adverse health outcomes in the F2 generation. Given the ongoing need for safe management of preterm birth, these findings should provide clinicians and policymakers with reassurance regarding the long-term safety of antenatal corticosteroids. Nonetheless, further research is warranted to strengthen the evidence base, elucidating any subtle intergenerational effects that may arise. Continued public discourse and future investigations will be crucial, as they contribute to refining clinical guidelines and optimizing maternal-fetal health outcomes.
References
Lord LG, Walters AGB, Crowther CA, Dalziel SR, Eagleton CL, Gamble GD, Harding JE, McKinlay CJD, Milne BJ, May RW. Second generation effects of antenatal corticosteroid exposure: 50-year follow-up of the Auckland Steroid Trial. J Dev Orig Health Dis. 2025 Aug 1;16:e25. doi: 10.1017/S204017442510007X. PMID: 40747737.