Beyond birthweight: Unpacking how a mother's background shapes a preterm baby's adult wellbeing

Being born very preterm or with a very low birthweight (we call this VP/VLBW) is a tough start in life. We know it can lead to more health and developmental challenges down the road, stretching right into adulthood. But does this start affect everyone in the same way? Or do some factors, like a mother's age or education, change the long-term picture for these individuals? 

A new study I recently completed with a team of international researchers explores this question and we recently published our findings in Social Science & Medicine https://www.sciencedirect.com/science/article/pii/S0277953625005118 .  

Our work, ‘A Heterogeneity Analysis of Health-related Quality of Life in Adults Born Very Preterm or Very Low Birthweight across the Sociodemographic Spectrum’, uses sophisticated methods to give us a more nuanced understanding of the impact that socioeconomic factors have on those born preterm or with very low birthweight. It’s not just about if there’s an impact, but who feels it most. This is a story about long-term health, about fairness, and about how early life circumstances, even those of a parent, can cast a long shadow. 

 What's the big deal about Quality of Life? 

When we talk about health, it's not just about the absence of disease. Health-Related Quality of Life (HRQoL) is a broader measure that captures how someone feels about their physical, mental, and emotional health, and how it affects their daily life. For adults born VP/VLBW, previous research has already shown, on average, a dip in this quality of life. 

But averages can hide a lot. Are the effects of being born VP/VLBW a flat line, the same for everyone? Or are there differences depending on someone's background? That's what this study set out to uncover.  

Looking deeper: What did the researchers do? 

We took a close look at data from three long-running studies in Europe and Australia (the Bavarian Longitudinal Study, The Victorian Infant Collaborative Study, and the EPICure Study). These studies have followed individuals born VP/VLBW (less than 32 weeks’ gestation or under 1500g) and compared them to peers born at term, tracking their health into early adulthood (ages 18-26). 

To measure HRQoL, we used a detailed questionnaire called the Health Utilities Index Mark 3 (HUI3). Then came the clever part: instead of just looking at average differences, we used advanced statistical methods called Bayesian Causal Forests and Shrinkage Bayesian Causal Forests, which use lots of decision trees to estimate treatment effects while reducing extreme or overconfident results. 

We specifically wanted to see if the impact of being born VP/VLBW on adult HRQoL changed based on maternal age at birth, maternal education level and maternal ethnicity. 

What did we find? The uneven impact 

The findings were striking and highlighted that a mother's background does indeed play a crucial role:  

A mother's age matters: Adults born VP/VLBW to younger mothers (aged 25 or younger at the time of giving birth) experienced the most significant hit to their quality of life in adulthood. Their scores from the detailed questionnaires (the Health Utilities Index Mark 3 scores) were, on average, 0.08 points lower than their term-born peers. To put that in perspective, a change of 0.03 on this scale represents a threshold for clinical importance. This means such a difference is recognized as having a tangible and meaningful effect on patients’ overall health and wellbeing. For those born to mothers aged 26 and older, the negative impact was much smaller or even negligible. 

Education makes a difference: A similar pattern emerged with maternal education. Adults born VP/VLBW whose mothers had a lower level of education saw a notable dip in their Health-Related Quality of Life (HRQoL) scores (around -0.05 points). However, for those whose mothers had a high level of education, being born VP/VLBW had almost no discernible negative impact on their adult quality of life. 

Ethnicity: In this particular study, there wasn't much difference in the HRQoL outcomes based on maternal ethnicity (White vs. Non-White), though we did note there was less variation in ethnicity within the cohorts studied. 

These results clearly show that the long-term consequences of a VP/VLBW birth are not uniform. Socioeconomic factors, proxied here by maternal age and education, appear to significantly modify these outcomes.  

So, what does this mean for us? The ‘why’ and the way forward 

The findings strongly suggest that higher socioeconomic status, reflected by higher maternal education and often associated with older maternal age at first birth, acts as a powerful protective factor for individuals born VP/VLBW. 

Why might this be? The paper suggests several interconnected reasons: 

Resources: Mothers with higher education and often greater financial stability may have better access to resources, including better healthcare during and after pregnancy, better nutrition, and more supportive home environments. 

Health literacy: Higher education can lead to better understanding of health information and greater ability to navigate complex healthcare systems, advocating effectively for their child’s needs. 

Reduced stress: Socioeconomic stability can buffer against chronic stress, which is a known risk factor both for preterm birth and for developmental challenges. 

These insights are critical. They tell us that simply improving neonatal medical care, while vital, might not be enough to level the playing field for all children born preterm. We also need to look at the broader social picture.  

What are the takeaways? 

Targeted support is key: The study highlights that individuals born VP/VLBW to younger mothers and mothers with lower educational attainment are a particularly vulnerable group needing more focused, long-term support. 

Address social determinants: To truly improve long-term outcomes for those born preterm, policies and interventions need to tackle the underlying social and economic factors that shape health. This could include programs that support young mothers, improve educational opportunities for women, and provide economic safety nets for vulnerable families. 

Think distribution, not just averages: When we evaluate health interventions or plan services, we need to consider who benefits most and who might be left behind. Our research champions looking at these ‘heterogeneous effects’.  

What's next? 

As a research team, we acknowledge that our study, while powerful, uses data from individuals born between 1985 and 1995. Neonatal care has advanced since then. Future research will need to explore if these disparities persist in more recent cohorts and across different healthcare systems, including low- and middle-income countries. 

This study provides a compelling reminder that a child's start in life is profoundly shaped by the environment they are born into, including the resources and support available to their mother. By understanding these complex interactions, we can move towards a future where every child, regardless of their birth circumstances or their mother's background, has the best possible chance to thrive.