The New Zealand Very Low Birthweight (VLBW) Study has followed the health and progress of all babies weighing less than 1500 grams when they were born in 1986, and compared them with a cohort of same-aged peers over the past three decades.
Study leader and University of Otago paediatrics emeritus professor Brian Darlow said although there were few significant effects on long-term health for most of the VLBW babies, several challenges remained.
Data last collected from 250 of the VLBW babies between 2013 and 2016, when they were about 28 years old, showed most were thriving in their third decade of life, he said.
"Despite their more challenging start in life, when last tested, the majority of VLBW adults were generally living healthy productive lives, similar to babies born at the same time and at a healthy weight, with the cohort’s mean values for nearly everything we measure within the normal range for age."
However, Prof Darlow said the results also concluded that compared with their term-born peers, VLBW adults at age 28 had higher systolic blood pressure, slightly smaller, stiffer hearts and more visual impairment.
They also experienced slightly poorer lung function and tended to exercise less often and less vigorously than controls.
Extensive testing also showed there was a gap of 9.4 points in adjusted mean IQ between VLBW adults and controls, and some differences in tertiary education levels, employment, welfare dependence and self-perceived executive functioning.
They had also experienced more mental health problems than term-born controls — although this difference was small, he said.
The study suggested VLBW adults, on average, had a more advanced "physiological age" towards the end of their third decade than term-born controls.
"Very preterm birth is a lifetime condition and extra medical surveillance is warranted, particularly for blood pressure, heart, lung and kidney function as well as blood sugar control."
The VLBW Study is now applying for funding for further testing of the cohort, now aged about 40.
The study will be taken over by University of Otago senior lecturer and paediatrician Dr Sarah Harris, who said it was vitally important the study be continued.
The aim was to test if subsequent physiological ageing of the very low birthweight cohort would accelerate, or remain at the same pace as others.
"We have a unique opportunity to study this and build on the tremendous contribution by study participants to our understanding of the long-term impact of premature birth on health and wellbeing.
"We know that accelerated ageing brings with it the risk of earlier chronic disease, with a suggestion also that babies born very premature may develop hypertension, heart disease and lung problems earlier.
"These factors make it vitally important we complete further assessment as they age."
