11 April 2012

Extremely preterm toddlers at risk for hypertension

Children born extremely preterm have an increased risk of high blood pressure by the time they're two and half years old, a study shows.


Children born extremely preterm have an increased risk of high blood pressure by the time they're two and half years old, a study from Sweden shows.

"We propose that all very preterm children should have their blood pressure measured regularly throughout childhood to detect and treat hypertension," the researchers wrote in a report online April 2nd in Paediatrics.

That's true for both genders, lead author Dr Anna-Karin Edstedt Bonamy from Karolinska Institutet, Stockholm said. "Early life exposures matter for later health," she added. "High blood pressure in childhood predicts high blood pressure in adulthood."

Preterm kids have higher blood pressure

It was already known that children born preterm have higher than average blood pressure in childhood and in adolescence. For their study in two-year-olds, Dr Bonamy and colleagues analysed data from 68 children in the Extremely Preterm Infants in Sweden Study (EXPRESS) cohort and 65 controls born at term.

The children in EXPRESS were born at <27 weeks of gestation between 2004 and 2007, weighing an average of 810 g.

At age two and a half, the preterm children had significantly higher systolic and diastolic blood pressures than did age-, gender-, and height-matched children born at term, the authors found.

Preterm boys had significantly higher systolic and diastolic pressure z scores compared to male controls, whereas the preterm girls had higher z scores than control girls only for diastolic pressure.
Gender differences in preterm scarce

"The knowledge of gender differences after preterm birth is so far scarce," Bonamy said. "We have previously shown that BP is elevated also in girls born preterm when studied in adolescence, and we could not find any signs of gender difference in another follow-study of a prospectively assembled cohort of adolescents born very preterm."

"Considering that the present study was not powered to investigate gender differences, we still recommend the same type and frequency of monitoring in preterm girls and boys," she added.

There was no association between children's blood pressure and maternal hypertension or antenatal steroid treatment, nor could blood pressure be correlated with any major neonatal morbidity.

Although blood pressure at follow-up did not correlate with foetal or neonatal growth, children with a larger post-neonatal weight gain had lower blood pressures.

Encourage physical activity

The same children will have comprehensive evaluations of the heart and great arteries, lung function, and physical activity at age six, Bonamy said.

"We are also evaluating neurodevelopmental outcome because it is of interest to correlate blood pressure not only to perinatal risk factors and cardiovascular measures, but also to cognition and behavior. Later in childhood/adolescence, we are planning to do 24-hour blood pressure measurements and investigate their physical capacity," she added.

"Primary cardiovascular prevention measures are probably important to improve later health outcomes among subjects born preterm, although follow-up studies of preterm birth into adulthood are still largely lacking," Dr Bonamy said. "Monitor blood pressure, prevent obesity, and encourage physical activity early in life would be my major recommendations!"

(Will Boggs MD, Reuters Health, April 2012) 

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Dr Jacomien de Villiers qualified as a specialist physician at the University of Pretoria in 1995. She worked at various clinics at the Department of Internal Medicine, Steve Biko Hospital, these include General Internal Medicine, Hypertension, Diabetes and Cardiology. She has run a private practice since 2001, as well as a consultant post at the Endocrine Clinic of Steve Biko Hospital.

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