Mild low birthweight carries increased childhood hypertension risk

Children born with mild low birthweight (LBW) are at increased risk of hypertension, according to new research.

In a cohort of elementary school students in Japan, those with vs without hypertension were significantly more likely to have been born with LBW (18.3 percent vs 8.3 percent; p=0.011) and have a birthweight of less than the 10th percentile for their gestational age (14.10 percent vs 7.50 percent; p=0.034). [PAS 2025, abstract 4110.3]

Multivariate logistic regression models adjusted for age, gender, and BMI showed that LBW was associated with more than twofold odds of developing hypertension in childhood (adjusted odds ratio [OR], 2.605, 95 percent confidence interval [CI], 1.354–5.014; p=0.004).

The same was true for birthweight of less than the 10th percentile of gestational age, which was associated with increased odds of hypertension (adjusted OR, 2.180, 95 percent CI, 1.026–4.636; p=0.043).

“Most studies reporting an association between LBW and hypertension include very low birth weight infants (<1,500 g). [And] according to the result of this study, even relatively mild low body weight can be a risk factor for the development of hypertension in school-age children,” reported lead investigator Prof Toshiki Masuda from the Shiga University of Medical Science in Otsu, Shiga, Japan.

Masuda noted that the findings reflect the pathologically known association between low body weight and fewer nephrons. [Kidney Int 2000;58:770-773]

“In children with LBW, it might be possible to prevent the development of future cardiovascular disorders by evaluating blood pressure (BP) in elementary school and intervening early in cases of hypertension,” he said.

The study included 1,121 elementary school students, of which 1,050 had hypertension (mean age 7.83 years, 51.4 percent female) and 71 had no hypertension (control; mean age 8.06 years, 43.6 percent female). Children with hypertension were significantly shorter than those without the condition (mean height, 125.5 vs 128.4 cm; p=0.036), but their body weight was similar (mean, 26.0 vs 27.3 kg).

Data on age, gestational age, birth weight, and gender were obtained using questionnaires. Height, weight, and upper arm circumference were measured. Finally, systolic and diastolic BP were measured three times using an electronic device. Based on the 2017 American Academy of Pediatrics BP criteria, hypertension was defined if both the last measured BP and the mean BP met or exceeded the 95th percentile.

Masuda acknowledged several study limitations, including the lack of information about pregnancy complications that could affect birth weight (eg, gestational diabetes mellitus) and the lack of data on height at birth, which made it impossible to establish a diagnosis of small for gestational age. “For this reason, the association with hypertension was evaluated only for birth weights less than the 10th percentile.”

Furthermore, “office BP was measured on only one visit; therefore, it might not correctly define hypertension,” he added.