Reducing maternal smoking during pregnancy could lower hypertension rates in children

Maternal smoking during pregnancy may be associated with higher blood pressure and increased risk of hypertension in children, according to a new ECHO Cohort study led by Lyndsey Shorey-Kendrick, PhD, of Oregon Health & Science University and Christine Ladd-Acosta, PhD, of Johns Hopkins University.

Blood pressure that is higher than normal in childhood, including diagnosed high blood pressure, can increase the risk of developing high blood pressure later in life, a major risk factor for heart disease. Previous studies examining prenatal smoking exposure and childhood blood pressure have produced mixed findings. Many relied on self-reported smoking or focused only on systolic blood pressure, the top number in a blood pressure reading that reflects pressure when the heart beats. Fewer studies examined diastolic blood pressure, the bottom number that reflects pressure when the heart rests between beats.

To address these gaps, researchers used data from the ECHO Cohort to examine how smoking during pregnancy was related to both systolic and diastolic blood pressure in children. The study included 13,120 children born between 1999 and 2020 from 52 ECHO Cohort Study Sites across the United States, including Puerto Rico. Researchers assessed smoking during pregnancy using self-reports, medical records, and urine samples collected during pregnancy, and measured children's blood pressure between ages 3 and 18.

Children whose mothers smoked during pregnancy were more likely to have higher blood pressure and a greater risk of hypertension. The study distinguished between "any reported smoking," which is based on what mothers shared in surveys or medical records, and "active smoking," which is confirmed by a urine test for cotinine, a marker of recent tobacco use. Active smoking during pregnancy was linked to even higher blood pressure in children.

Key takeaways include:

• Self-reported smoking during pregnancy was associated with higher diastolic blood pressure and increased risk of childhood hypertension.
• Associations were stronger among female children and tended to increase with age.
• Active smoking during pregnancy, identified using urine samples, was associated with higher systolic and diastolic blood pressure and greater risk of hypertension.
• Self-reported secondhand smoke exposure during pregnancy was not associated with higher blood pressure in children.

These findings suggest that reducing maternal smoking during pregnancy could lower hypertension rates in children and adults."

Dr. Christine Ladd-Acosta, PhD, Johns Hopkins University

This collaborative research, titled "Association of Maternal Smoking During Pregnancy with Childhood Blood Pressure and Hypertension in the ECHO Cohort," is published in Circulation.