Maternal Obesity Linked to Child Heart Defects

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Compared to women at ideal weight, women who are overweight at the beginning of their pregnancies are at an increased risk for giving birth to a child with certain heart defects, including defects in both the ventricular and atrial chambers of the heart, pulmonary valve stenosis, and septal defects (the septum is the wall that divides the two sides of the heart).

Sonja Rasmussen MD of the CDC’s National Center on Birth Defects and Developmental Disabilities has reported her study findings online in the American Journal of Obstetrics and Gynecology.

The data was gathered from the National Birth Defects Prevention Study that involved over 12,000 infants born between 1997 and 2004, about half of which were born with congenital heart defects. Women who were classified as overweight at the beginning of pregnancy, defined as a BMI of over 25 but less than 35, were found to have a 15% increased risk. However, as weight increased, so do risks. For women classified as obese, BMI over 35, the risk jumped to 30%.

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The most serious of the 10 congenital heart defects related to obesity is hypoplastic left heart syndrome. The left ventricle, the heart’s primary pumping chamber, is underdeveloped. The defect is often fatal in the first few weeks of life without treatment. Surgery is required soon after birth to allow the larger right ventricle to pump the oxygenated blood throughout the body. Some infants require a heart transplant. HLHS occurs in about 4 of every 10,000 live births.

Mothers of infants with heart defects were found to have two primary risk factors related to weight: gestational diabetes and hypertension during pregnancy.

Diabetes has previously been linked to birth defects. However, because the heart forms early in the pregnancy (between 14 to 60 days after conception) and gestational diabetes occurs later, researchers were suspicious of the findings. In a study by Marie Cedergren of the Tornblad Institute in Sweden, reported in the June 2003 issue of the Obesity Research journal, obese women who gave birth to infants with congenital heart defects often had undetected, and therefore untreated, type 2 diabetes before pregnancy.

Congenital heart defects are one of the most common types of birth defects, occurring in about 1 out of every 125 pregnancies. Women who are planning pregnancy should strive to achieve a healthy weight and optimal blood sugar control prior to conception.

Sources Include: March of Dimes, The American Heart Association, Congential Heart Defects.com, and the Obesity Research Journal

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