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Jan 10, 2019

Obese Mothers are Twice as Likely to Have a Baby with Congenital Heart Defects

Study confirms the link between maternal obesity and risk of congenital heart defects.

Obesity doesn’t just increase health risks for the mother, based on a recent study that found obese pregnant women are twice as likely to have babies with serious congenital heart defects. Findings were published in the Journal of the American College of Cardiology and highlight the importance of maintaining a healthy weight before pregnancy.

Using a national health registry in Sweden, this study analyzed data from more than 2 million births between 1992 and 2012. The goal was to see whether maternal weight has any impact on a baby’s risk for congenital heart defects.

Congenital heart defects refer to problems with the heart that are present at birth. They’re the most common type of birth defect and affect roughly 8 in 1,000 births. Studies suggest that congenital heart defects are more common in babies with overweight or obese mothers. However, data is sparse, and the association remains unclear, according to authors.

In the recent analysis, researchers found that serious heart defects occurred in 1.4% of 2,050,491 Swedish births. Complex heart defects included a number of conditions including tetralogy of Fallot, transposition of the great arteries, atrial septal defects, aortic arch defects and single-ventricle heart.

After analysis, researchers found that severely obese women were twice as likely to have babies with congenital defects compared to women who were a healthy weight. Overall, risk of certain defects increased with maternal weight, suggesting that the more overweight or obese women are, the greater the risk of having a baby with a congenital heart defect.

In this study, researchers categorized women as normal, overweight or obese based on their first prenatal exam. As authors explain, the appointment usually occurs early enough in pregnancy and provides a general idea of women’s pre-pregnancy weight. In this study, obesity was defined as having a body mass index (BMI) of 30 kg/m2 or greater, while severe obesity was defined as a BMI greater than 35 kg/m2.

What findings show, according to authors, is that risk of having a baby with congenital heart defects increases with obesity. This is a finding that is especially concerning, given drastic rises in obesity rates over the years.

Obesity is generally considered the most important preventable risk factor for pregnancy complications. In Sweden alone, the proportion of pregnant women with obesity nearly doubled between 1992 and 2014. Experts worry about the potential impact of maternal obesity on pregnancy outcomes, such as congenital heart defects.

With additional research, authors hope to better understand the association between obesity and pregnancy outcomes. Authors also emphasize the importance of maintaining a healthy weight, especially for women considering getting pregnant. Achieving a healthy weight before pregnancy can help reduce risk of complications and promote better health for the baby.

Read the full article in the Journal of the American College of Cardiology.

Questions for You to Consider

  • What is a healthy weight for me?
  • A few important tools can be used to determine if an individual is underweight, normal weight or overweight. The easiest tool is a Body Mass Index, which is calculated using height and weight to estimate levels of body fat. However, Body Mass Index is not always accurate, particularly among individuals with extremely high or low amounts of muscle. In these cases, measuring waist circumference is helpful in assessing weight, as a waist circumference greater than 35 inches for a woman or 40 inches for a man is considered unhealthy.
  • What are congenital heart defects?
  • Congenital heart defects refer to a number of different conditions that can occur when a baby’s heart is forming or at birth. Although most defects are found during pregnancy or in early childhood, some defects aren’t discovered until adulthood. Survival rates depend on the severity of the heart defect, but most individuals with congenital heart defects live long and healthy lives.


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Infographic: Obesity

Infographic: Congenital Heart Defects