It has long been known that obesity is unhealthy and puts us at risk of developing several diseases and health conditions — such as heart diseases, diabetes mellitus, strokes, and hypertension. Obesity by itself is a complex condition that can be related to several causative factors like genetic predisposition, physical activity, and diet patterns.
Being a little overweight, however, is not the same as being obese. The most common index doctors and nutritionists use to classify body weight is the body mass index (BMI), using your weight and height. You can calculate your body mass index by dividing your weight (in kilograms) by your height squared (in m2). A person with a BMI of over 30 is considered to be obese.
Obesity during pregnancy comes with some risks
In pregnant women, obesity can be a cause of several specific conditions that can threaten their pregnancy, such as gestational diabetes mellitus. Gestational diabetes is an abnormal increase in blood sugar levels that starts happening during pregnancy, and requires special attention and close follow up. Another condition is preeclampsia, which translates to dangerously high blood pressure developing during pregnancy and possibly threatening both the mother and child. This latter condition can lead to fatal complications and requires prompt diagnosis and treatment.
Obesity in pregnant women can be problematic for the baby’s health, and can even cause miscarriage. Macrosomia, a condition where the baby is born with an abnormally large size, is associated with maternal obesity. This increases the risk of injury during delivery and makes it more probable for the baby to develop obesity as an adult. Obesity in pregnant women also puts the baby at a higher risk of developing several birth defects, such as neural tube defects or heart defects.
What's the link between maternal obesity during pregnancy and heart defects in babies?
A large Swedish study published last year in the Journal of The American College of Cardiology found that babies born to obese mothers were twice as likely to have certain congenital heart defects when compared to those born to mothers who were not obese. The study analyzed data from over two million births between 1992 and 2012 and found that congenital heart defects happen more frequently in women who have a higher BMI.
Congenital heart defects are anatomical abnormalities caused by the abnormal development of the heart of a newborn and can be a cause of many complications. These defects can be present in up to one percent of newborns and are considered the most common type of birth defects. Many of these defects can remain asymptomatic until adulthood, but some may cause catastrophic consequences to the baby's health.
In the study mentioned above, doctors categorized women into underweight (BMI <18.5) normal weight (BMI 18.5), overweight (BMI 25 to 30), obesity class I (BMI 30 to 35), class II (BMI 35 to 40), and class III (BMI ≥40). They found that 1.4 percent of Swedish newborns had one or more congenital heart defects and that the rate of occurrence of these defects increased as the weight class of the mothers increased. These findings are especially concerning when the rising prevalence of obesity worldwide is taken into perspective.
Two types of congenital heart defects — aortic arch defects, and transposition of the great vessels — were found to be twice more likely to happen in pregnant women with severe obesity.
The two defects affect the large vessels coming out of the heart, called the aorta and the pulmonary artery, and can lead to decreased oxygen levels in the newborn baby.
Patent ductus arteriosus and atrial septal defects are the two other types of congenital heart defects that were also linked to higher maternal BMI. In the former condition, a small vessel called the ductus arteriosus, which normally closes right after birth, fails to close, leading to problems in the heart and lungs. An atrial septal defect, on the other hand, is an abnormal opening and communication between the two small chambers of the heart (the atria).
Many of these diseases are surgically treatable by pediatric cardiac surgeons, however, risks are always involved. Despite this significant association between obesity and the mentioned congenital heart defect, authors of the Swedish study announced that they were not able to find any consistent link between maternal obesity and congenital heart defects other than the four mentioned above.
Obesity is a health burden that puts every affected individual at risk of developing other diseases and adverse conditions. In pregnant women, obesity can be a cause of an unhealthy pregnancy and might put the baby at risk of developing one or more congenital abnormalities. Congenital heart defects, specifically, were recently found to be strongly linked to maternal obesity. Hence, for women considering growing their family soon, losing a little weight before getting pregnant might help ensure a healthier pregnancy and birth.
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