How Low Birth Weight Affects Child Health

Low birth weight can affect a child in different ways later in life. Developmental disorders are just as likely as an increased risk of metabolic and cardiovascular diseases. Certain factors can affect birth weight. These include, for example, placenta dysfunction, chronic illnesses in the mother, but also a negative lifestyle during pregnancy, such as alcohol and nicotine consumption and poor nutrition.

Low Birth Weight and Risk of Autism

Links between low birth weight and a range of motor and cognitive problems have long been known, and in fact research has found that children with low birth weight are also at increased risk of developing autism spectrum disorders (ASD). Autism researchers at the University of Pennsylvania School of Nursing have found a link between low birth weight and children diagnosed with autism, reporting that preterm infants are five times more likely to have autism than children born of normal weight. The infants were born between September 1984 and July 1987 in the counties of Middlesex, Monmouth and Ocean in New Jersey with a birth weight of 500 to 2000 grams or a maximum of 4.4 pounds.

Low Birth Weight and Heart Health

Children with a low birth weight also have an increased risk of developing heart problems. While scientists in the past primarily used birth weight for assessment, more recent studies have shown that the PI or BMI is a much more meaningful tool.

In fact, it’s a newborn’s ratio — a measure that includes both birth weight and height — that doctors can best tell if a child will be born with an increased risk of heart problems later in life. Measurements called the Ponderal Index or PI, as well as the widely used body mass index or BMI, which take into account both height and weight, are likely to provide a more accurate indication of fetal growth and the child’s future. The Ponderal Index, also known as the Rohrer Index, is a measure of body weight (physically correct, body mass) in relation to height, similar to the body mass index. BMI accounts for length by dividing birth weight by birth length to the power of 2, while PI gives length even more importance by using the power of three. Research at the Medical College of Georgia and Children’s Hospital of Georgia at Augusta University shows that a low PI or low BMI at birth, similar to high cholesterol or high blood pressure, should be considered a risk that requires attention and intervention.

Ponderal Index and BMI: More Accurate Tools for Determining Cardiac Development

Perinatal growth – which is influenced by numerous factors, from genetics to environmental factors such as maternal health and habits such as smoking, diet and gestational diabetes – is known to have important implications for heart development. Researchers hypothesized that a baby’s PI, or BMI, at birth would provide a much better indicator of heart development and future function than birth weight alone. They found in a group of 379 healthy adolescents that a low PI — in which growth in height and weight is out of sync during development — was most strongly associated with an increase in the size of the heart’s pumping chamber, the left ventricle of the heart, which as a risk for future cardiovascular diseases. The results suggest that factors affecting fetal growth may also alter cardiac development, changes that can have a lasting, negative impact on adult heart function and cardiovascular health.

For this study, the researchers followed 379 healthy black and white youth, ages 14 to 18, from the Augusta, Georgia area. Parents reported their children’s birth weight and height, which researchers used to calculate a BMI and PI. Two-dimensional echocardiography was used to noninvasively examine the children’s left ventricle for telltale signs of hypertrophy, such as thickening of the walls and less blood being pumped out.

Then, in what appears to be the first study, they examined the connections between birth weight and birth BMI and PI, as well as the structure and function of the children’s left ventricle. Other measures have also been taken, such as the Tanner scale, which looks more closely at puberty development. Researchers also assessed factors such as socioeconomic status and physical activity. At the time of follow-up, 25 percent of the adolescents were overweight or obese. An approximately 40% increase in visceral obesity was also noted. This is fat around the abdomen and the organs in the abdominal cavity, which is considered particularly unhealthy. These children were also much more likely to have higher systolic blood pressure. Laboratory animal studies show that heart mass is primarily determined at birth and the production of heart cells, or cardiomyocytes, that make up the heart declines rapidly after birth, so the heart cells you are born with, must enlarge in order to get bigger what is known as hypertrophy. Enlargement of the left ventricle typically results from the heart having to work too hard against, for example, high pressure in the blood vessels, and can lead to heart failure.

Also Increased Risk of Diabetes

The risk of other chronic diseases, such as obesity and diabetes, has also been linked to low birth weight. Studies show that people born weighing 4 pounds or less are at increased risk of developing type 2 diabetes as adults. Research not only confirms this risk in a sample of more than 3,000 women, but also shows the relative predictive value of different biomarkers and gives physicians potential new tools to understand individual risk in women with low birth weight. The study, published in the journal Diabetologia, drew on the detailed medical records of participants in the Women’s Health Initiative, a large study supported by the National Heart Lung and Blood Institute. The team focused on 1,259 women who developed type 2 diabetes and 1,790 otherwise similar women who did not develop the disease. Overall, the data showed that low birth weight (less than 6 pounds )means a 2.15 times greater risk of developing type 2 Diabetes compared to women born at 8 to 10 pounds. The study also examined the percentage relative predictive value of various easily measurable biomarkers. Among them, insulin resistance contributed the most (47 percent), which is not surprising since insulin resistance is a core component of diabetes.

Despite these results, however, the cardiovascular system seems to be particularly affected by perinatal growth, according to researchers. In fact, the baby’s heart has started developing by the fifth week, and it is during this critical period of development that the child is most at risk of birth defects, which are due to factors such as the mother’s alcohol consumption and some medications. This research underscores the importance of adopting a healthy lifestyle during pregnancy to prevent low birth weight.