It is the proportion of a newborn – a measure that includes both birth weight and length – that may best tell doctors if a child is born with an increased risk of heart problems later in life, investigators report.
Birth weight, though important, tells only part of the history of fetal growth, while the additional consideration of length gives a more complete picture of both fetal growth and growth trajectory, says Dr. Brian Stansfield, a neonatologist at the Georgia Medical College. Hospital of Georgia at Augusta University.
Measures called the weight index, or PI, as well as the more widely used body mass index, or BMI, which both calculate height and weight, probably give a more accurate indication of fetal growth and what's ahead for the child, says Stansfield, a corresponding author. of the study the newspaper Early Human Development.
The new study indicates that low PI or low BMI at birth, as well as high cholesterol or high blood pressure, should be considered a risk that requires attention and intervention, says Stansfield, who is also a research clinician at MCG's Vascular Biology Center.
Historically, birth weight has been a focus of studies linking early life to subsequent health consequences.
When you look at birth rate alone, you look at measurement at a single time, which is a big problem when it comes to projecting. "
Dr. Brian Stansfield, neonatologist, Georgia Medical College and Georgia Children's Hospital at Augusta University
It is known that perinatal growth – which is affected by multiple factors, from genetics to environmental, such as maternal health and habits such as smoking, nutrition and gestational diabetes – has important implications for heart development, and animal and human studies have associated low birth weight with heart problems and death.
MCG investigators hypothesized that a baby's PI or BMI at birth would provide a much better indicator of cardiac development and future function than just birth weight.
They found in a group of 379 healthy adolescents that low PI – where increases in height and weight decline during development – were most associated with an increase in the size of the heart's main pumping chamber, left ventricle, which is considered a risk for future cardiovascular disease. disease.
The findings further suggest that factors that affect fetal growth may also alter cardiac development, changes that may have a persistent, negative effect on heart function and cardiovascular health as adults, they write.
They also indicate that proportionality can help differentiate babies who are born small because of their genetics – smaller parents tend to have smaller babies, for example – and those who fail to reach their in-utero growth potential for other reasons.
"What we're trying to do is figure out how to categorize those children at birth so that we know who to look at in more detail and ideally intervene earlier to help offset some of these risks," Stansfield says.
While his study found that low PI has the highest association with risk factors for heart problems, the more widely used BMI is also a good tool, he notes. BMI reports length, dividing birth weight by birth time to second power, while PI gives length even more emphasis by using power of three.
"We believe that our findings are a call for pediatricians to be even more diligent in measuring and noticing birth pulse and length parameters," Stansfield says of his typically very advanced colleagues. They are also a call to adult primary care providers to realize that this very early measure of height and weight can provide a lifelong understanding of individual heart risk and other diseases, he says. Digital health records should help physicians and patients alike find and keep these early statistics and ideally intervene before problems begin, he notes.
Additionally, they are another reminder to mothers-to-be of abstinence from smoking, alcohol and drugs; eat right; and exercise safely during pregnancy in an effort to ensure a healthy environment for their developing child, Stansfield says. He realizes that even the genetics that a baby inherits can be changed for better or worse by what he experiences during development.
Risks to health problems like heart disease are a conflict of genetics and environmental risks and those environmental risks also start in utero, he says.
For this study, they looked at 379 healthy black and white adolescents aged 14-18 from the Augusta, Georgia area. Parents provided the birth weight and length of their children, which were used by respondents to calculate BMI and PI.
Two-dimensional echocardiography used to noninvasively look at the left ventricle of the children to tell indicators of hypertrophy such as thickening of the walls and less blood being pumped.
Later, on what appears to be the first study to do so, they looked at relationships between birth weight and birth BMI and PI and the structure and function of the left ventricle in children.
Other measures have also been made, such as the Tanner scale, which looks at pubertal development in more detail. The respondents also assessed factors such as socioeconomic status and physical activity, including the children wearing monitors to track physical movement for seven days.
Stansfield notes that at the time of their follow-up for this study, about 25% of adolescents were overweight or overweight and most were on a higher trajectory with their BMI, which is not good.
Children with a higher trajectory were about 30% more likely to become obese compared to those with a lower trajectory, who were about 5% more likely.
There was also a 40% increase in visceral adiposity – fat around the belly and organs in the abdominal cavity, which is considered particularly diseased – in adolescents with upward and downward BMI trajectory. Also, these children were much more likely to have higher systolic pressure – the maximum number of blood pressure that indicates the pressure in arteries when the heart contracts.
While more work is needed to put all the pieces together, proportionality could also help identify babies who seem, at least at birth, to be headed for good heart health, Stansfield says.
Animal laboratory studies indicate that heart mass is largely determined at birth, and the production of heart cells, or cardiomyocytes, which make up the heart rapidly decreases after birth, so in order to grow, the heart cells with which you are born must increase, called hypertrophy. , which is not considered normal growth. Enlargement of the left ventricle typically results in the heart having to work too hard against, for example, high blood pressure, and can result in heart rate.
MCG investigators reported last year in the journal Pediatric Research that fetal growth restriction in guinea pigs suppresses the production of and increased cardiomyocyte death, leading to hypertrophy of cardiomyocytes, which were present and other disruptions to the normal architecture of the heart.
The risk of another chronic disease, such as obesity and diabetes, has also been linked to low birth weight, but the cardiovascular system seems particularly affected by perinatal growth, the researchers say. In fact, by week five, the baby's heart began to develop, and during this critical period of development the baby is most at risk for birth defects from factors such as alcohol consumption by the mother and some medications.
Medical College of Georgia at Augusta University
Reference journal reference:
Sawyer, A.A. et al. (2019) Proportion at birth and left ventricular hypertrophy in healthy adolescents. Early Human Development. doi.org/10.1016/j.earlhumdev.2019.03.018.