I have always been fascinated by this body of research linking low-birthweight (LBW) with adult chronic diseases. Low birth weight is defined as a baby born weighing less than 5 lbs. 8 oz. The most common reasons are preterm birth (before 37 weeks of gestation), high rates of multiple births, high-tech methods that help these babies survive, and trends of delayed childbearing resulting in more complications making LBW more prevalent. The incidence of LBW babies has been rising. Since 1990, the U.S low-birthweight rate increased by 19% and the preterm birth rate has risen 21%
Among the countries of the world, the U.S. ranks 29th in terms of infant mortality rate and is associated with infants with low-birth weight or preterm infants. U.S. has a rate of 6.9 deaths per 1,000 live births compared to Singapore with 2.0. The top three countries with low infant mortality rate are Singapore, Hong Kong, and Japan. Hungary, Poland, Slovakia rank just above the U.S. thus comprising the bottom four. One in 12 U.S. infants is born too small, and over 1 in 8 is born too early.
There are critical periods of growth and development during fetal life during which all essential nutrients needed for growth and development must be available or growth and development will not proceed normally. Even an excess of certain nutrients can have profound influences. For example, the hard palate (roof of the mouth) is formed early in the third month of pregnancy. If excessive amounts of vitamin A are present in the fetal tissues during this period, the two plates may fail to fuse together.
The fetal origins hypothesis concerns the potential effects of maternal nutrition on the baby’s risk of developing certain chronic diseases later in life. It appears that chronic diseases such as heart disease, stroke, diabetes, obesity, hypertension may be “programmed” or gene functions modified, by inadequate or excessive supplies of energy or nutrients during pregnancy.
There is a myth that the fetus is a parasite and will simply draw whatever nutrients it needs from the mother at the expense of her health. If the mother provides only enough nutrients to maintain her health, nature protects the producer – necessary for survival of the species. Based on this theory, the baby loses.
Chronic inflammation is now thought to be involved with promoting chronic disease. It is now thought that lower weight at birth may increase inflammatory processes in adulthood, which can lead to heart disease and diabetes.
A study followed 5,619 children born in 1966 until adulthood. Those people with lower birth weights had a higher number of white blood cells than people with normal birth weights (7 pounds, 11 ounces to 8 pounds 13 ounces). The presence of higher white blood cell counts indicates the possible presence of infectious disease or chronic inflammation.
“Our findings suggest that the link between poorer growth early in life and these adult chronic diseases may involve inflammation as a common underlying factor”, said Dr. Dexter Cancy, MD, PhD of the University of Manchester in the U.K., the lead researcher of the study. Most of the research in this area has been done in Great Britain.
Weight at birth and infancy in relation to adult leukocyte count: a population-based study of 5,619 men and women followed from the fetal period to adulthood. Journal of Clinical Endocrinology & Metabolism June 2009.
Another study suggests that LBW babies develop less neurons in the region of the brain (hypothalamus) associated with control of food intake when compared with normal weight babies. So some people are “programmed” early in life to possibly overeat later in life due to underdevelopment in fetal life. This may reflect poor nutrition in pregnancy resulting in poor weight gain of the fetus.
Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center (LA BioMed). “Why low birth weight is linked to obesity later in life: Study provides explanation.” ScienceDaily 12 March 2011. 24 March 2011 <http://www.sciencedaily.com /releases/2011/03/110310070311.htm>.
No one knows for sure what impact these findings have concerning obesity, heart disease, stroke, diabetes, or even cancer. But it certainly supports the saying: “We are what we eat” or in this case, “we are what our mothers ate”. This places an even more important emphasis on maternal nutrition, especially during the first few months of pregnancy.