Obesity and Birth Defects

The other day, I wrote a post related to rising maternal mortality rates as reported by the National Center for Health Statistics. In that post, I cited obesity as one of the likely contributors to the problem. Today, the Trust for America’s Health (TFAH) foundation released a report, “F as in Fat: How Obesity Policies are Failing in America, 2007.” The results are quite sobering. Obesity, defined in adults as a BMI (BMI = weight in pounds/ height inches x height in inches x 703) > 30, rose in 31 states last year and fell in NONE. Ten of 15 states with the highest rates are in the South. In my own state of South Carolina, the overall rate of adult obesity is now 27.8% (tied for 5th with Tennessee). Accompanying obesity, hypertension is now found in 29.7% and adult-onset diabetes is found in 9.4% of SC state residents. An even more ominous finding is that now, among children ages 10 to 17 in SC, 18.9% are considered overweight (> 95th percentile in weight for age).

Echoing these findings, Dr. James Marks, senior vice president of the Robert Wood Johnson Foundation, which funded the project, commented in a news conference that “The number of states with obesity rates greater than 25 percent has more than doubled in just two years. That's not sending a wake-up call. We're ringing the disaster alarm," he said. "Diseases that used to be considered adult illnesses like type 2 and high blood pressure are becoming increasingly common among children." To put the current epidemic in perspective, in 1991 NO state had an obesity rate in excess of 20%! Jeff Levi, PhD, Executive Director of TFAH, summarized his feelings as follows: “Poor nutrition and physical inactivity are robbing America of our health and productivity.” Indeed, key findings in the report were that “22% of adults admitted to participating in no physical activity and that while every state has school physical education requirements, many are limited in scope or are not enforced.

The statistics above, help to justify the actual reason I sat down to write this post. As part of my comments related to obesity and maternal mortality, one of our residents in OB/GYN couldn’t disagree with my concerns regarding the association of obesity with hypertension, diabetes, and risks for other complications of pregnancy, but challenged my statement regarding the increased risk for fetal abnormalities. Actually, it wasn’t so much a challenge as a request for a specific reference. I did not know one off the top of my head, but the resident wasn’t going to buy my initial response of “in my experience over the last 25 years…” I couldn’t argue the point because these are the days of ‘evidence-based’ medicine and I have to at least try to set a good example. Fortunately, the question was raised on the same day I came a cross an article by Waller and colleagues published earlier this month (Arch Pediatr Adolesc Med. 2007;161:745-50).

In this report, the authors summarized their findings to date from the National Birth Defects Prevention Study, an ongoing multisite case-control study looking specifically at structural birth defects in both overweight and underweight women. Information was gathered from databases in eight states during the time period between October 1997 and December 2002. A clinical geneticist reviewed all cases of birth defects and excluded those found in women with known preexisting diabetes and suspected cases of chromosomal abnormalities or single-gene mutations. An association between congenital abnormalities and obesity was found for spina bifida, congenital heart defects, anorectal atresia, hypospadius, limb reduction defects, diaphragmatic hernias, and omphaloceles with odds ratios ranging from 1.33 to 2.10. It is interesting to note that many of these abnormalities are commonly associated with preexisting diabetes, especially when blood sugar control is poor during the first trimester.

I am not going to speculate on the etiology for the associations at this point. Part of it may be related to previously undiagnosed diabetes or the genetic predisposition for the same, insulin resistance, chronic inflammation, hypercholesterolemia or elevated triglyceride levels, or a host of other problems known to be more common in obese individuals. However, I suspect that a large contribution is simply from the fact that being overweight does not necessarily mean you are in good shape nutritionally. I would not be surprised if studies confirm that levels of folic acid and other vital nutrients that support normal embryogenesis are probably ‘under-represented’ in the obese at the same time certain ‘embryologic toxins’ are present in higher than expected concentrations.

As Dr. Levi from TFAH also pointed out, "If we fail to reverse this epidemic, the current generation may be the first in American history to live sicker and die younger than their parents' generation." With the growing awareness of ‘epigenetic imprinting,’ the condition under which the maternal health status can contribute to the ‘programming’ of the fetus in utero, we may be looking at much more than an impact on the current generation, we may be looking at problems for generations to come!

Labels: congenital anomalies, imprinting, obesity

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