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Obesity and Pregnancy: A Dangerous Duo
The unfortunate "state of the weight" in the United States is that over the past 50 years, the number of Americans classified as overweight or obese has climbed from 13% to two-thirds. Of particular importance to women's health care practitioners is the fact that more than 40% of pregnant women are either overweight or obese.
The Body Mass Index (BMI) is a simple formula that combines an adult person's height and weight to determine if their body fat content is in the normal range (BMI of 18.5 - 24.9) or overweight (BMI of 25.0 - 29.9) or obese (BMI above 30, and BMI above 40 is extremely obese). The BMI categories overweight and obese are both associated with an increased risk for adverse health consequences.
Obesity has long been perceived as a risk factor in pregnancy. Research over several decades has demonstrated consistently that obese pregnant women are at risk for a multitude of adverse outcomes for the mother, the baby while it is in the womb, and the newborn baby. The recent rise in the U.S. maternal mortality rate has been attributed in part to the rise in obesity among pregnant women. In those states that have compiled data on this problem (Florida, Virginia), profound increases in the risk for maternal death have been associated with obesity.
While the mother is pregnant, obesity raises her risk for these pregnancy complications: gestational diabetes, high blood pressure during pregnancy, excessive and unhealthy growth of the baby in the womb, birth defects, prolonged labor, injuries to the baby during the birth process, the baby may get stuck trying to come out of the birth canal, the need to intervene in vaginal births to extract the baby with either forceps or vacuum extraction, the need to deliver the baby by C-section surgery, and post-delivery complications for the mother of excessive bleeding, blood clots in the legs, lungs and heart, and higher rates of infection.
Mounting evidence now suggests that the children of obese mothers are at greater risk for lifelong complications that include adult onset of diabetes, heart disease, and obesity. This is believed to occur through a mechanism called "in-utero programming" of the developing baby's metabolism.
Physicians encourage pre-natal counseling for women of reproductive age who are obese. They should be encouraged to lose weight and achieve a BMI in the normal range prior to conception. Daily intake of a multivitamin with a minimum of 400 mg of folic acid is also recommended for all women of reproductive age capable of achieving pregnancy, to reduce the risk of neural tube defects.
Unfortunately, many overweight and obese women do not prepare for pregnancy by losing weight. By the time their pregnancy is diagnosed, the baby has already been exposed to the potentially "toxic metabolic environment" that is seen in the womb when obesity and pregnancy go together. Moreover, the degree of weight loss required to substantially modify important health parameters (blood pressure, blood glucose and lipid levels) cannot occur safely in pregnancy without concern for the baby. It cannot be overstated that the ideal time for intervention is before conception.
In conclusion, the care of the obese pregnant woman can be extremely challenging and pregnancy outcomes are more often compromised. Achieving a normal BMI prior to pregnancy is highly recommended. For those women who are obese during pregnancy, especially those defined as extremely obese (BMI above 40), prenatal care with an obstetrician or Maternal-Fetal Medicine specialist with experience in the management of obesity in pregnancy is a necessity. Heightened surveillance for complications of pregnancy will hopefully achieve the very best pregnancy outcome possible under these circumstances. We have included a list of suggested reading for physicians.
As prevention is always the hallmark of the best medical approach to disease management, obese women contemplating pregnancy are encouraged to seek preconception counseling. This will give them the opportunity to make informed decisions regarding pregnancy based upon an individualized risk assessment. Patients should understand that the discussion of this somewhat sensitive topic is undertaken with the intent of improving the mother's health and that of her child; this is not an issue of aesthetics, but one of health status improvement. Hopefully the provider and patient will build a rapport that will allow for appropriate follow-up counseling on weight loss opportunities - be they behavioral, medical, or surgical. Truly, any impact made in this regard has the potential for tremendous health benefit not only in pregnancy, but over the entire life of the mother and her child.