Thursday, January 17, 2008

Homebirth advocates look at gestational diabetes

As I have written before, the standard homebirth advocacy response to pregnancy complications is: Whatever the scientific evidence shows, do the opposite. Here's how it works:

Pregnancy complications: declare that they don't exist.
Screening tests: declare that they don't work AND they cause complications. Insist that they falsely "label" women.
Preventive treatment: Insist that it unnecesary or doesn't work, or both.
Research: Be sure to quote publications for lay people and out of date studies. Don't ever quote the bulk of the research that disagrees.
Histrionics: Insist that doctors have a vested interest in making up complications.

Rixa, at The True Face of Birth, follows the script. She has written two posts in a row on gestational diabetes (Michel Odent on GD and More on GD), both of which are chock full of misinformation and, of course, lack basic information about the topic under discussion.

Let's start by looking at the context for recommendations about gestational diabetes. Despite the histrionics of Dr. Odent, he knows as well as I do that gestational diabetes was not conjured from thin air to make money for doctors. Insulin dependent diabetes mellitus (true diabetes) causes very serious pregnancy complications including congenital anomalies, stillbirth, macrosomia, and shoulder dystocia among other things. Research by endocrinologists and obstetricians has shown that the poor outcomes are directly related to high levels of glucose (blood sugar). Controlling glucose levels as carefully as possible is directly associated with improved outcomes.

Gestational diabetes is not the same disease as diabetes mellitus, but it is related, and it may actually be predictive of future diabetes mellitus in the mother. Both gestational diabetes and diabetes mellitus result in abnormally high blood sugar levels. Reasoning from their experience with diabetes mellitus, endocrinologists and obstetricians were concerned that the high blood sugar levels in gestational diabetes could cause pregnancy complications. Subsequent research has shown that because gestational diabetes does not occur until the second or third trimester (in contrast to diabetes mellitus), it is not associated with congenital anomalies. There does appear to be an increased risk of stillbirth, and there is definitely an increased risk of macrosomia and shoulder dystocia.

Screening women for gestational diabetes has become routine, as well as treating elevated blood sugar levels through diet and exercise, and if that is not successful, through medication. This is just preventive medicine in its most basic form. Who could be opposed to preventive medicine?

Dr. Odent is opposed, naturally. You can read his absurd "paper," Gestational Diabetes: A Diagnosis Still Looking For a Disease? published in his personal "scientific journal". It is classic Odent; it says nothing, helps no one and criticizes obstetricians. It is clearly meant for lay people, with an appropriately intimidating, but meaningless, bibliography. Most of the references are to his own lay publications. In her second post, Rixa references an out of date article from the BMJ, Should we screen for gestational diabetes? The author concludes by recommending more study.

In the intervening years, more study has been done and even more is in progress. Effect of Treatment of Gestational Diabetes Mellitus on Pregnancy Outcomes was published in the New England Journal of Medicine in 2005. The authors conclude:
In this randomized clinical trial, treatment of women with gestational diabetes — including dietary advice, blood glucose monitoring, and insulin therapy — reduced the rate of serious perinatal outcomes (defined as death, shoulder dystocia, bone fracture, and nerve palsy) from 4 percent to 1 percent. These benefits were associated with an increased use of induction of labor for the mother and an increased rate of admission to the neonatal nursery for the infant, both of which may be related to the knowledge of the diagnosis by the attending physician. The earlier gestational age at birth as a consequence of the induction of labor may have contributed to the reduction in serious perinatal outcomes. Others have reported an increased rate of cesarean delivery associated with the diagnosis and treatment of gestational diabetes. In our study, the rate of cesarean delivery was similar in the two groups.
The accompanying editorial, Gestational Diabetes Mellitus — Time to Treat, states:
This study provides critical evidence that identifying and treating gestational diabetes can substantially reduce the risk of adverse perinatal outcomes without, at least in this trial, increasing the rate of cesarean delivery...

Another unresolved question is the level of blood glucose at which intervention is routinely warranted. The glucose levels used to determine eligibility in the present study were different from those currently recommended by U.S. organizations to identify gestational diabetes ... However, target glucose levels during treatment were similar.

Data from two ongoing studies may help guide thresholds for intervention. The Hyperglycemia and Adverse Pregnancy Outcome (HAPO) study is assessing the relationship between glycemia and perinatal outcomes. Another treatment trial is assessing the benefits of tight glycemic control in pregnant women who receive a diagnosis of gestational diabetes on the basis of findings of elevated glucose levels at two points in time after a 100-g oral glucose load but normal fasting glucose levels.

Recent evidence indicates a worrisome rise in the prevalence of gestational diabetes that is largely explained by the increase in maternal obesity. Efforts to reverse this trend are critical. At the same time, the current report by Crowther et al. provides some long-awaited evidence to support the use of screening and treatment for women at risk.
Contrary to the insinuations of homebirth advocates, gestational diabetes causes life threatening complications, the exact magnitude of the complications is being investigated, and research is ongoing to maximize the accuracy of screening and the benefits of treatment. Gestational diabetes is yet another example of the standard homebirth advocacy response to pregnancy complications: while homebirth advocates are busy sneering and helping no one, scientists and physicians are working to reduce preventable neonatal deaths and injuries.

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