January 3, 2006

‘Fidgety’ babies of diabetic moms don’t get large

NEW YORK (Reuters Health) - Pregnant women with diabetes
tend to have abnormally large babies, but it seems that active
fetuses manage to stay a relatively normal size, new research

While babies of diabetic women are prone to become overly
big, a condition called macrosomia, it has been unclear why a
substantial proportion do not develop this problem. The
"fidgety fetus hypothesis" has been proposed as an explanation,
suggesting that increased fetal activity can counteract the
macrosomia-promoting effects of the mother's high glucose

As reported in the medical journal Diabetes Care, Dr. Lois
Jovanovic, from Sansum Diabetes Research Institute in Santa
Barbara, California, and colleagues tested this notion in a
three-phase study involving 69 women with gestational diabetes.

In the first phase, involving 10 women, the researchers
showed that fetal movements are pretty consistent from one day
to the next.

The second phase, which included 13 women and involved the
use of a home fetal monitoring device, showed that active
fetuses, defined as having at least 4 heart rate accelerations
in a 20-minute period, are always active, while inactive
fetuses are always inactive.

Finally, in the third and largest phase, involving 46
mothers, the researchers showed that the average birth weight
of the active fetuses was in the 37th percentile, significantly
lower than the 62 percentile for inactive fetuses. Macrosomia
is typically defined as a birth weight heavier than the 90th
percentile for gestational age.

"The fetus appears to play a role in determining its own
destiny," Jovanovic and colleagues write.

They conclude: "Although normoglycemia is the goal of
therapy in all women with diabetes, in those women whose
fetuses manifest less movement, increased surveillance and
treatment of hyperglycemia is of utmost importance."

SOURCE: Diabetes Care, January 2006.