In women with diabetes, increasing hemoglobin A1C levels early in pregnancy - an indicator of poor blood sugar control - are associated with increasing risk of poor pregnancy outcomes, according to a report in the journal Diabetes Care.
Lowering of hemoglobin A1C “seems to be associated with a reduced risk of adverse fetal outcome,” Dr. Gunnar L. Nielsen told Reuters Health.
Nielsen and colleagues from Aalborg Hospital, Aarhus University Hospital, Aalborg, Denmark investigated the usefulness of first-trimester A1C level in predicting adverse outcomes in 537 pregnancies in women with insulin-dependent diabetes.
Hemoglobin A1C levels averaged 7.4 percent in pregnancies with a good outcome, the team reports, compared with 8.5 percent in the 165 pregnancies that had an adverse outcome, ending in spontaneous or therapeutic abortion, stillbirth, neonatal death, or birth defect.
There was a consistently positive, almost linear association between increasing hemoglobin A1C levels and the risk of adverse pregnancy outcome beginning at an A1C level slightly below 7.0 percent, the results indicate. The American Diabetes Association recommends a target A1C level of 7.0 or lower.
Each 1 percent increase in hemoglobin A1C corresponded to a 5.5 percent increase in risk of having an adverse outcome.
However, A1C was not very helpful in predicting outcome of individual pregnancies. For example, 21 percent of pregnancies with A1C above 10 percent had a good outcome, while 15 percent of pregnancies with A1C less than 6 percent had an adverse outcome.
“Although the association between hemoglobin A1C and outcome intuitively seems to be strong, it is obvious that other factors must be in play,” Nielsen said.
SOURCE: Diabetes Care, December 2006.
Revision date: June 11, 2011
Last revised: by Janet A. Staessen, MD, PhD