THURSDAY, April 23 (HealthDay News) -- Although the rate of complications during pregnancy has remained unchanged since 1993, the percentage of pregnant women with preexisting conditions, such as high blood pressure and diabetes, has increased, a new study finds.
The scientists speculated that the increase was driven by more obese women and more older women having babies. Both obesity and the mother's age have been linked to increased complications during pregnancy and delivery, according to researchers from the U.S. Centers for Disease Control and Prevention.
"There's the good news and the bad news," said study co-author Dr. William Callaghan, a senior scientist in the CDC's Maternal and Infant Health Branch in the Division of Reproductive Health. "The good news is that we are seeing some improvements. The bad news is that some of the traditional complications of pregnancy -- hemorrhage and hypertension -- are increasing."
Why these problems are on the rise is not clear, Callaghan said. "It would be great to understand why and, to the extent they are preventable, prevent them," he said.
The report is published in the May issue of Obstetrics & Gynecology.
For the study, Callaghan and his CDC colleagues used data from the National Hospital Discharge Survey to estimate the rate of pregnancy and delivery complications, including preexisting medical conditions and cesarean delivery. They compared data from 2001 to 2005 with data from 1993 to 1997.
They found that the overall rate of delivery complications held steady at 28.6 percent. However, the prevalence of preexisting medical conditions among women delivering infants increased, from 4.1 percent to 4.9 percent.
High blood pressure, preeclampsia, diabetes, asthma and bleeding after delivery all increased, raising concern among the researchers. "This is something we are not going to see go away," Callaghan said.
"There is no question hypertension is increasing," he said. "Again, it is unclear exactly why. We know it is associated with older women, we know it is associated with first pregnancy and we know that there are more older women having first pregnancies."
But obesity, which is also associated with high blood pressure, is increasing and may be a reason as well, he said.
At the same time, the rate of lacerations from episiotomy decreased, the study found. This may have something to do with the increasing number of cesarean deliveries, Callaghan said.
The rate of cesarean delivery increased, from 21.8 percent from 1993 to 1997 to 28.3 percent from 2001 to 2005, the researchers reported. The reason for this increase is also unknown, Callaghan said.
"It may reflect an increase in the risk status of women who are getting pregnant, especially older women and women who are coming into pregnancy with chronic diseases," he said. "It also reflects changes in practice patterns and how physicians make decisions about when a cesarean is warranted."
Dr. Edmund F. Funai, chief of obstetrics at Yale University School of Medicine, said he thinks the authors were "spot-on in their conclusions."
"While studies derived from administrative data must be interpreted with caution, it is very true that more births are occurring in older women than ever before," Funai said. "One natural byproduct of aging is the likelihood of accruing chronic disease diagnoses, such as hypertension. Compounding this fact is the rise in the prevalence of obesity, which itself is associated with morbidities such as hypertension and diabetes. The effect of aging and obesity is also likely synergistic."
However, classifying cesarean delivery as morbidity does not seem to be seem relevant any longer, Funai said.
"Many patients and providers are more interested in being able to schedule a birth, rather than awaiting spontaneous labor," he said. "Also, an increasing number of women seem to be most interested in maximizing fetal safety via cesarean, even if it means a disproportionate maternal risk as a trade-off. This is a cultural shift among patients that is still evolving."
The U.S. National Women's Health Information Center has more on childbirth.
SOURCES: William Callaghan, M.D., M.P.H., senior scientist, Maternal and Infant Health Branch, Division of Reproductive Health, U.S. Centers for Disease Control and Prevention, Atlanta; Edmund F. Funai, M.D., associate professor and chief, obstetrics, Yale University School of Medicine, New Haven, Conn.; May 2009 Obstetrics & Gynecology