Pregnancy curiosity

Normal 0 false false false MicrosoftInternetExplorer4 Asians have a known increased risk of gestational diabetes, but a new study finds that a pregnant woman in a mixed-race Asian-Caucasian couple also has a heightened risk of the complication, even if she herself is not Asian. The findings suggest a genetic trait at work in such pregnancies.

What’s more, Asian women in these mixed-race couples face an increased risk of delivering a baby by cesarean section, researchers report in the October American Journal of Obstetrics & Gynecology.

Past studies of interracial couples have turned up some curious pregnancy findings. For example, couples in which the mother is African-American and the father Caucasian had an increased risk of pregnancy complications in two previous studies. Meanwhile, another study found that couples in which the mother was Japanese and the father Caucasian showed no increased risk of preeclampsia, a common pregnancy complication.

“It’s a mixed bag,” says Yasser El-Sayed, an obstetrician at Stanford University School of Medicine. “There isn’t a ton of work being done on this.”

That prompted El-Sayed and his colleagues to plow through records of all the Caucasian and Asian couples who had delivered a baby at Lucile Packard Children’s Hospital at Stanford from 2000 to 2005, nearly 10,000 births in all. Ethnicity was self-reported by the couples on medical records.

Women who were part of an Asian-Asian couple were nearly five times as likely to have gestational diabetes as women in a Caucasian-Caucasian couple. But the researchers also found that women who were part of a mixed Asian-Caucasian couple were 2 ½ times as likely to develop gestational diabetes during pregnancy as those in Caucasian-Caucasian couples.

Surprisingly, it didn’t matter which gender in the mixed-race couple was Asian, the records show.

“This is the most interesting finding, and it points toward biological differences in race and ethnicity,” says study coauthor Aaron Caughey, an obstetrician at the University of California, San Francisco.

“It certainly sounds as though there is a nontrivial genetic component” in gestational diabetes, says Cande Ananth, an epidemiologist at the University of Medicine and Dentistry of New Jersey in New Brunswick. “The study also underscores how little we understand as to how genes and environment shape disease risks,” he says.

Meanwhile, the records show that Asian-mother/Caucasian-father couples had pregnancies that resulted in cesarean sections 33 percent of the time, compared with 23 percent among Caucasian-mother/Asian-father couples. Asian-Asian and Caucasian-Caucasian couples fell somewhere between the two kinds of mixed-race couples. Baby weights were roughly standard across the groups.

It could be that Asian women have smaller pelvic size than Caucasians, the authors speculate.

While it’s premature for doctors to use these findings in advising patients in their clinical practices, Caughey says, the data do contribute to a greater understanding of the nuances that govern pregnancy.