NEW YORK (Reuters Health) - African-American women with sickle cell trait are less likely to have preterm delivery and more likely to have multiple gestations than similar women without sickle cell trait, according to a report in the April issue of Obstetrics & Gynecology.

"All women of African-American descent should be offered screening for hemoglobinopathies during pregnancy if this information is not yet available, as there are clear implications for genetic counseling and screening for urinary tract infections in the case of discovery of the sickle cell trait," Dr. Allison S. Bryant told Reuters Health.

"Given the increased risk for multiple gestations," she commented, "physicians may want to be cautious to rule out twin or higher order multiple pregnancies in women carrying the sickle cell trait, as early detection of such pregnancies is valuable to ensure good perinatal outcomes."

Dr. Bryant from the University of California, San Francisco, and colleagues conducted a retrospective study of more than 5000 African-American women who delivered between 1976 and 2001. Of the group, 6.5% carried the sickle cell trait.

Compared to those without sickle cell trait, the odds ratio for delivery before 32 weeks was 0.15 for carriers. Their odds ratio for multiple gestations was 1.94 after adjustment for the use of assisted reproductive technologies, the report indicates.

The decreased risk of preterm delivery was even lower among women with multiple gestations, the report indicates.

"There have been some other associations between carriage of the sickle cell trait and higher gravidity, parity, and more live births," Dr. Bryant noted.

"Some authors have attributed this to ongoing balancing selection of the sickle cell trait even in areas in which malaria is not a threat. Our findings of greater proportions of multiparous women, increased risk of multiple gestations, and a lower risk of preterm delivery among women who carry the trait may fit into this framework," she concluded.