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Sickle cell trait not benign during pregnancy
Researchers observed a threefold incidence in the stillbirth rate among patients with sickle cell trait.
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Patients positive for the sickle cell trait have an increased risk of fetal loss, compared with women with normal hemoglobin levels, according to a recent study.
“The most striking finding was a threefold incidence in the stillbirth rate among patients with sickle cell trait,” said Michelle Y. Taylor, MD, professor in the department of obstetrics and gynecology at the University of Mississippi Medical Center in Jackson.
“The placental findings among women with sickle cell trait differed dramatically from those in the control group, with the rates of amniotic fluid, infection and meconium histiocytosis demonstrating almost a threefold and ninefold increase, respectively,” she said.
Taylor said that the increased signs of infections could be related to the chronic infarctions and sickling, which could lead to subclinical and clinical infections. The current findings are significant, because one in 12 black women carry the sickle cell trait, according to the study.
Comparing specimens
When concurrent with pregnancy, sickle cell anemia, the most common hemoglobinopathy in the Unites States, is associated with increased complications, such as pain crises, fetal loss, maternal infection, preterm labor and intrauterine growth restriction, according to the report, which appeared in the American Journal of Obstetrics and Gynecology.
Previous studies of pregnant women with sickle cell anemia have reported an increased risk of genitourinary tract infections, particularly asymptomatic bacteriuria and preeclampsia.
The researchers have observed that patients positive for the sickle cell trait seemed to have more perinatal loss than previously estimated. They compared obstetric outcomes and placental findings in women with sickle cell anemia with those in women with normal hemoglobin.
Taylor and colleagues complied data on 180 obstetric patients with the sickle cell trait who had been treated at the medical center between 2001 and 2005. They compared these patients with a control group of 189 women with normal hemoglobin and comparable delivery dates. They also analyzed placental specimens for patients and controls.
Increased complications
Women with sickle cell trait demonstrated a shorter mean duration of pregnancy, compared with women in the control group: 233 days vs. 255 days, respectively (P<.001). The mean birth weight of infants born to mothers with sickle cell trait was 2,144 g (4.7 lbs), compared with a mean birth weight of 2,672 g (5.9 lbs) in the control group (P<.001).
“Most importantly, the sickle cell trait group demonstrated an almost threefold increase in the incidence of intrauterine fetal death (9.7%), significantly higher than the rate (3.5%) in mothers with normal hemoglobin,” Taylor said.
Incidence of diabetes and preeclampsia or eclampsia was similar between the patient and control groups. However, the rate of intrauterine growth restriction was higher in the sickle cell group than in the control group: 12% and 7%, respectively.
There were 180 placentas available for pathologic examination in the sickle cell group, compared with 83 placentas in the control group, the researchers said. Fifty percent of the placental specimens in the sickle cell group exhibited evidence of amniotic fluid infections, with 27 specimens having clinical signs of chorioamnionitis. In the control group, 18% of specimens showed signs of amniotic fluid infections. Meconium histiocytosis was prevalent in 91% of the sickle cell specimens, compared with 13% in the control group.
“Furthermore, all placentas of [patients] with sickle cell trait demonstrated sickling in the intervillous space; unexpectedly, sickling was also noted in the decidual vessels, especially the draining of venous channels,” Taylor said. The sickled vessels were often associated with placental infarctions and retroplacental hemorrhages, she said. – by Rebekah Cintolo
For more information:
- Taylor MY, Wyatt-Ashmead J, Gray J, et al. Pregnancy loss after first-trimester viability in women with sickle cell trait: time for a reappraisal? Am J Obstet Gynecol. 2006; In press.