Study: Caesareans increase risk of placenta praevia & abruption
NEW YORK (Reuters Health) May 21 - Women who undergo a cesarean delivery with their first child have an increased risk of placenta previa and placental abruption in a second pregnancy, Canadian researchers report in the May issue of BJOG.
Lead investigator Dr. Quiying Yang told Reuters Health that "more than 1% of pregnancies with a prior cesarean section had placental abruption or placenta previa, which is a 50% increased risk compared to women without previous cesarean section." Dr. Yang of the Ottawa Hospital and colleagues came to this conclusion after examining a U.S. birth and infant mortality database covering 1995 to 2000.
In all, more than 5.1 million singleton second pregnancies were available for analysis.
The team found that placenta previa was recorded in 4.4 per 1000 of second singleton births by women whose first birth was by cesarean section, and in 2.7 per 1000 of second singleton births by women whose first birth was vaginal.
About 6.8 per 1000 second births were complicated by placental abruption in women who underwent a caesarean for their first birth and in 4.8 per 1000 second births by women whose first births were vaginal.
After controlling for factors including age, prenatal care and fetal gender, after a previous cesarean section, the odds ratio for placenta previa was 1.47, and for placental abruption, it was 1.40.
The researchers conclude that because of this "moderately" increased risk, "clinicians might consider this information valuable when they counsel women during pregnancy."
BJOG 2007;114:609-613.
