Thank you for your inquiry.
There is a fairly large body of data regarding the use of aspirin in pregnancy. In small doses such as 81 mg per day, it is safe, although in one study an increased incidence of abruptio placentae was reported (1). With the use of larger doses, and unfortunately I cannot give you the exact milligrams, a number of different side effects have been reported. These include postpartum and antepartum hemorrhage, persistent pulmonary hypertension in the fetus, and oligohydramnios (2, 3).
Based on this, I believe there would be an increased risk of complications at a dose of 325 mg daily.
The use of nonsteroidal drugs in pregnancy has also been associated with adverse events, especially miscarriage (4, 5).
Thus, although one could argue both sides of this issue, in my opinion, the safest tack would be to perform a second desensitization after pregnancy.
Thank you again for your inquiry and we hope this response is helpful to you.
1. N Engl J Med 1993; 329:1213-1218.
2. Fetal Matern Med Rev 1992; 4:37-57.
3. Am J Obstet Gynecol 1993; 168:214-217.
4. BMJ 2003; 327:368.
5. BMJ 2001; 322(7281):266-270.
Phil Lieberman, M.D.