Clinical bottom line

There is no evidence that aspirin use in the first three months of pregnancy results in any increased risk of congenital abnormalities.

Reference

E Kozer et al. Aspirin consumption during the first trimester of pregnancy and congenital abnormalities: a meta-analysis. American Journal of Obstetrics and Gynecology 2002 187: 1623-1630.

Meta-analysis

A very considerable search was undertaken for studies of any architecture that examined the use of aspirin in pregnancy and congenital abnormalities. Five electronic databases were searched, and texts and bibliographies were also examined for studies.

Results

Twenty-two studies were identified, one randomised study and the others case control or cohort studies. The main results are shown in the Table. There was no association between aspirin use and overall abnormalities, but there was a small increased risk for gastrochisis in a small number of women.

Table 1: Results of meta-analysis

Comment

Overall there was no evidence of any association between maternal aspirin ingestion in the first trimester and congenital abnormality in the infant. Gastroschisis (imperfect closure of the abdomen) may be associated with an increased risk, but the numbers were small and much larger (at least 20 times) number would need to be studied to be certain of this. This abnormality affects perhaps 3-6 per 100,000 births. The studies did not have confirmed diagnosis, and maternal disease may have contributed to the result observed.