(HealthDay)—Paternal exposure to methotrexate within 90 days before pregnancy is not associated with congenital malformations, stillbirths, or preterm birth, according to a study published in the April issue of Obstetrics & Gynecology.

Lasse Karlsen Eck, M.D., from Copenhagen University Hospital in Denmark, and colleagues conducted a nationwide register study involving all live births in Denmark from 1997 to 2011. A total of 849,676 live births were identified with known paternity. The authors examined the correlation between paternal exposure to methotrexate and and stillbirth in offspring.

There were 127 of methotrexate-exposed fathers. The researchers found that four of these (3.2 percent) had major malformations, compared with 3.4 percent of the unexposed. Among exposed versus unexposed fathers, the odds ratio for major congenital malformation was 0.93 (95 percent confidence interval, 0.34 to 2.51); the odds ratio was 1.01 (95 percent confidence interval, 0.37 to 2.74) after adjustment for year of , maternal age, educational length, household income, and parity. There were no stillbirths in the methotrexate-exposed group compared with 0.3 percent among unexposed fathers; the risk of was not increased among children from exposed fathers (adjusted odds ratio, 1.31; 95 percent confidence interval, 0.66 to 2.59).

"Available data suggest that prepregnancy paternal methotrexate exposure should not be of major concern," the authors write. "Multinational recommendations should be changed accordingly."