The influence of systemic lupus erythematosus (SLE) on pregnancy and vice versa was examined during 39 pregnancies in 19 patients, and outcome was compared with 24 pregnancies in 18 other patients before SLE was established. No difference in fetal loss or premature birth rate was found, although more babies were born with low birth weight after SLE was diagnosed; there was a preponderance of female babies in both groups. Pregnancy during SLE was accompanied by disease exacerbations in up to 74% of all patients. These exacerbations concerned mostly musculoskeletal (41%) and hematological abnormalities (36%), while organ involvement occurred in 13% of all exacerbations. No differences in pregnancy outcome during SLE were found between patients with active or quiescent disease, as established by the lupus activity criteria count (LACC). The presence of antibodies to SSA in the mother was associated with the occurrence of congenital heart block; no association was found between antiphospholipid antibodies and fetal loss.