We appreciate the methodologic aspects pointed out by Vinet et al that may have led to a conservative estimate of infertility in women with SLE in our study, particularly with regard to the interpretation of the questions by the participants. In addition, we would like to add that the number of patients with SLE included in the analysis of fertility was small, which may have precluded us from seeing a statistical difference in infertility. Conversely, in our study, 578 women with rheumatoid arthritis (RA) answered the same questions about infertility as the women with SLE. Among women with RA, the rate of infertility was approximately twice as high in those diagnosed prior to completion of childbearing compared to those diagnosed after. Women with SLE, however, reported a similar rate of infertility whether they were diagnosed before or after completion of childbearing. We suspect that women with SLE and RA would interpret the questions about infertility in a similar manner.
Prior studies of women with SLE have found no increase in infertility when compared to a population-based control group, friends, or relatives (1–3). Each of these studies also reported a higher rate of pregnancy loss among women with SLE. Our study found this too, since women diagnosed with SLE before and after childbearing had a similar number of total pregnancies, but those diagnosed earlier had fewer live births.
We agree with Vinet et al that women with SLE have a lower than expected live birth rate. Our study and other studies have suggested that it is not fewer pregnancies, however, that cause this lower live birth rate. Instead, the higher pregnancy loss rate seen in this population is the more likely cause.