Objective: To assess the number of live births in women whose systemic sclerosis (SSc) onset occurred during their reproductive years, and to compare this with general population rates.
Methods: Within the Canadian Scleroderma Research Group cohort, we identified 320 women whose SSc symptoms began prior to age 50 years. We determined the number of children born in the years following first onset of symptoms. We summed the years of followup from the time of first symptoms in subjects up to age 50 years (or oldest age attained, if the subject was age <49 years). We applied age-specific birth rates for Canadian women to these years of followup in order to determine the expected number of live births for the period. We then calculated the standardized incidence ratio (SIR) of observed to expected live births.
Results: In the 320 women studied, the number of live births over the interval since symptom onset was below the expected number (111 live births observed versus 140 expected; SIR 0.79, 95% confidence interval [95% CI] 0.65-0.95). This finding was more prominent in women with diffuse cutaneous disease versus limited cutaneous disease. The mean and median numbers of live births were similar across SSc subgroups based on organ involvement or cyclophosphamide exposure. In repeat analyses, including the reproductive period before SSc symptom onset, the ratio of observed to expected births was 1.23 (95% CI 1.13-1.33).
Conclusion: Compared with the general population, fewer live births were noted in women with SSc, but this phenomenon was only apparent in the period after symptom onset.