Page 70 - Fertility in Women with Rheumatoid Arthritis Vruchtbaarheid van vrouwen met reumatoïde artritis

Chapter 4
MTX, a folic acid antagonist, can be a disruptor of fetal development, and therefore it can potentially increase the miscarriage rate. However, a recent study on pregnancy outcomes after MTX use showed that there was no increased risk of miscarriage after preconceptional MTX use.16 To be eligible for the PARA study, patients who had been taking MTX had to stop the drug at least 3 months before trying to conceive. Therefore, it is unlikely that MTX itself has a causal relationship with the occurrence of miscarriage in this cohort.
The percentage of patients who had a flare of RA within 6 or 12 weeks after their miscarriage was comparable to the percentage of patients with a flare after delivery.1 However, patients who miscarry do not bene t from the attenuation of RA that often occurs in the second and third trimesters of pregnancy.1 Furthermore, many patients who delivered subsequently restarted or intensi ed antirheumatic drug treatment, whereas patients who had a miscarriage often could not be treated optimally, because they were again actively trying to conceive. Because of the increase in disease activity in a period of less- intensive antirheumatic treatment, flares after miscarriage may result in not only disability and long-term joint damage but also reduced fertility.2
Although the PARA study is thus far the world’s largest prospective cohort on pregnancy in RA, the associations found did not reach statistical signi cance due to the relative low frequency of miscarriages in the study. This also limited the possibilities for multivariate analysis. Nevertheless, this is the only known cohort of female RA patients with clinical information, such as medication use and disease activity scores, available during the preconception period. Since the presence of ACPA, past use of MTX, and disease activity scores all tend to be associated with the occurrence of miscarriage, it is plausible that RA patients with more severe disease have a higher risk of miscarriage.
In conclusion, miscarriage rates in RA patients are comparable to those in the general population. The observed associations between miscarriages and the presence of ACPAs, disease activity, and MTX use were not signi cant. Within 1 year after miscarriage, the majority of patients who continued trying to conceive achieved a pregnancy resulting in a live birth.
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