Previously, there has been no conclusive data that has demonstrated a consistent pattern of disease activity in pregnant women with axial spondyloarthritis (axSpA.) Some studies have seen an increase in disease activity in pregnant women; others have seen decreases; and some have reported that there is no difference at all compared to healthy women. A recent study out of Norway sought to come to a definitive conclusion using proven scientific methods, such as the BASDAI, BASFAI and CRP.
The study was conducted on a pool of 166 pregnant women (179 total pregnancies), gathered from the RevNatus nationwide register – a Norwegian database of women with inflammatory rheumatic disease, tracking women starting with the planning of pregnancy through 12 months postpartum. Disease activity was then evaluated over the course of seven different time frames throughout the pregnancy as well as postpartum for comparison.
Disease Activity Changes
The study found that, even though the overall BASDAI score was highest during the second trimester (13-27 weeks of pregnancy) and the BASFI was highest during the third trimester (28 weeks to birth), disease activity overall was predictable and stable throughout the study. As expected, both BASDAI and BASFI were lowest at 12 months postpartum while CRP levels remained low throughout the study, indicating that there is no decisive relationship between CRP levels and pregnancy stage. In conclusion, the study showed a slight increase in disease activity during the second trimester, but, in general, was relatively low throughout the entire duration of pregnancy.
Additional data regarding NSAIDs, prednisone, biological medications, and other drugs was also recorded. One fifth of the study pool reported using NSAIDs during pregnancy with the most usage being reported during the second trimester – the same stage with the highest overall BASDAI score. Women on prednisone also had higher disease activity than those not using the medication, with the highest rate of usage occurring during the third trimester. 44% of women used a biological medication, (a TNFi) prior to pregnancy, but only 5% reported using it during pregnancy – likely in large part due to the condition that no biological medication is approved in Norway as of this writing for pregnant women.
On a related note, as of March 22, 2018, CIMZIA (certolizumab pegol) became the first FDA approved biologic in the U.S. to have pharmacokinetic studies added to their label showing “negligible to low transfer” of the medication through the placenta in pregnant women, and “minimal transfer” to breast milk in nursing women. This is an important advancement that may allow some women to better manage their rheumatic condition during their pregnancy and while nursing. CIMZIA has not yet had European approval for use in pregnant women, though smaller preliminary European studies seem to demonstrate an acceptable safety profile as well. CIMZIA is approved for nursing women in Europe.
Despite the slight increase in BASDAI and BASFI during certain trimesters, there was no statistical evidence to suggest that this was caused by an increase in disease activity. In total, almost 70% of women did not take medications for their rheumatic disease during their third trimester compared to <20% pre-pregnancy and 13% postpartum. It can be argued that this increase in discomfort can be attributed to the sudden decrease in pain-alleviating medication intake or biological/biomechanical changes that naturally occur during pregnancy. This is further supported by the low values of CRP throughout the duration of the study. Additional studies will need to be conducted in order to provide an objective assessment of inflammation and the correlation between biological pregnancy changes, scientific measures, and medications
To conclude, the authors found that “the majority of pregnant women with axSpA experienced stable, low disease activity. In accordance with two previous studies, we found a small increase in disease activity in the second trimester. Future research on pregnancy in women with axSpA should differentiate between subgroups of the disease and aim to include objective assessment of inflammation.”
 The Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) ) is a quick and subjective measure in which patients classify their discomfort level on a scale of 1-10 in 6 different categories, such as fatigue and stiffness, and then the numbers are averaged.
 The Bath Ankylosing Spondylitis Functional Index (BASFI) is a quick and subjective test that rates a patient’s confidence in their ability to complete certain activities or tasks, such as putting socks on or standing unsupported for 10 minutes without discomfort.
 The C-reactive Protein (CRP) test is a blood test that identifies the amount of CRP in a patient’s blood. High levels of CRP indicate high rates of inflammation and is frequent in patients with active axSpA or AS symptoms.
Sources Used, and Further Reading:
“Disease activity during and after pregnancy in women with axial spondyloarthritis: a prospective multicentre study” [ABSTRACT]
“Disease activity during and after pregnancy in women with axial spondyloarthritis: a prospective multicentre study” [FULL STUDY]
“CIMZIA® (certolizumab pegol) label update marks major advance for women of childbearing age with chronic inflammatory disease in the U.S.”