Background/Purpose: Outcomes of pregnancy are well studied in a number of rheumatic diseases such as Rheumatoid Arthritis (RA) and systemic lupus erythematosus. When compared, there is very limited data in pregnancy outcomes in patients with spondyloarthritides and in particular ankylosing spondylitis (AS). This study was undertaken to determine the frequency of complications occurring during pregnancy for women with AS and to compare these outcomes with the general obstetric population by using the largest inpatient care database.

Methods: By using the 2003-2011 Nationwide Inpatient Sample of Healthcare Cost and Utilization Project, we estimated the number of obstetric hospitalization, deliveries and caesarean deliveries in women between the age group 18-50 years. Patients hospitalized with AS were identified. Demographic characteristics and in-hospital outcomes were recorded for both AS and control group. Maternal and pregnancy complications for all pregnancy-related admissions for women with and without AS were compared. Multivariate logistic regression analysis was used to obtain adjusted odds ratio (OR).

Results: The total number of obstetric hospitalization was 42.32 million, of which 2538 were women with diagnosis of AS. Mean maternal age of AS population was higher (29.96 years) than the control group (27.32 years). After adjusting for potential confounders, the results in this analysis show that maternal AS population had no significant increase of inpatient mortality or fetal death. Prevalence of preterm delivery and intrauterine growth retardation was also similar among the two groups. Interestingly, the odds of hypertensive diseases and premature rupture of membranes, postpartum hemorrhage and cesarean delivery in AS patients were significantly lower. The results do suggest that AS patients may have a higher risk of antepartum hemorrhage, but the results failed to achieve statistical significance. The frequencies of the above outcomes along with Odds Ratio are provided in Table 1.

Conclusion: Based on our study of national cohort, we conclude that pregnancies in women with AS are relatively safe without any increase in maternal or fetal mortality despite having a higher maternal age. These data are further reassuring that AS patients also do not have higher risk of adverse outcomes of pregnancy than women without AS. This is significantly in contrast to the worse outcomes observed in RA patients in the same analysis and available literature. We suggest that in women with AS, close antenatal and post-delivery monitoring pregnancy be performed but these patients are likely to do well. Further studies are needed to examine these findings in a prospective manner.