Objective: We aimed in this study to evaluate the impact of maternal interleukin -17A and the activity of the illness on pregnancy outcomes in Psoriatic arthritis (PsA) and ankylosing spondylitis (AS) patients. Methods: This prospective cohort research was carried out on 48 Psoriatic arthritis and ankylosing spondylitis pregnant women attending the inpatient and outpatient clinics of Rheumatology & Rehabilitation and Obstetrics & Gynecology Departments, Faculty of Medicine, Zagazig university hospitals in Egypt and Yanbu National Hospital in KSA and 30 apparently healthy age- and sex-matched pregnant women between January 1,2018, and December 31, 2019. Results: The study group patients have higher risk of preterm labour (32‐36 weeks’ gestation) (aRR 1.80, 95% CI 0.79–4.17), oligohydramnios (aRR 3.15, 95% CI 1.26-8.42), Caesarean delivery (aRR 1.57, 95% CI 1.41-2.68), and delivering infants small for gestational age (aRR 7.04, 95% CI 2.36-12.42). There was significant difference between the control group and the study groups regarding the level IL-17A. Conclusion: A lot of females with PsA and AS have uninhibited pregnancy as regards adverse events, but in comparison with normal pregnancies particularly with high IL-17A during third trimester we noticed a growing risk of preterm labour, oligohydramnios and caesarean section.