Pregnancy in the Interleukin-17/Interleukin-23 Era: Placental Th17 Axis, Maternal–Fetal Risk in Chronic Psoriasis, and Biologic Therapy – A Systematic Review

Understanding how psoriasis, pregnancy immunology, and targeted biologic therapies intersect has become increasingly important as the use of interleukin-17 (IL) and IL-23 inhibitors expands. At the same time, advances in reproductive immunology have shown that the Th17 pathway influences key events in placental development, vascular remodeling, and fetal immune maturation. To explore these connections, we conducted a systematic review of the literature across major databases through January 2025. Of 528 records identified, 35 studies met predefined inclusion criteria. Although heterogeneous in design, the available evidence demonstrates that IL-17 and IL-23 activity is detectable within the placental environment and is amplified in conditions such as preeclampsia and placental insufficiency. Experimental and translational studies suggest that IL-17 may traverse placental membranes, influence trophoblast behavior, and contribute to inflammatory signaling at the maternal–fetal interface. Clinical studies involving women with psoriasis or psoriatic arthritis indicate that heightened Th17-related inflammation may be associated with less favorable pregnancy outcomes, although findings vary and are frequently limited by small sample sizes. Reports describing pregnancy exposures to IL-23 inhibitors are few but generally reassuring, whereas data on IL-17 inhibitors remain sparse and do not yet allow firm conclusions about safety. Across the literature, gaps in methodology, limited follow-up, and inconsistent reporting restrict the strength of inference. Taken together, current findings point to an immunologic pathway that may have greater relevance to pregnancy than previously appreciated and highlight the need for prospective, mechanistically informed research that can better guide therapeutic decisions for women of reproductive age.