OBJECTIVE: Non-functioning pituitary adenomas (NFPAs) are a group of hormonally inactive adenomas. The aim of this study was to investigate the possible effects of NFPAs on pregnancy. MATERIAL AND METHODS: Thirty patients with NFPAs and without hormone deficiency or excess were included. We retrospectively evaluated anterior pituitary hormone levels, follow-up periods, pituitary imaging findings, symptoms associated with adenoma size increase during pregnancy, adverse pregnancy outcomes, delivery procedures, pregnancy week at delivery, birth weight, and lactation duration. RESULTS: The mean age of the patients was 41.26±9.06 years, and the mean follow-up after diagnosis was 92.8 months. Seven were diagnosed with macroadenomas (defined as the largest diameter >
10 mm) and 23 had microadenomas. There were 92 pregnancies in total. The incidence of nausea-vomiting and visual impairment during pregnancy were more common in the macroadenoma group (p=0.016 and p=0.042, respectively). Spontaneous pregnancy rates were high. The patients with NFPAs did not have an increased risk of pregnancy-related complications compared to the general population, and there were no obvious negative effects on fetal development or lactation. NFPAs were not associated with an increased cesarean section rate. CONCLUSION: These findings suggest that NFPAs, even macroadenomatous NFPAs, have no negative effects on pregnancy outcomes, fetal development, or lactation.