Background: Physiological changes during pregnancy are often accompanied by reduced sleep quality, sleep disruptions, and insomnia. Studies conducted among men and non-pregnant women have documented psychiatric disorders as common comorbidities of insomnia and other sleep disorders. However, no previous study has examined the association between stress-related sleep disturbances and psychiatric disorders among pregnant women. Methods: This cross-sectional study included a total of 2051 pregnant women in Peru. The Spanish-language version of the Ford Insomnia Response to Stress Test (FIRST-S) was used to assess sleep disruptions due to stressful situations. Symptoms of antepartum depression, generalized anxiety disorder, and posttraumatic stress disorder (PTSD) were examined using the Patient Health Questionnaire-9, Generalized Anxiety Disorder Scale-7 and PTSD Checklist – Civilian Version, respectively. High risk for psychosis was assessed using the Prodromal Questionnaire. Multivariable logistic regression procedures were used to estimate adjusted odds ratios (ORs) and 95% confidence intervals (CI). Results: Stress-related sleep disturbance was reported by 33.2% of women. Of all women, 24.9% had antepartum depression, 32.2% had generalized anxiety disorder, 30.9% had PTSD, and 27.6% were assessed as having a high risk of psychosis. After adjusting for confounders, women with stress-related sleep disturbances were more likely to experience antepartum depression (OR = 2.74; 95%CI: 2.22–3.38), generalized anxiety disorder (OR = 2.48; 95%CI: 2.04–3.02), PTSD (OR = 2.36; 95%CI: 1.93–2.88), and high risk for psychosis (OR = 2.07; 95%CI: 1.69–2.54) as compared to women without stress-related sleep disturbances. Conclusions: Stress-related sleep disturbances during pregnancy are associated with increased odds of psychiatric disorders. Inquiring about stress related sleep disturbances during antenatal care may be beneficial for identifying and caring for women at high risk of psychiatric disorders.