Purpose <p>The aim of this study is to determine the relationship between perceived stress levels and healthy lifestyle behaviors in women with high-risk pregnancy based on Neumannn Systems Model.</p> Method <p>This descriptive study was conducted between July and October 2024 with 402 pregnant women who were admitted to a public hospital in southern Turkey. The research data were collected using “Pregnancy Introduction Form,” “High-Risk Pregnancy Assessment Form,” “Perceived Stress Scale for High-Risky Pregnancies Based on the Neumannn Systems Model (PSS-HRPNSM),” and “Healthy Lifestyle Behaviors in Pregnancy Scale (HLBPS).” The research data were analyzed using independent samples t-test, ANOVA, Pearson correlation coefficient and multiple linear regression analysis.</p> Findings <p>The mean score of perceived stress levels of pregnant women with high-risk pregnancies based on the Neumann Systems Model was 83.55 ± 19.20, and the mean score for healthy lifestyle behaviors was 100.82 ± 15.84. The participants’s scores were at moderate levels in all three subdimensions of the perceived stress scale: 22.52 ± 6.25 in the physiological domain, 29.23 ± 9.54 in the psychological domain, and 31.79 ± 7.94 in the sociocultural, developmental, and spiritual domain, respectively. Significant differences were found between participants’ age, education level, and their total scores on the healthy lifestyle behaviors scale. A weak but statistically significant negative correlation (<i>r</i> = -0.158; <i>p</i> &lt; 0.001) was found between perceived stress levels and healthy lifestyle behaviors during pregnancy.</p> Conclusion <p>The study found that perceived stress levels in women with high-risk pregnancies were moderate while healthy lifestyle behaviors were at an excellent level. It was observed that as perceived stress levels decreased, healthy lifestyle behaviors improved during pregnancy.</p>