BackgroundWomen usually decrease their physical activity (PA) after becoming pregnant. The change in PA may influence their symptom distress (SD). The changes and correlations between SD and PA throughout pregnancy remain unclear.AimsThe aims of this study were to describe PA and SD trajectories across all three trimesters and examine their correlations during pregnancy.MethodsA repeated‐measure longitudinal study with convenience sampling at a hospital in Northern Taiwan was performed. Participants were recruited at 8–16 weeks of gestation, and two follow‐up visits were performed at 24–28 weeks of gestation (second trimester) and after 36 weeks of gestation (third trimester). A total of 225 participants completed the study. The participants completed the Pregnancy Physical Activity Questionnaire (PPAQ) and Pregnancy‐related Symptom Disturbance Scale (PSD), and sociodemographic and prenatal variables were recorded.ResultsThroughout pregnancy, SD decreased then increased, showing an overall upward trend, whereas PA showed the opposite pattern, increasing then decreasing, with an overall downward trend. Sedentary activity was positively correlated with both physical and psychological SD during the second and third trimesters. Exceeding the Institute of Medicine's recommendations for gestational weight gain, having childcare support, sport/exercise‐type, and light‐intensity PA were negatively associated with the physical and psychological SD, while a history of miscarriage and sedentary‐intensity PA were positively associated with the physical and psychological SD.Linking Evidence to ActionWhile several factors, including light‐intensity PA, were found negatively associated with the physical and psychological SD, sedentary‐intensity PA were positively associated with the physical and psychological SD, our findings shed light on future intervention strategies to relieve SD and decrease sedentary behavior among pregnant women.