Objective: Maternal blood lipid and glucose concentrations during pregnancy affect fetal growth and the risk of pregnancy and delivery complications. We aimed to investigate the effects of physical activity (PA) during pregnancy on maternal blood lipid and hemoglobin A1c (HbA1c) concentrations. We hypothesized that higher PA was associated with improved lipid profile and glycemic control. Methods: In a secondary analysis of a randomized controlled trial, we included 216 pregnant women before week 15 + 0 and tested the effects of two different PA interventions throughout pregnancy compared to standard care on maternal blood lipid and HbA1c concentrations. Additionally, we investigated the effect of PA per se measured by an activity tracker. Total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), triglyceride, and HbA1c concentrations were measured at week ≤15 + 0, 28+0-6, 34+0-6, and at delivery (week 32 + 1 to 42 + 0). Effects of the interventions and PA per se were tested using linear mixed effects models and linear regression analyses, respectively. Results: No effects of the PA interventions were detected on maternal lipids or HbA1c during pregnancy. In PA per se analyses, more minutes per week of moderate-to-vigorous intensity PA were associated with less increase in TC (−1.3E-04, P = .020) and LDL-C (−8.5E-05, P = .035) as pregnancy progresses. More active kilocalories were associated with less increase in TC (−5.5E-05, P < .001), HDL-C (−9.5E-06, P = .024), and LDL-C (−3.2E-05, P = .005). Conclusion: Whilst there were no effects of offering PA interventions, higher PA was associated with reduced increases in TC, HDL-C, and LDL-C as pregnancy progressed.