Compliance with the cycling intervention (as objectively measured by heart rate monitor data) was highly variable, with an average of 33% of exercise sessions completed (range 0–85%). Only a third of participants in the intervention group completed more than 30 of the 67 prescribed sessions. Notably, there was a steady decline in compliance with the exercise protocol as pregnancies progressed (Figure S2A). Total duration of cycling throughout the intervention was on average 572 minutes per participant, with 40% at low intensity, 52% at moderate intensity, and 8% at high intensity (Figure S2B).