Infant carrying has been reported to be physically demanding with risks of physical challenges to mothers/caregivers. This makes it important to evaluate different Infant Carrying Methods (ICMs) to guide choices for the promotion of maternal health. This study evaluated the effects of four ICMs (A–back, B–front, C–side, and D-in-arms) on trunk muscular activities. Thirty women simulated four ICMs while the electrical activities of the right (Rt) and left (Lt) components of the erector spinae (ES), rectus abdominis (RA), and external oblique (EO) muscles were recorded simultaneously during the tasks. Within-subject comparisons of the muscle activities showed that only the front (p = 0.011) and side (p = 0.033) ICMs elicited significant differences with their highest activities recorded in the left and right EO muscles, respectively. Between-subject comparisons of the muscle activities showed a significant difference (p = 0.022) only in the right EO muscle, being most active during the side ICM. The side ICM was observed to elicit the highest activities in three of the four studied muscles. Side ICM has more potential for over-exerting the trunk muscles, which could be a possible factor for muscular fatigue and resultant musculoskeletal impairments.