I also had a big baby (33 pounds at 12 months, and basically kept that weight for the next year) and built a very visible asymmetry in my left and right arm musculature over the first year or so just because of this. I am right handed, so my right hand was needed to open doors, operate locks, etc... To this day, 5 yeast later, I still have a bigger left bicep and the roll to elbow doing TGUs if much easier when I roll on the left elbow. Since I did not take advantage of the opportunity to do extra presses, my right and left presses are about equal. The specialized work of doing static holds with a bent arm caused hypertrophy and strength gains in elbow flexion and in shoulder stabilizers. All this just from holding a weight in one bent arm most days once or twice for 30 secs to 1 min! Sometimes, I had troubles with my keys or something else in the winter, and putting the little one down was not an option. A few times I got really close to muscular failure. Somehow, I always found the motivation to push harder as dropping the baby was not an option