On the basis of the understanding of the cellular mechanisms of thyroid hormone action on the heart and cardiovascular system, it is possible to explain the changes in cardiac output, cardiac contractility, blood pressure, vascular resistance, and rhythm disturbances that result from thyroid dysfunction.
Last updated: July 2015. Tummy time is essential from day one to help your baby grow strong â even if your baby fusses and cries when you put him on his belly. Experts find that babies who don't spend time face-down often have some delays in their development of motor skills.
If youâre just introducing tummy-time play, begin with a few minutes at a time, allowing your baby to get used to the new position. Some parents start tummy-time play for about a minute or so at 1 or 2 months of age, when babies can hold their heads up for a short time. Others wait until a child is 3 or 4 months old, when the neck, shoulder and torso muscles are stronger.