Pregnancy is a physical condition that brings with it profound changes to the function of the female body. The growth of another living being within the uterus creates a remarkable organic partnership between the mother and the developing fetus. The maintenance of physical health in the mother, both through adherence to strong dietary and nutritional practices, as well as through exercise consistent with the physical changes brought by pregnancy, are the most important factors in the corresponding healthy development of the unborn child.
Pregnancy begins the moment that the female ovum (egg cell) has been fertilized by a male sperm cell; this fertilization is the act of conception. The cell division that propels the growth of the embryonic fetus begins approximately 30 hours after conception. The cell division and growth continue from the embryonic stage until the fetus (as the unborn child is often referred from the fourth month of pregnancy until birth) is delivered into the world as a newborn infant. From the moment that cell division begins, any environmental impacts on the mother, such as exercise activities, will impact how the fetus will develop within the uterus.
In many cultures throughout the history of the world, pregnant women were expected to carry on with their daily chores in both the home and the community. Any physical work that was usually required of women continued through their pregnancy, almost until the moment that birth was imminent. Many industrialized societies adopted a different view of the capacities of pregnant women in the later 1800s; in the middle classes of England and North America, it was common for pregnant women to be virtually confined to their homes for the duration of the pregnancy, with pregnancy regarded with the same precautions as would have been taken with an illness.
Modern medical science clearly endorses the proposition that both the health and the overall well-being of both mother and unborn child is enhanced by exercise, so long as the physical activity is proportionate to the physical condition of the mother. The general benefits gained by a pregnant woman through a structured exercise program include:
Exercise places energy and overall nutritional demands on the body, as does the growing fetus; by the fifth week of pregnancy, the embryonic fetus has its own heartbeat and it is receiving nutrition directly through the wall of the uterus. As the fetus grows, its own nutritional demands on the mother's reserves of
The exercise selected by the mother must be comprised of activities that avoid any significant physical risk. Sports where a fall is possible are important to avoid, especially as the female center of gravity while pregnant will affect normal balance. The generation of or exposure to excessive heat is also dangerous for both mother and fetus, as activities that cause dehydration will often trigger such dangerous conditions as lower blood volumes. A pregnant woman's resting pulse is elevated from her normal resting rate, which creates a further reason to avoid excess heat.
As a general rule, the more stable the body of the pregnant woman during exercise, the better the activity. Due to the hormonal changes that occur during pregnancy, ligaments and other connective tissues become softer and more prone to joint injury if the tissue absorbs a trauma or if it is subjected to overstretching. The additional weight gained as the pregnancy progresses also can impact joint health.
The intensity and the volume of the exercise undertaken by a pregnant woman can be moderated to suit her personal medical circumstances and her previous level of fitness. Activities such as walking, yoga, Pilates, and stationary cycling are generally safe. Swimming and a variant of aerobic exercise, aquarobics, are both excellent exercises for pregnant women.