During the two weeks following fertilization, the zygote divides into many cells, and these cells sort themselves into three layers. Minimal growth in size takes place at this time, however, there is a lot of cell division. This is a critical period developmentally. Adverse influences such as smoking, drug abuse, and malnutrition at this time lead to failure to implant or to abnormalities that can cause loss of the zygote, possibly even before the woman knows she is pregnant. Both mother and child will benefit most from an optimal supply of nutrients uncontaminated by other material.
Pregnancy affects maternal tissues through the many hormones synthesized to support the pregnancy.
These hormones are necessary for the pregnancy to be successful. Progesterone induces fat deposition which aids in insulation of the baby and provides energy reserves. Progesterone also relaxes smooth muscle which will cause a decrease in intestinal motility resulting in increase nutrient absorption. Estrogen production increases tremendously during pregnancy and is important for growth promotion, uterine function and water retention. Nutrition and Pregnancy 475 Pregnancy increases nutritional requirements.