Since earliest times the diet of pregnant women has been considered to be of great importance. It was believed that the foods eaten by the pregnant women had an influence on the physical characteristics and behavior of the unborn child. Consequently certain rigid rules as to what foods a pregnant woman should and should not eat were laid down by various societies. Even today several superstitions on this subject prevail among some people.
Pregnancy is a period of great physiological as well as psycho-logical stress for the woman. She has to maintain her health at optimum level to prepare for delivery and lactation and also to provide good nutrition for the development of the foetus. In the first trimester the rate of growth of the foetus is very slow and the mother is not able to take much food because of nausea and vomiting which are very common during this period.
It is during the next two trimesters that the foetus grows rapidly and, therefore, the nutritional needs are increased. The demand for building materials for the formation of new tissues is increased. Therefore, the diet of the pregnant woman must provide for the additional requirements. Apart from the foetal tissue which increases, the mother also grows in respect of the mammary glands and other tissues supporting the foetus. Certain other glands and tissues in the body increase in size during this period. During pregnancy a woman gains about 7 to 10 kg weight.