Of all the periods in the human life cycle, the period of pregnancy is the most critical and unique. It is critical because during pregnancy, the foundations of a new life is being laid that will influence the future of succeeding generations. Pregnancy has social importance affecting not only individuals but also their families and society as a whole.
Pregnancy is unique in that at no other time in life does the well-being of an individual depend so much on the well-being of another. During pregnancy, the mother and child have an intimate and inseparable relationship. The health of the mother before and during pregnancy has profound effects on the status of her infant in the womb and at birth. Therefore, efforts are directed to the mother to ensure a safe and successful delivery and that her infant will be born well.
Pregnancy or gestation is the period from conception to birth and for human beings, it lasts from 38 to 42 weeks. It is often divided into thirds or trimesters, i.e., first, second, and third trimesters. Pregnancy has three stages namely implantation, organogenesis, and growth.
Implantation is the period in which the fertilized ovum implants itself in the uterus and begins to develop. This usually occurs during the first two weeks of conception. During organogenesis, the embryo undergoes differentiation or rapid cell division that occurs from two to eight weeks after conception. This is a critical period when organs are being formed and most vulnerable to adverse influences. If cell division and the final cell number achieved in an organ are limited during the critical period, it will have irreversible effects on later developmental stage.
For example, malnutrition that occurs at this stage may affect organ development that may not be reversed by subsequent refeeding. The remaining seven months is that last stage characterized primarily by growth in the number of cells and size of the organs until it can support extra- uterine life.
Anatomic and physiologic changes accompany normal pregnancy that affects most functions of the body. Most of these changes are seen in the very early weeks showing that they are not merely a response to physiologic stress but an integral part of the maternal- fetal system to create the most favorable environment possible for the developing fetus. The changes are necessary to regulate maternal metabolism, promote fetal growth, and prepare the mother for labor, birth, and lactation.
Lactation is the period of milk production by the mammary glands. The preparation for lactation starts during adolescence when hormonal changes bring about the development and increase in size of the breast, areola, and nipple. During pregnancy, these anatomical parts are markedly increased, especially in the latter stage of pregnancy, when the lobules of the alveolar system reach maximum size.
The two main hormones responsible for milk production are prolactin and oxytocin. The first milk is a thick, yellowish fluid that comes out on the second to the fifth day after delivery. This is called the colostrums and it is very important that the baby is fed this first milk because it contains antibodies and immune cells. It is richer in protein and lower in carbohydrate and fat, compared to the breast milk in later days, which is more watery and bluish. Colostrum is also a laxative, which initially cleans out the baby’s digestive organs.
