Life Stage

The prenatal stage, and hence the beginning of a person's life cycle, begins with conception. Conception is the moment when a sperm fertilizes an egg to create a single cell called a zygote. The zygote will undergo a period of cell division forming a blastocyst (a ball-shaped collection of cells) that implants itself in the uterine wall. After the blastocyst begins to develop rudimentary organs, it is an embryo. Around the eight-week mark, the organs have finished developing, and an embryo is considered a fetus. The fetal period is marked by the development of placenta and organ maturation. The prenatal stage ends at childbirth, approximately 38 weeks after conception. A full-term pregnancy lasts 38 to 42 weeks and is divided into three trimesters, with each trimester lasting about 13 to 14 weeks.

Adopting a healthful diet prior to conception includes the avoidance of alcohol, illegal drugs, and other known teratogens (substances that cause birth defects). Women should also consult their healthcare provider about their consumption of caffeine, medications, herbs, and supplements, and if they smoke, they should attempt to quit. A balanced, nourishing diet is important throughout pregnancy to provide the nutrients needed to support fetal development without depriving the mother of nutrients she needs to maintain her own health. It also minimizes the risk of excess energy intake.

During pregnancy, protein needs increase to 1.1 g/day/kg body weight (an additional 25 g or so of protein per day). Many women already eat this much protein each day. Dairy products, meats, eggs, and soy products are all rich sources of protein, as are legumes, nuts, and seeds.

Carbohydrate intake should be at least 175 g/day. The majority of carbohydrate intake should come from whole-grain breads and cereals, brown rice, fruits, vegetables, and legumes. Not only are these carbohydrate-rich foods good sources of the B vitamins and other nutrients, but they also contain a lot of...