Stages of Pregnancy

Human pregnancies are divided into three stages, known as trimesters. Lasting a total of approximately 40 weeks, each stage is distinct and involves different types of growth or development for the woman and her fetus or embryo.

First trimester

The first trimester begins approximately two weeks before the woman is pregnant and concludes around 13 weeks, or 3 months. This is when the growing embryo undergoes its greatest development. It never grows or develops as fast in the rest of the pregnancy. Advancing from a two-celled organism, it eventually develops two arms and legs, a beating heart, visible and distinct human facial features and the beginnings of the vestigial sex organs. Many women report feeling extremely tired and fatigued, nauseous and anxious about their pregnancies, as the majority of miscarriages occur during this time.

Second trimester

The developing fetus, Latin for little one, grows longer and picks up some weight during this stage. First moments are felt at times, although kicks grow stronger in the third. Women often feel strong, with a voracious appetite. Some consider this the healthiest they have ever felt. More weight is picked up by the pregnant woman, and she starts to show.

Third trimester

The fetus begins preparations for birth. Changes to the breasts, that started during the first trimester, allow the woman to nurse her newborn child. She picks up a waddling gait, as her fetus picks a head-down position in her pelvis. Ligaments in her pelvis loosen, allowing her birth to progress easier. The fetus picks up the majority of its weight during this stage. The average baby at birth weighs between 6 and 7 pounds and is 18 to 20 inches long.

The human fetus goes through many changes in its three trimesters of pregnancy. Learning these stages makes pregnancy less confusing and more joyous for the new mother.