At what age does the first trimester of pregnancy typically conclude?

The first trimester of pregnancy typically concludes at 12 weeks. This time frame is significant because it marks the end of the first stage of fetal development, during which many critical developments take place, including the formation of major organs and systems. The first trimester spans from the first day of the last menstrual period (LMP) until the end of the 12th week, making it an essential period for prenatal care.

By the end of the first trimester, many women have completed the risk of miscarriage which is more prevalent in the earlier weeks, and fetal structures have begun sufficient development, allowing for clearer sonograms and a better assessment of the pregnancy's status. This is why prenatal appointments are especially pivotal during this phase. Understanding the timeline of trimesters helps medical assistants educate patients and assist them in managing their expectations and awareness of pregnancy milestones effectively.