Final answer:
The normal term of pregnancy is 280 days or about 40 weeks, starting from the first day of the last menstrual period. This gestation period is divided into three trimesters, each with specific developmental milestones and maternal changes.
Step-by-step explanation:
The normal term of pregnancy is 280 days. This period, which is approximately 40 weeks, is commonly calculated from the first day of the last menstrual period (LMP) rather than the exact date of conception, assuming conception occurred around day 14 of the menstrual cycle.
Throughout a pregnancy, various changes occur during each of the three trimesters, which are each about 13 weeks long. Notable developments include the dramatic growth of the pre-pregnancy uterus to accommodate the developing fetus, changes in maternal nutritional needs, and stages of embryo and fetal development. A full-term pregnancy is usually defined as one that lasts from 37 to 42 weeks, with the average gestation period for humans being around 266 days when counted from the time of fertilization.
Pregnancy length may slightly vary from one individual to another, but typically, a full-term pregnancy falls within these parameters to ensure a healthy development and birth process. Pregnancy milestones like the detection of fetal movements, increases in nutritional intake, and prenatal care are essential for monitoring the health and development of both the mother and fetus during this critical period.