Final answer:
The length of gestation for a baby varies among species. In humans, it is about 40 weeks or 280 days from the first day of the mother's last menstrual period. The age of the baby during gestation can be determined using the mother's last menstrual period or ultrasound scanning.
Step-by-step explanation:
The length of gestation for a baby, also known as pregnancy duration, can vary among species. In humans, the average gestation period is around 40 weeks or 280 days from the first day of the mother's last menstrual period. However, it is important to note that there is a normal range, and full-term pregnancy can be anywhere between 37 and 42 weeks.
The age of the baby during gestation is determined using various methods. In early pregnancy, the age is usually estimated based on the date of the mother's last menstrual period (LMP). This is often used as a starting point for calculating the due date. In later stages of pregnancy, ultrasound scanning can be used to measure the size of the baby and estimate the age more accurately.
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