Gestation Period:
Gestation period refers to the time from conception to birth during which a developing fetus grows and develops inside the mother's womb. It varies in duration across different animal species, including humans.

Gestation Period in Humans:
In humans, the gestation period is approximately 9 months or 280 days. This period is divided into three trimesters, each lasting about three months.

First Trimester:
- The first trimester spans from the fertilization of the egg by sperm until the end of week 12.
- During this time, the fertilized egg implants itself into the wall of the uterus and begins to develop into an embryo.
- The major organs and structures of the body start to form, and the heartbeat can be detected.

Second Trimester:
- The second trimester begins at week 13 and lasts until week 27.
- By this stage, the developing fetus is about 3.5 inches long and weighs around 1.5 ounces.
- The organs continue to mature, and the fetus starts to move and respond to external stimuli.
- The mother may also begin to feel the baby's movements during this period.

Third Trimester:
- The third trimester starts at week 28 and continues until birth.
- The fetus undergoes rapid growth, gaining weight and developing more body fat.
- The organs and systems become fully functional, and the baby's position in the womb changes in preparation for birth.
- Towards the end of the third trimester, the mother may experience Braxton Hicks contractions, which are practice contractions that help prepare the uterus for labor.

Conclusion:
The gestation period in humans lasts approximately 9 months or 280 days. It is divided into three trimesters, each characterized by specific developmental milestones. Understanding the gestation period is crucial for monitoring the health and progress of pregnancy and ensuring the well-being of both the mother and the baby.