Final answer:
During the first trimester of pregnancy, major organ systems form. The second trimester sees growth, movement, and sensory development, while the third trimester involves further growth and maturation. Development can be affected by nutrition, substance exposure, environmental pollutants, infections, and stress.
Step-by-step explanation:
Major Milestones of Fetal Development During Pregnancy
Pregnancy is typically divided into three trimesters, each with its distinct milestones in fetal development. In the first trimester, crucial structures and organ systems begin to form; this includes the brain, spinal cord, heart, and limbs. The embryo transitions into a fetus, with facial features beginning to emerge.
In the second trimester, the fetus grows significantly, begins to move actively, and can start to hear. Fingernails, toenails, and real hair start to develop. The sex of the fetus can usually be identified during this period.
The third trimester is marked by further growth and maturation of systems; the fetus gains weight, senses mature, and the lungs prepare for breathing.
Dietary and Environmental Factors Affecting Development
- Nutrition: A diet rich in essential nutrients, especially folic acid, is crucial for preventing birth defects.
- Substance exposure: Tobacco, alcohol, drugs, and certain medications can cause developmental problems or birth defects.
- Environmental pollutants: Exposure to certain chemicals and pollutants can negatively impact fetal development.
- Infections: Certain infections during pregnancy can lead to complications and affect fetal development.
- Stress: High levels of maternal stress can impact the health of the fetus.