Final answer:
The fetal stage of development begins in the ninth week after fertilization and lasts until birth. It is during this stage that the fetus undergoes significant growth and organ system development. The exact number of terminations during this period is not provided.
Step-by-step explanation:
The question relates to the fetal stage of human development, which begins at the ninth week after fertilization and continues until birth. This period marks the final stages of prenatal growth where most organs and sensory systems start to function. The actual number of conceptions that are terminated during this stage can vary widely due to a range of natural and medical factors and is not specified in the provided reference material. It is important for expecting parents to receive prenatal care to reduce health risks to themselves and to the developing baby during all stages of pregnancy, including the fetal development stage.
Fetal development progresses rapidly, and by the end of this period, the organ systems are structured and begin to function, though some may not be fully developed and functional until after birth. The fetus grows from a size of approximately 3.2 cm (1.3 in.) at the start of the ninth week to full-term at about 38 weeks following fertilization, ready for birth.