Fertilization to implantation occurs in approximately how many days?

• A. 5-7
• B. 1-3
• C. 7-9
• D. 9-11

Answer: (A)

Fertilization to implantation occurs over about five to seven days. After fertilization in the fallopian tube, the zygote undergoes rapid cell divisions as it travels toward the uterus, becoming a morula and then a blastocyst by roughly day five or six. The blastocyst then reaches the uterine lining and begins to implant, which typically starts around day six to nine after fertilization. The most practical, exam-friendly estimate is five to seven days because it reflects both the time needed for embryonic development and the uterus to become receptive. Choices that are much shorter (1–3 days) are too early for the embryo to reach the uterus and initiate implantation, while those that push the timing later (7–9 or 9–11 days) fall outside the common teaching window.