How many days after fertilization does implantation typically occur?

Implantation typically occurs around 6 to 7 days after fertilization. This timeframe is crucial as it marks the stage when the fertilized egg, now called a blastocyst, travels down the fallopian tube and into the uterine cavity. Once it reaches the uterus, the blastocyst adheres to the uterine wall, which is critical for establishing pregnancy. This process is highly regulated and requires interactions between the endometrium and the blastocyst, ensuring that the necessary conditions are present for successful implantation.

In comparison to other timeframes presented, options indicating earlier or later implantation, such as 3-4 days or 9-10 days, are outside the typical window for this critical event. Thus, understanding that implantation occurs specifically around 6-7 days helps clarify the normal developmental timeline in early pregnancy.