• Embryo Dividing
    Week 3 of Pregnancy
    You are 2 Weeks and 4 Days Pregnant
    What's happening insideThis is an embryo at the 16-cell stage, when it has changed from a zygote into a morula. It is in the process of dividing into a hollow ball of cells-the blastocyst-which will eventually implant in the lining of the uterus....
  • blastocyst hatching from its shell
    Week 3 of Pregnancy
    You are 2 Weeks and 5 Days Pregnant
    What's happening insideThis is an embryo at the blastocyst stage, five days after fertilization. It is seen hatching from the shell that originally surrounded the unfertilized egg. At this stage, the blastocyst has moved into the uterus and is pr...
  • blastocyst resting on the lining of the uterus
    Week 3 of Pregnancy
    You are 2 Weeks and 6 Days Pregnant
    What's happening insideThe blastocyst prepares to embed itself in the lining of the uterus-the endometrium. Once it is completely implanted-usually around seven days after fertilization-the pregnancy will become established. ...
  • human egg surrounded by sperm
    Week 3 of Pregnancy
    You are: 2 Weeks and 1 Day
    What's happening insideHere the egg is shown surrounded by sperm. Although only one sperm will fertilize the egg, several hundred are thought to be necessary to break down its defensive layers and enable fertilization to take place. ...
  • 24 hours after conception
    Week 3 of Pregnancy
    You are 2 Weeks and 2 Days Pregnant
    What's happening insideHere is a diagram of a human egg cell 24 hours after fertilization. Around the egg is a thick layer (yellow) that has now become impenetrable. The circles inside, or pro-nuclei, contain genetic material from the mother and ...