Pregnancy Snapshot
The first week
(*Ages are referenced from time of conception or fertilization,
not from the beginning of your last menstrual period. One month equals 4 weeks.)
not from the beginning of your last menstrual period. One month equals 4 weeks.)
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Pregnancy Pictures
![See Labels []](/images/prenatal_imagegal/pregnancy/ "See Labels") Development begins with a single-cell embryo at conception!!! (Age: 0-1 day old) ![Play Movie [Fertilization]](/images/movie_grey.gif "Play Movie") ![See Labels [Two-Cell Human Embryo]](/images/prenatal_imagegal/pregnancy/0714b-th.jpg "See Labels") One cell becomes two. (30 to 36 hours old) ![See Labels [The Human Morula]](/images/prenatal_imagegal/pregnancy/0737a-th.jpg "See Labels") With 12 to 16 cells, the embryo is shaped like a tiny bunch of grapes. (3 days old) ![See Labels [Blastocyst with Inner Cell Mass]](/images/prenatal_imagegal/pregnancy/0737c-th.jpg "See Labels") The site of the future back and chest can be seen. (4 days old) The embryo begins to implant in the womb. (6 days) | |
*All prenatal ages are referenced from the time of fertilization (or conception).
One month is defined as exactly four weeks.