4 Weeks After Conception

Now having been in existence for a month (since conception), your little one is about 1/6 of an inch long and has a head and a trunk. Limb buds -- early arms and legs -- are starting to be apparent.
A little baby face starts to take shape now: There are the beginnings of a mouth, and little divots that will become the ears and eyes begin to form.

No longer a flat disk, the sides of the embryo begin to fold along the long axis (a.k.a. the primitive groove or streak) and is three dimensional. The chest and stomach are forming, and the heart -- right now just a little tube -- starts beating around the 22nd to 25th day after conception. That wee heartbeat will be visible via ultrasound soon! Similarly, your baby's brain waves can now be measured with an electroencephalogram.

Here's a closer look at what your baby may look like right around four weeks after conception, or at six weeks menstrual age.

Week 6

See some ultrasounds from week six of pregnancy:
  • Early pregnancy
  • 6 weeks, 4 days
  • 6 weeks, 5 days
  • Read a few articles about what you might expect during your first trimester: See them here
    Check out what some real moms had to say about their first trimester: Click to take a peek
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    See other weeks here:

    Week 2 Week 4 Week 8
    Week 10 Week 12 Week 16
    Week 20 Week 24 Week 28
    Week 32 Week 36 Week 40

    Note: These images and information are not meant to convey precise detail, but rather the general shape and progression of your baby as he or she develops. These drawings are not to scale, and are for educational purposes only. Every baby is different, and this information should not be construed as medical diagnosis or advice.

    For more on your baby's development and changes in your body, be sure to check out our day-by-day pregnancy calendar! PregnancyAndBaby.com

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