Your baby this week
3 weeks pregnant

In the know

The fertilized egg is now a blastocyst -- a hollow sphere with two different types of cells and a central cavity. The surface cells (trophectoderm) will become the placenta, while the inner cells, called (the inner cell mass) will become the embryo.


Today or tomorrow (or therabouts), the blastocyst will implant itself in the endometrium, the blood-rich mucus membrane lining the uterus, which is usually shed as your period.

Are you curious about what needs to take place in order for implantation to be successful? Researchers have discovered how an embryo initially attaches to the wall of the uterus -- what appears to be one of the earliest steps needed to establish a successful pregnancy. Specifically, the researchers found that six days after an egg is fertilized, the embryo uses specialized molecules on its surface and molecules on the surface of the uterus to attach itself to the wall of the uterus.

About six days after fertilization, the embryo is shaped like a sphere. The surface of the sphere is made up of a layer of specialized cells called the trophoblast, and at this phase of development, the embryo is called the blastocyst. The trophoblast later gives rise to the cells that will form the fetus' part of the placenta, which is made up of both maternal and fetal tissues.)

Want an easy way to explain this to your friends at your next girls' night out? Think about a tennis ball rolling along a table top covered in maple syrup! To learn more, click right here.

Feeling different?

Are you already feeling pregnant? This may be a result of the progesterone that is secreted by the corpus luteum.

What is the corpus luteum, you ask? It is a structure that develops in the ovary and secretes progesterone, which is vital to maintain a uterine environment capable of supporting pregnancy. When the corpus luteum stops functioning, and if a fertilized ovum does not embed in the uterine lining and the placenta begins producing hormones of its own, hormone levels quickly decrease and menstruation begins.

Progesterone can cause a wide variety of symptoms, from aching breasts to bloating to feeling a bit hormonal. In other words, progesterone is usually the culprit behind our lovely friend PMS... and PMS symptoms can mimic pregnancy! When you are trying to get pregnant you tend to be more aware and sensitive as well. Aren't hormones fun?

OTC does not mean "safe"

You might consider ibuprofen or acetaminophen to be safe (after all, aren't they common in our medicine cabinets?), but keep in mind that in 2007, the British Medical Journal published a study showing the increased risk of miscarriages in women who used non-steroidal anti-inflammatory drugs (NSAIDs) -- a category of medication that just happens to include ibuprofen and acetaminophen. For some easy (and hopefully helpful!) non-drug treatments during pregnancy, check out this article.


Ovaries are the sexual glands of the female. They produce the hormones estrogen and progesterone, and both create and house your eggs! There are two ovaries -- one on each side of the pelvis -- and they are connected to the uterus by the fallopian tubes.

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