TTC Articles

Pregnancy Calendar Guide: Week-by-Week
Luteal Phase, Implantation, and When to Test for Pregnancy

> TTC Weeks 1 and 2: From Menstruation to Ovulation
> TTC Week 3: From Ovulation to Conception
> Week 4: Implantation and the Luteal Phase
> Pregnancy Week 1: Early Pregnancy Symptoms & Fetal Development
> Pregnancy Week 2: What to Expect During Your First Trimester
> Pregnancy Calendar Home

In Part 1 of our discussion, we looked at how your body prepares for ovulation and pregnancy - the build-up of the endometrium and the development of the ovarian follicle. In Part 2, we observed ovulation and followed the egg down the fallopian tube where fertilization/conception took place. Now we are on the fourth week of your cycle - in the middle of the luteal phase - and things are heating up (quite literally). Let's see why...

The luteal phase of your menstrual cycle comprise the cycle days following ovulation. This two-week period is called the luteal phase because of the dominant role played by the corpus luteum, which is nothing other than the collapsed follicle from which the egg issued forth. Now, it's the job of the corpus luteum to pump out the hormone progesterone and "heat up" the body and womb in preparation for pregnancy.

Progesterone also helps the endometrium thicken and become more vascular, and in this way the endometrial lining becomes like a "soft pillow" to catch the descending blastocyst (fertilized egg). Last and certainly not least, progesterone sends a signal to your brain to not commence with menstruation, the shedding of the uterine lining known as your period. As we shall see, the developing embryo has its own hormonal signal that will tell the body "I'm here!" in order to forestall menstruation by telling the body to keep making progesterone. When this hormone, hCG, shows up, you can detect it with a pregnancy test and discover that this was the lucky month!

The Body and The Luteal Phase: With progesterone high, women may experience tender breasts and nipples. Confoundingly, this is also an early pregnancy symptom as well. If you are fertility charting and you know where you are during your cycle, you can dismiss this early tenderness as a possible effect of post-ovulation progesterone. However, if tenderness continues or intensifies when you normally do not experience this sensitivity, you may have an early pregnancy sign. Progesterone can also precipitate PMS-symptoms like irritability, moodiness, etc.

After ovulation takes place, your cervical mucus will also undergo changes. Likely, the amount of mucus will decrease (some women experience dryness here) or the color/texture will change from transparent-stretchy to a white or yellow shade that is a bit more sticky and firm. Of course, women may experience different types of CM after ovulation and throughout the first part of the luteal phase. If you suspect you may have issues relating to CM, a product called FertileCM can help to improve the quantity and quality of cervical mucus you produce.

In Part 2, we last saw the egg undergoing certain changes following fertilization (i.e., differentiation, becoming-blastocyst). The zona pellucida that once protected the incipient embryo now becomes redundant and the blastocyst produces an agent to dissolve this protective shield. At this point, the blastocyst escapes from the zona pellucida and becomes a free-floating body within the womb.

We're now nearly a full week after ovulation and conception. Progesterone levels are high and embryo is ready to "hook up" with the mother-to-be. If all goes well, the embryo will now land within the endometrium and connect to the wall of the uterus. This process is called implantation and is formerly the first moment of pregnancy, when the blastocyst technically becomes the embryo.

Implantation: During the process of implantation, cells on the surface of the blastocyst make contact with the endometrial lining and begin to chemically "open up" a space within the lining where the fertilized egg may fasten. As a fold or region in the endometrium is produced, the blastocyst (now embryo) nestles itself within the uterine lining. This event may cause some tell-tale signs - and potentially the very first symptom of pregnancy, implantation bleeding. Implantation bleeding is simply defined as light spotting that may appear during the implantation process. The color of the blood will not be red, as with your period, but typically a pinkish or brownish shade. Not all women will experience this spotting - in fact, most do not - so if you do not observe implantation bleeding, this does not at all delimit the possibility of pregnancy. So now we have an embryo and, ta-da, pregnancy has just been achieved!

When Can I Take a Pregnancy Test?!? The question we have all been waiting for! At this point, breast tenderness may be attributable to naturally-occuring amounts of progesterone independent of pregnancy. Implantation spotting, while possible, is by no means a necessary sign. So now we wait for the day we can commence with pregnancy testing. As implantation typically occurs between six and ten days after you ovulate - and pregnancy testing should not officially begin before implantation - deploying pregnancy tests during the week following ovulation is generally a simple waste of money. But before we begin with when we can test, let's look at how pregnancy tests work in relation to what is going on with the embryo and your body...

Following implantation, the embryo continues to burrow into the endometrium and its fertile matrix of vascular-rich tissue. At this stage, the embryo casts a membrane around itself called the chorion, which is the inner layer of the developing placenta. The chorion's job is to establish a connection between the life-sustaining womb and the embryo, tapping into blood vessels in the endometrium that will nourish the fetus during your 9 months of pregnancy. Once this critical link is made, the placenta will begin to form around the chorion and embryo, the intermediary zone between mother and fetus where nutrients are ushered in and waste products removed. With the nascent placenta, the bubble-like amnion forms around embryo to shield and nourish the fetus during pregnancy, sustaining the fetus in protective amniotic fluids that both prevent the dehydration of fetal tissues and relieve any potential damaging pressure from within the womb.

With the development of placental tissues, the fetus is ready to tell mom to go ahead and not have her period - in effect, to "shut down" the menstrual cycle. This important message is, like all previous bodily communiques, conducted via hormonal signals and triggers. In this case, the placenta issues forth an agent call hCG, or Human Chorionic Gonadotropin, and if you have already read the description from our product description page, then you know that this is the hormone detected by our pregnancy tests. So, hCG is now flowing through your system and emphatically encouraging your corpus luteum to keep pumping out the progesterone - in turn preventing menstruation. This is why you experience your "missed period", another fundamental pregnancy symptom. We also attribute morning sickness to this hormone as well.

So, after this long exegesis on hCG, we're still at a week after ovulation or so. We now understand that the "Chorion" in Human Chorionic Gonadotropin is related to the formation of the placenta. hCG is now flooding through your body, and the amount of hCG increases rapidly during the first weeks of pregnancy, doubling nearly daily. At seven to ten days past ovulation, you can begin testing for pregnancy with higher sensitivity pregnancy tests. Early detection pregnancy tests are excellent, though if you do receive a negative result this early, this should not be interpreted conclusively that pregnancy was not achieved. hCG can increase at different speeds, so we do urge you to test again using first morning urine samples. If you only have a few of our tests, we suggest taking the first one at ten days past ovulation and the second test a week later. What's nice about our very affordable test strips is that you can test practically daily!

We'll pick an arbitrary day - how about 10 DPO , or ten days past ovulation? You just awoke and tested with a first morning urine. The control line materializes almost immediately and slowly but surely you see a test line hovering at the threshold of perception. Three minutes pass and you see your first test color band, albeit somewhat faint. At five minutes, the complete reaction time of the test, it's clearly there - a faint but distinct color band in the test region of the strip! As hCG develops in your body, this test line should deepen and become bolder over the following days with consecutive follow up tests.

Next... Pregnancy Week 1: Early Pregnancy Symptoms & Fetal Development

See Also:
> Pregnancy Week 2: What to Expect During Your First Trimester
> Pregnancy Calendar Home