Top Signs of Pregnancy & Why They Happen

Top Signs of Pregnancy & Why They Happen

So you think you may be pregnant! Waiting and wondering can be hard, and you may be scrutinizing every symptom for an answer. Many of the early pregnancy signs can also have other causes, so none of them individually point to a definitive answer. Still, it’s helpful to do your homework and familiarize yourself with the top signs of pregnancy.

Estimated reading time: 7 minutes

How Early Can You Experience the Top Signs of Pregnancy?

By the time you’ve missed your period, you’ll be 4 weeks pregnant according to the traditional pregnancy calendar. The earliest pregnancy symptoms may begin is week 3 or 4 of your pregnancy — which is 1 to 2 weeks after conception.

The 40 weeks of pregnancy are counted starting from the first day of your last menstrual period, not from conception. (In other words–and as odd as it sounds–in the first couple weeks of pregnancy, you’re not even pregnant yet.) The actual date of conception can be hard to pinpoint because sperm can live for up to 5 days following sex. So, healthcare providers default to the first day of the LMP, since it’s a date you can actually track.

The First Few Weeks of Pregnancy

What’s happening in my body?

Ovulation generally occurs 14 days after the start of your last period, assuming you have an average 28-day cycle. When sperm fertilizes an egg, they together form a zygote — a single cell that begins to divide into more cells. As it divides, it moves down the fallopian tube toward the uterus.

Around 7 days after fertilization, the rapidly dividing ball of cells (now called a blastocyst) enters the uterus and burrows into the uterine lining (1). This is known as implantation. It is only after implantation occurs that the body begins produce a hormone called human chorionic gonadotropin, or hCG. This is the hormone that pregnancy tests measure, and it takes a little while for there to be enough in your blood or urine that it can be detected.

What’s the earliest I can take a pregnancy test?

So, let’s do the math. You don’t ovulate until 14 days after your period starts (or even longer if you have a longer cycle). It takes another week for the blastocyst to travel and implant. So you’re at least week 3 of your pregnancy before there is any hCG being produced. Expect at least a few more days before there’s an amount that can be detected.

This is why the very, very earliest pregnancy tests can’t detect pregnancy much before the first day of your missed period, otherwise known as week 4 of your pregnancy. 3.5 weeks pregnant is probably the very earliest you could hope for, and you should definitely not be disappointed or assume you’re not pregnant if you’re not getting positive results that early.

Top Signs of Pregnancy

Now let’s jump in and discuss the top signs of pregnancy! If you experience multiple signs, this can clue you in to whether or not you may be pregnant. But keep in mind, all of these signs can be caused by other conditions, so a positive pregnancy test is the best way to confirm.

Missed Period

An American Pregnancy Association (APA) poll showed that for 29% of women, a missed period was the first sign of pregnancy (2). In other words, a third of women have no noticeable symptoms until after they’ve missed a period.

But what happens in your body to halt your period? The hCG produced by the newly-growing placenta signals your ovaries to stop releasing eggs. In addition, it tells your body to produce more estrogen and progesterone. The increase in these hormones stops your period and starts the growth of the placenta.

Breast Changes

The same APA survey revealed that for 17% of women, breast changes were their first sign of pregnancy (2). You may notice changes in your breasts including tenderness, fullness, tingling in the nipple area, or a darkened areola. (The areola is the area around each nipple.)

Note that these symptoms are also associated with PMS. But for some women, the more extreme hormone changes that happen with pregnancy make the breast changes more pronounced.


Nausea is probably early pregnancy’s most well-known sign. For 34% of women, nausea sets in by week 4, which is right around the time you miss your period (3). For some women it comes later. Still, the vast majority of pregnant women — 94% — experience nausea by at least week 8 pregnancy. Like most of the other top signs of pregnancy, nausea is caused by changing hormones. Along with the nausea, you may have vomiting, food aversions, or food cravings.


Exhaustion is a common symptom of early pregnancy. You may feel sleepy or worn down, or it may be a fatigue unlike anything you’ve felt before. Even though you can’t see anything happening yet, your body uses a lot of energy as your baby grows! Some other things causing your fatigue may be high levels of progesterone, lower blood sugar, lower blood pressure, and a boost in blood production.

Implantation Bleeding, Cramping

Some women, although certainly not all, experience a small amount of bleeding when the embryo implants to the uterine wall. This light bleeding or spotting is normal, and may be accompanied by cramping.

Although cramping may initially feel like the arrival of your period, implantation bleeding leads to only a small amount of intermittent spotting. It’s much lighter bleeding than a regular period. You may notice a few spots of blood on a pantyliner, but you will not have to change out pads or tampons.

Bleeding Gums

You may not think of your mouth as being directly related to your pregnancy, but bleeding gums are actually pretty common. Surging hormones cause increased blood volume and increased blood flow to your gums. In some people, this makes them tender, swollen, and more likely to bleed.

Top Signs of Pregnancy: How Can I Know For Sure?

The only way to know for sure if you’re pregnant is to wait for there to be enough hCG in your blood or urine for a positive pregnancy test. If you’re really eager, you can start testing as early as three weeks after the start of your last period. But don’t be surprised if you get negative tests, and don’t assume that means you’re not pregnant. It may simply be too early to tell.

If it’s too hard to wait until you’ve missed your period, there’s no harm in repeating testing every few days. (As a side-note, the dollar store pregnancy tests won’t cut it if you haven’t missed your period yet. I can tell you from experience that they’re simply not sensitive enough to detect low amounts of hCG.) If your period is more than a week late and home tests are still showing negative, you can call your healthcare provider and ask about getting a blood test. Blood tests are more sensitive than the urine tests you can buy over the counter, and may be able to give you an answer. And if not, chat with your provider about your missed period and non-pregnancy-related causes.

Kopa Birth’s online birthing classes allow you to prepare for a natural hospital birth from the comfort of your own home, 24/7. Enroll today in our free online childbirth class and start preparing for your natural birth!


  1. The American College of Obstetricians and Gynecologists.  (2010).  Your Pregnancy and Childbirth Month to Month, 5th edition.
  2. “Pregnancy Symptoms – Early Signs of Pregnancy.” American Pregnancy Association, 24 Nov. 2018,
  3. National Collaborating Centre for Women’s and Children’s Health (UK). “Management of Common Symptoms of Pregnancy.” Antenatal Care: Routine Care for the Healthy Pregnant Woman., U.S. National Library of Medicine,
  4. Glade, B.C., Schuler, J.  (2011).  Your Pregnancy Week by Week, 7th edition.  First Da Capo Press.

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Meet Katie Griffin

I’m a registered nurse, Lamaze certified childbirth educator, and the mother of 7. I help women realize their dream of a natural, intimate, and empowering hospital birth.

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So you think you may be pregnant! Waiting and wondering can be hard, and you may be scrutinizing every symptom for an answer. Many of the early pregnancy signs can