Symptoms 

The symptoms may not appear until you are three weeks pregnant. Since pregnancy hormones trigger most early pregnancy symptoms, you probably do not have a very high amount of them in your body. Also, it is completely natural, so do not worry. As the weeks will progress, the number of hormones will increase. In the third week—and for the next few weeks—these are a few pregnancy symptoms you might experience:

• Implantation Bleeding: You may experience a little vaginal bleeding when the fertilized egg embeds itself into the lining of your uterus.
• Feeling Nauseous: As the pregnancy hormone HCG is released into your bloodstream and body, you may experience queasiness—or extreme nausea that will make you puke.
• Morning Sickness: If you are having morning sickness in the third week of your pregnancy, you may be further along than you think. Alternatively, you may be three weeks pregnant with twins! This is because twin moms-to-be also have higher levels of pregnancy hormones and, as a result, feel more nauseous and experience symptoms early.
• Sensitive Breasts: You will notice that your breasts will get tender and sore, and your areolas may start darkening. This is because your body will start preparing to make milk for the baby.
• Missed period. In case your cycle is shorter than 28 days, you will miss your period and probably guess that you are pregnant. One way to conform is to take a pregnancy test.
• Positive pregnancy test: Ensure that you check the box of your home pregnancy test kit to see how accurate the results are. There are many test kits in the market, which is over 99 percent correct, and some brands claim to detect pregnancy hormones in your urine much faster. (For instance, they will give you a positive result when you are three weeks five days, or even three weeks four days pregnant.)

But if you get negative, try the next day again. Here is the deal; the amount of the pregnancy hormone, i.e., HCG present in your body, might be insufficient for the test to detect it right away. But in every 48 hours, it doubles. So, if you end up getting a negative result the first time around, take another pregnancy test the next day or a few days later. And another one a week later to make sure it was not just too soon to determine.

• Positive blood pregnancy test: Since blood tests might measure lower levels of HCG than pee-on-a-stick tests, it is more accurate. A blood test can reveal that you are pregnant earlier than an at-home test. Your doctor can ask you to come into the office for a blood test in certain cases, such as if you are at the risk of a miscarriage or ectopic pregnancy.

Changes in Your Body in the Third Week

You may be pleased to see a change in your appearance. There is less chance of you showing a baby bump in the third week of pregnancy. Although you might feel bloated, most pregnant women do not have a baby bum until week 12 or later, so you still have a long way to go before you appear pregnant.

Before you start eating for two, bear in mind that most experts only suggest adding one to five pounds during the first thirteen weeks of pregnancy. As a result, you do not have permission to begin indulging at three weeks pregnant.

In general, you should not do anything more than continuing to eat a nutritious, well-balanced diet and take a regular dose of prenatal vitamins of at least 400 micrograms of folic acid. Doctors advise waiting until the second trimester to increase your daily calorie intake. Once you have completed the fourteenth week, you will want to boost your daily calorie intake by around 300 (healthy) calories.