3 Weeks Pregnant: Symptoms, Baby Development & Tips To Follow

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The 3rd-week pregnancy symptoms may seem faint or barely noticeable to some mothers. Despite that, it is one of the crucial phases of pregnancy. It is when the fetus begins to develop the neural tube, which leads to the formation of the nervous system eventually. Several precursor versions of other organ systems also form during this week, making the 3rd week of pregnancy an essential phase.

Read this post to learn the symptoms of 3rd week of pregnancy, the various developments of the fetus, and how to take care of yourself and the baby during this phase.

Changes Occurring In The 3rd Week Of Pregnancy

The following changes occur in the third week (1):

  • After being fertilized by a sperm, the female egg moves into the fallopian tube to implant itself into the uterine lining.
  • A day or two after conception, the egg (now the embryo) splits into two cells, and three days later, it splits into 16 identical cells.
  • This cell division forms a central fluid-filled cavity called the blastocoel, with the embryo now referred to as the blastocyst.
  • The blastocyst is embedded into the uterine wall and comprises the inner, outer, and middle layers. The inner layer forms the baby, and the outer layer forms the placenta, which grows and supplies food and oxygen to the growing baby.
  • Finally, the middle fluid-filled cavity will form an amniotic sac (filled with amniotic fluid) that cushions the baby throughout pregnancy.

Implantation is followed by an increase in estrogen and progesterone hormone production during this week. In addition, the hCG (human chorionic gonadotropin) hormone is also released in the blood, signaling the brain to stop ovum production.

Signs And Symptoms Of The 3rd Week Of Pregnancy

The changes in hormone levels in the early weeks of pregnancy may cause certain physiological changes. The symptoms may vary among women, with some having many signs and others having none. However, some common symptoms during early pregnancy are (2)

  • Spotting or a red or pink discharge (also called implantation bleeding), which may indicate egg implantation in the uterus. However, any severe, abnormal bleeding or pain in early pregnancy should be evaluated.
  • Nausea or vomiting due to fluctuating hormones. Severe vomiting and nausea (morning sickness) might make you dehydrated.
  • Fatigue and sleepiness
  • Tenderness in breasts
  • Food cravings or aversions
  • Heightened sense of smell
  • Bloating and constipation due to a surge in progesterone hormone, which slows down the digestion process
  • Changes in taste, such as a strange metallic taste in the mouth
  • Cramping due to implantation bleeding
  • Headaches and mood swings
  • Frequent urination
  • Slight rise in basal body temperature

These signs of pregnancy may show within a week of conception or after a few weeks in some women. Contact a healthcare provider if you notice worsening symptoms to help detect any underlying health conditions.

Pregnancy Test In The 3rd Week Of Pregnancy

If you experience any of the above pregnancy symptoms and are keen to test for pregnancy, consider waiting a week longer. Experts recommend waiting until the day you expect your menstrual period to start to get accurate pregnancy test results. This is considering the variability of ovulation timing, fertilization, and implantation in women (3).

Your Baby’s Development At Three Weeks

This week is crucial for the baby’s development. It marks the beginning of the neurulation process (central nervous system and neural tube development) and the development of the circulatory and gastrointestinal systems. Your baby may be around 0.048 millimeters (0.0019 inches) long in the third week, typically the size of a pinhead (4).

Tips For You In The 3rd Week Of Pregnancy

Here are some tips to follow to help stay healthy throughout your pregnancy (4):

  • Stay hydrated and drink lots of fluids, but avoid sodas, tea, coffee, and sugary drinks.
  • Do not strain yourself or indulge in activities that may exert pressure on your abdomen.
  • Follow a safe and regular exercise routine after consulting your physician.
  • Avoid using illicit drugs and alcohol. Consult your doctor before taking any medications.
  • Ensure you eat a well-balanced meal with sufficient protein, essential nutrients, and vitamins.
  • Refrain from smoking and excessive caffeine intake.
  • Take folic acid and calcium supplements, which are vital for you and your baby’s development.
  • Ensure to rest and get adequate sleep.
  • To combat stress, practice techniques such as listening to music and going on short walks and outings.

Nutrition Required In The 3rd Week Of Pregnancy

Proper nutrition is paramount for a healthy pregnancy. Here are some healthy foods to include in your diet:

  • Fruits and vegetables: Ensure you include all kinds of fresh fruits and vegetables (including starchy vegetables and green leafy vegetables), which are rich sources of fiber, vitamins, and minerals.
  • Protein and dairy: Add milk and milk products that are rich in calcium and protein-rich foods such as pulses, eggs, and meat to your diet.

Before planning your pregnancy, contact your doctor, who may recommend taking prenatal vitamins and supplements such as (5)

  • Folic acid: It is vital to prevent birth defects. You can also get folic acid from citrus fruits, beans, cereals, pasta, rice, and green leafy vegetables.
  • Iron: Experts state that you need twice the regular amount of iron during pregnancy. Iron supplements are prescribed in early pregnancy to avoid the risk of iron deficiency anemia during pregnancy. Include iron-rich foods such as lean meat, chicken, leafy greens, beans, and cereals.
  • Calcium: It is essential for developing your baby’s bones, teeth, heart, muscles, and nerves. Milk and its products, soya beans, green leafy vegetables, and nuts are calcium-rich foods.
  • Vitamin D: It is required for your body to absorb calcium. It also helps the body’s nerves, muscles, and immune system work properly. Besides vitamin D supplements, consume foods rich in vitamin D, such as fish, milk, and cereals.
  • DHA: It is an omega 3 fatty acid that aids in fetal growth and development, especially the eyes and brain. Seafood is rich in omega 3 fatty acids. However, consult your doctor about which fish are safe to consume.
  • Iodine: You need iodine for proper thyroid gland functioning and fetal nervous system development. Include foods rich in iodine, such as iodized salt, milk, and yogurt, in your diet.

If you are doubtful about consuming any specific foods, consult your doctor.

Frequently Asked Questions

1. What can I expect to see at a 3-week ultrasound?

Routine ultrasound is done at six to nine weeks of pregnancy. However, an early ultrasound may sometimes be recommended for other reasons. At three weeks of pregnancy, ultrasound typically shows the thickened lining of the uterus preparing for the implantation of the fertilized egg (6).

2. I am 3 weeks pregnant and constantly hungry. Is this normal?

Yes. It is normal for some women to experience constant hunger as an early pregnancy symptom (7). The changes in hormones during the early stages of pregnancy may make you hungry.

3. Does an early positive pregnancy test mean twins?

Twin pregnancy increases hCG levels (a pregnancy hormone). Since pregnancy tests detect the level of hCG in the urine, they might sometimes give an early positive result. However, this is not a confirmatory test, and further detection is needed to confirm twin pregnancy (8).

While you may not be able to confirm your pregnancy in the third week, you must take proper care, maintain a balanced diet, and take the necessary measures if you are trying to conceive. Also, ask your doctor about the prenatal supplements suitable for you. Maintaining a healthy lifestyle in this manner will help you have a safe and healthy pregnancy and delivery.

Key Pointers

  • The third week of pregnancy is marked by faint changes and barely visible developments.
  • You may experience symptoms such as spotting, hormonal fluctuation, breasts sensitivity, and frequent urination.
  • Refraining from strenuous activities, avoiding toxic habits, and staying relaxed are some of the tips to follow during pregnancy.
  • Your doctor may advise you to take specific nutrients that can help with the various developments of the fetus.


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Vidya Tadapatri

Vidya did her post-graduation in Biotechnology from Osmania University, Hyderabad. Her interest in scientific research and writing made her pursue a career in writing, in which she now has over four years of experience. She has done certified biotechnology-related training programs under renowned organizations such as Centre For Cellular & Molecular Biology and Department of Biotechnology. Vidya writes health-based articles... more

Dr. Ben Abbes Taarji Hicham

Dr. Ben Abbes Taarji Hicham is a practicing obstetrician and gynecologist with over 20 years of experience. Having worked in various Moroccan hospitals, he currently runs a private practice. Dr. Hicham specializes in rejuvenation and cosmetic gynecology, medically assisted reproduction, breast and gynecological cancers, HPV diseases, hysteroscopy and laparoscopy, and hormonal disorders.