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 tubeⁱA hollow structure in a developing embryo that forms the brain and spinal cord. , 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 the 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 tubeⁱA hollow tube-like structure that connects ovaries to the uterus and forms a channel for the eggs to pass. 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 placentaⁱA temporary organ that connects the baby to the uterus and provides oxygen and nutrients to it. , 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 fluidⁱClear, yellowish fluid surrounding the fetus in the uterus and provides protection and nutrients to the growing baby. ) that cushions the baby throughout pregnancy.

Implantation is followed by an increase in estrogenⁱA sex hormone responsible for the development of female sexual characteristics. and progesterone hormone production during this week.

In addition, the hCG (human chorionic gonadotropinⁱA hormone produced by the placenta that helps thicken the uterine lining for fetal development. ) hormone is also released in the blood, signaling the brain to stop ovum production.

Quick fact

Pregnancy days are determined from the first day of the last menstrual period; hence, the third week corresponds with implantation (4).

Signs And Symptoms Of The 3rd Week Of Pregnancy

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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
• Breast tenderness
• Food cravings or aversions
• Heightened sense of smell
• Bloating and constipation due to a surge in progesteroneⁱA female reproductive hormone that plays an important role in menstruation, pregnancy, and breastfeeding. hormone, which slows down the digestion process
• Heartburn
• Changes in taste, such as a strange metallic taste in the mouth
• Cramping due to implantation bleeding
• Headaches, dizziness, and mood swings
• Increased 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.

Chelsie Remund, a mother of one, shares how she learned about her pregnancy when she was three weeks pregnant. She writes, “I hadn’t missed my period; however, I know my body enough to know something was DEFINITELY different… The symptoms I normally have when my period is approaching were fairly similar, so I wasn’t too nervous at this point. The only reason pregnancy was a thought at this time was because I had extremely sore breasts and extreme fatigue. Oh! And let’s not forget the raging hormones!” Later, she took a pregnancy test, which came out positive (i).

Pregnancy Test In The 3rd Week Of Pregnancy

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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).

Point to consider

Blood pregnancy tests can detect a pregnancy before a urine test. You may get the result at around seven to twelve days from conception (9).

Your Baby’s Development At Three Weeks

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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

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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.

Quick tip

Mindfulness practices and prenatal yoga helps relieve stress and support physical and mental well-being (10).

Nutrition Required In The 3rd Week Of Pregnancy

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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. It’s important to note that anemia affects around 37% of pregnant women, according to the World Health Organization (WHO). To boost iron levels naturally, incorporating iron-rich foods into the diet is essential. Some examples include 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.

Infographic: Dietary Needs Of A Three Week Pregnant Woman

At three weeks of pregnancy, your baby is in the significant stages of development. So, during this stage, you should eat a healthy and nutritious diet to meet all the nutritional requirements for the baby and you. The following infographic includes major food items you must include in your pregnancy diet to get adequate nutrition.

Illustration: Momjunction Design Team

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

Image: Stable Diffusion/MomJunction Design Team

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Reviewer Author Editor Fact Checker

Dr. Ben Abbes Taarji HichamMD

Dr. Ben Abbes Taarji Hicham is a practicing obstetrician and gynecologist with around 20 years of experience in the field. 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.

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Vidya TadapatriMSc (Biotechnology)

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 five 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.

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Rebecca MalachiBSc

Rebecca is a pregnancy writer and editor with a passion for delivering research-based and engaging content in areas of fertility, pregnancy, birth, and post-pregnancy. She did her graduation in Biotechnology and Genetics from Loyola Academy, Osmania University and obtained a certification in ‘Nutrition and Lifestyle in Pregnancy’ from Ludwig Maximilian University of Munich (LMU).

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Aneesha AmonzMSc

Aneesha holds a Bachelor's degree in Biotechnology from USTM, Meghalaya and Master’s degree in Applied Microbiology from VIT, Vellore. With two years of experience, she has worked on different research projects in the field of Food Sciences.

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