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Pregnancy Week 4 Symptoms: Fourth Week Symptoms and Early Signs of Pregnancy Before Missing Period


It is time for implantation at week four of pregnancy. The embryo or the mass of cells attaches to the sticky uterine lining and connects with the mother for support and nourishment for the next eight-plus months.

While the baby is tiny as the size of a poppy begins its growth with the mass of cells demarcating itself to form the building blocks of vital organs. The mother can officially confirm her pregnancy with the placenta releasing detectable amounts of hCG, checked during the pregnancy test.


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4 weeks pregnant is how many months of pregnancy?

Four weeks pregnant means that you are in the first month of pregnancy, and you have only eight more months to go to meet your little one. 

Now, let us understand what more you can expect in week 4 of pregnancy.

Baby @ Week 4 of Pregnancy

When you reach week 4 of pregnancy, the embryo in its blastocyst stage finds a home in the uterine wall developing a communication channel for nutrient supply and waste elimination for the next eight months of development. The embryonic sac and the yolk sac are also formed, giving the developing womb a perfect insulating and nourishing environment for the developing embryo. 

How big is the baby at week 4?

As the blastocyst houses itself in the uterus, it develops into a distinct cell stage. The size of the young embryo is as tiny as a poppy seed, just above 1 mm.  

Embryo growth and formation of the placenta

It’s week four, and the blastocyst must have completed its voyage from the fallopian tubules to the uterus. Once it reaches the uterus, the mass of cells gets buried under the thick uterine walls – marking the commencement of an unbreakable bond between the mother and the baby.

As the embryo connects to the mother, the little ball of cells undergo great division. Half of the cells aid fetal development, and the other half cells form the placenta – a lifeline for the baby channeling nutrients and eliminating waste until birth. 

Foundation for vital organ development

Surrounding the cellular mass develops the amniotic sac or the water bag- a cushion to protect the developing fetus. The yolk sac, nourishment provider, also emerges even before the placenta, forming the source of nourishment for the young embryo.

At this stage, the embryonic cells categorize into three definitive layers that will eventually develop into essential organs.

  • The inner layer or endoderm will soon develop into the baby’s digestive organs such as liver, intestines, stomach, etc.
  • The middle layer of cells or mesoderm is ready to form the baby’s heart, kidneys, lungs, and reproductive organs. 
  • The outer layer or ectoderm, in due time course, develops into the baby’s nervous system, hair, eyes, and skin. 

It is incredible to know, by week 4, the neural tube – the elementary unit for the spine, brain, and backbone is in place with the foundation cells of other organs affirming themselves. 

Does my baby have a heartbeat at week 4 of pregnancy?

At week 4 of pregnancy, the tiny embryo is yet to have a heartbeat. The cells developing the heart and circulatory system are firmly distinguished, but these organs will eventually develop in the coming weeks of pregnancy and the heartbeat. 

To-be Mom @ Week 4 of Pregnancy

Noticeable pregnancy symptoms get into action by week 4. Here, the embryo implantation has just occurred, and the embryo attachment brings about hormonal changes with a basket of symptoms. The placenta development secretes surplus quantities of human chorionic gonadotropin (hCG) good enough to be detected in a home pregnancy test kit. However, if you cannot conclude pregnancy through a home pregnancy test kit, an appointment with your doctor for a blood test can do the needful. Here is a sneak peek into the pregnancy symptoms you observe during week 4 of pregnancy. Nonetheless, it is normal if you experience none of these symptoms. 

  • Abdominal bloating
  • Mild cramping due to embryo implantation or implantation cramps
  • Light spotting or implantation bleeding
  • Morning sickness and mood swings consequent of fluctuating hormones
  • Weakness, exhaustion, or fatigue
  • Tender, enlarged and sore breasts

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Things to consider at week 4 pregnancy

It is a rare chance that you may undergo an ultrasound at four weeks pregnant. But, if viewed under ultrasound, the baby looks like a minute dot called the gestational sac of around 0.04 inches. Considering how best you can take care of yourself and embryo nourishment, here are some tips to keep in mind. 

  • Start with a Healthy nutrition plan including foods rich in iron like spinach and cereals and calcium-rich foods like milk, yogurt, cheese, and paneer to help fetal bone development.
  • Avoid unhealthy eating habits and other lifestyle indulgences, including exposure to smoke. This will help keep the baby safe from congenital disabilities and pregnancy complications. 
  • Learn to relax and stay stress-free.
  • Follow an exercise module throughout the pregnancy. Include walking, swimming, stretching, and gentle exercising to be fit during pregnancy and have a hassle-free delivery. 
  • With a Doctor’s consultation, you can start with prenatal vitamins essential to support your health while taking care of the needs of the new life within you.  

Conclusion/ Take-Away

Every week of pregnancy marks something special and week 4 is the time of embryo implantation. If you want to document your pregnancy memories, start penning down the memory lane of your experiences as your young child has just begun to form itself from a gestational sac and the building blocks of organs getting distinguished. 

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Pooja N Swamy (M.Sc Biomedical Sciences)
Pooja Holds Master's Degree in Biomedical Sciences from Vellore Institute of Technology. She believes in strong research and clear understanding over the subject. Always determined and focussed with a thirst to learn new things. Hardworking, flexible and grounded to align with the goals.


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