Week 4 Pregnancy: Symptoms & Early Signs of Pregnancy

Week 4 Pregnancy - Symptoms and Early Signs of Pregnancy

You’ve likely just found out that you’re expecting! (In fact, many women don’t know yet at this point.)  With the nerves and adrenaline rush of a positive pregnancy test, your life has officially changed forever.  Congratulations!  You are a mama-to-be!  At week 4 of your pregnancy — just 2 weeks out from conception — your body is at the start of an amazing journey to parenthood. Kopa Birth® is honored to share this experience with you!

Estimated reading time: 6 minutes

Updated July 9, 2021

The First Weeks of Pregnancy

Before we jump into week 4 of your pregnancy, let’s briefly recap what you missed in the weeks before you found out you were pregnant.

Week 1 – This was the first day of your last menstrual cycle.  You weren’t actually pregnant yet. (This is because we start counting pregnancy at the first day of your menstrual cycle, but conception doesn’t occur until a couple weeks later.)

Week 2 – You still weren’t pregnant at this point.  Your body was busy preparing the lining of the uterus for potential implantation.

Week 3 – This is the week in which you ovulated and had sex.  The sperm cell and your egg cell then met in the fallopian tube and conception occurred.  With time, the fertilized embryo (aka. the ball of cells that will become your baby) made its way to the uterus for implantation.

Week 4 Pregnancy:  How big is your baby?

Now you’ve arrived at week 4 of gestation.  Your baby is 2 weeks old (per the conception date) and is growing and changing rapidly!  He or she measures about 1mm in length.  For a frame of reference, one millimeter is half the size of the letter “o” on the page… the same size as a poppyseed.  That’s a teeny little ball o’ cells 🙂 (1).

Week 4 Pregnancy - How big is your baby
At week 4, your little one is about the size of a poppy seed. Don’t you worry…he or she will get a whole lot cuter in a couple months 😉

Baby’s Development

Your baby’s cells are multiplying RAPIDLY.  At the same time, they’re starting to differentiate into the various functions they’ll take on as the body grows.  Liver cells, blood cells, and neurons all begin to form a distinct identity and purpose (2).

Other notable developmental milestones include:

  • Baby’s liver begins to function
  • Kidneys and heart are forming
  • Blood is beginning to circulate
  • The neural tube, which ultimately becomes the brain and spinal cord, is developing
  • Amniotic sac is forming

Can you believe that all of that happens in just two weeks since conception?! Pregnancy is incredible!

Week 4 Pregnancy - Baby Development
It may not look like anything in this picture — just an illustration of where your uterus sits in your body. (With your teeny baby inside.) But in coming weeks, these pictures will give a really cool look at where your baby is inside your body!

Week 4 Pregnancy:  Symptoms

You’re probably oblivious to most of the changes going on inside your body at this early stage in the pregnancy.  But you may notice some symptoms associated with implantation — the process in which the embryo burrows safe and snug into the nourishing uterine wall.

Week 4 pregnancy - Implantation bleeding

Implantation Bleeding

Tiny blood vessels in the uterine lining can get disrupted as the embryo implants there.  A very small amount of light bleeding can occur as a result.  This is normal and harmless.

The bleeding that occurs with implantation will be very light in color and flow — probably just a few drops of blood.   You may initially mistake it for the start of your menstrual period; however, it won’t get heavier and dark in color like a typical period.

Week 4 Pregnancy:  Early Signs of Pregnancy

Again, you very well may not have any symptoms this early. Don’t worry if you don’t. Some women are very sensitive to the hormone shifts of early pregnancy, so it is possible that you might have some symptoms. Some common early signs of pregnancy that you might experience at week 4 in your pregnancy include:

  • A missed menstrual period. For most women, this is the first sign of pregnancy. It happens because of a shift in hormones in your body, and may be largely due to the rise in progesterone to help your body maintion the pregnancy.
  • Sore breasts. Your breasts may feel tender or tingly, may feel full or heavy, and the areola may look darker.
  • Slight cramping or tenderness in the abdomen. Some women feel a bit of cramping, similar to menstrual cramps.

Many of the earliest symptoms of pregnancy are similar to the premenstrual symptoms that many women experience, so a pregnancy test is the only way to know for sure what’s causing your symptoms.

Week 4 Pregnancy - Early Signs of Pregnancy

Week 4 Pregnancy Tips

Watch What You’re Putting in Your Body

Now is the time to take a hard look at your medicine cabinet.  Even prescription and over-the-counter drugs that are normally safe can potentially lead to birth defects or fetal harm when taken during pregnancy.  Discuss all medications with your health care provider. Even though your first prenatal appointment won’t be for another month or so, you can absolutely call to get advice about what medications are safe. Don’t take anything new, but also don’t abruptly stop taking any prescriptions that you’ve been taking without talking to your doctor about whether they’re safe to continue through pregnancy, and if not, whether you can stop them abruptly or need to make a plan for doing so.

The CDC’s resource page for medicine and pregnancy is a good place to gather information, but remember that this website should not be used in place of talking to your own doctor or midwife. Your caregiver is always the best source of information.

Also, if you smoke, drink, or take any recreational drugs, it is important for your health and your baby’s that you discontinue use right away.

Prenatal Vitamins

Also, begin taking a prenatal vitamin if you weren’t already taking one before conceiving. Believe it or not, your poppyseed-sized little one already is already developing essential body systems and needs things like folic acid that prenatal vitamins provide.

Again, congratulations on your pregnancy!  Join us again soon to learn all about Week 5 of your pregnancy!

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


  1. Glade, B.C., Schuler, J.  (2011).  Your Pregnancy Week by Week, 7th edition.  First Da Capo Press.
  2. Ladewig, P.A., London, M.L., Davidson, M.R.  (2006).  Contemporary Maternal-Newborn Nursing Care, 6th edition.  Pearson Prentice Hall.  Upper Saddle River, NJ.

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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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You’ve likely just found out that you’re expecting! (In fact, many women don’t know yet at this point.)  With the nerves and adrenaline rush of a positive pregnancy test, your