Week 4 Pregnancy: Exciting Developments You Need To Know

Welcome to the fourth week of your pregnancy journey! While there isn’t a baby bump yet, big changes are already coming your way. This early, you may already have an inkling of what is to come. Therefore, you need to be aware of what is going on and what you can do to make this week easier.

How Is Your Baby’s Development?

During the fourth week of pregnancy, you might not realize you are pregnant yet. That is because your baby, while already starting to grow, is still about the size of a poppy seed. There won’t be any obvious belly growth yet, which should happen between the first and second trimesters.

At this point, your baby is known as an embryo. It begins to grow the cells that will become its organs. It is also covered in an amniotic sac, which provides the nourishment it needs. Cleveland Clinic points out that, “By the end of the fourth week, the blastocyst is about 2 millimeters (mm) long — the size of a poppy seed.”

It is also during this week when your body prepares to provide what your baby needs while they develop. While the embryo grows inside the amniotic sac, the placenta is also forming. It develops during pregnancy and provides oxygen and nutrients to your baby in the later months.

Hormonal Changes While 4 Weeks Pregnant


After your baby has implanted itself, your body produces a certain pregnancy hormone. It is human chorionic gonadotropin (hCG) detected by pregnancy tests

It increases your body’s production of estrogen and progesterone. They thicken your uterine lining and stop the monthly release of eggs. It prevents your body from ovulating during pregnancy.

Estrogen and progesterone help maintain the pregnancy until the placenta is fully developed. The increased production of these hormones can also lead to symptoms in the next few days.

What Pregnancy Symptoms Will You Feel?

You may start feeling hormone-related symptoms in your 3rd week. Not every pregnancy is the same for every to-be mother. That means you may not experience all the symptoms listed here. However, it is still a good idea to know what to expect.

A Missed Period

This is often one of the first signs of pregnancy. Assuming you have a regular menstrual cycle, it is a reliable way to tell if you are pregnant. This symptom results from pregnancy hormones preventing ovulation. But you still need a pregnancy test because a missed period can result from many other things.

A Metallic Taste In Your Mouth

While the cause of this is not completely understood, it is believed to result from pregnancy hormones. Known as dysgeusia, you may experience this by the fourth week. 

This metallic or sour taste can be unpleasant. Fortunately, there are ways to make this symptom bearable. Eating sour candies and other acidic food is a good way to counter dysgeusia. You can also rinse your mouth with saltwater.

Heightened Sense Of Smell

During the fourth week of pregnancy, it’s not uncommon to experience a heightened sense of smell. This increased sensitivity to odors comes from your body’s increased hormone production. You may find yourself noticing scents that you never noticed before. Strong-smelling foods may become unbearable too. 

Unfortunately, this symptom can contribute to morning sickness. To alleviate it, avoid strong odors when possible. You can also try using scented candles or diffusers to fill the air with pleasant scents.

Mild Cramps


One of the common signs of pregnancy is cramps. While worrying, this may simply be caused by the fertilized egg implanting itself into your uterus. This happens before it becomes an embryo. The implantation causes increased blood flow and thickening of the uterine lining, leading to cramps.

Should your cramps cause severe pain, a visit to the doctor is advised.

Implantation Bleeding

This type of bleeding happens due to the implantation of the fertilized egg. The blood can look similar to a very light period or spotting. But it’s different from your period due to the hormonal changes in your body. This bleeding comes from blood vessels affected by the implantation process.


While inconvenient, nausea is a common pregnancy symptom. You can also experience it later or earlier in your pregnancy. Despite being known as morning sickness, it can affect you at any time. But don’t worry, as this does not mean anything bad for your baby. It also won’t last throughout your pregnancy, usually disappearing by the second trimester.

Mood Swings


“Hormonal changes during pregnancy often cause sharp mood swings,” according to the NIH. Early pregnancy is already a time of change. Your body is changing, and so will your lifestyle. In addition to your hormones, the anxiety from this life-changing moment can weigh on your emotional health. Mood swings during pregnancy are common and will level out in time. Find time to rest, relax, and do things you enjoy.

Tender Breasts

You can expect some changes in your breasts, such as tenderness and heaviness. Your nipples may also become sore and sensitive. 

While normal, some women find that sore breasts are painful, while others barely notice it. These symptoms result from hormonal changes and are meant to prepare for breastfeeding. 

To alleviate discomfort, wear supportive bras that fit and lift your breasts.

Taking Care Of Yourself While 4 Weeks Pregnant

Make Your First Prenatal Appointment

If you’ve got a positive pregnancy test result, visit an OB/GYN. This is very important as you need prenatal care as early as week 4 pregnancy. Also, visiting an OB/GYN now will save you time in looking for the best one for you. 

It will be the first of many regular checkups. Your doctor will track your progress and help you take care of yourself as the weeks go by.

Eat A Healthy Diet

A healthy lifestyle is crucial during this stage. It is also a good idea to prepare your body for the challenging phases of pregnancy. You can accomplish this by eating healthy food. According to the American Pregnancy Association, “You also want to be careful about the different medications you take during pregnancy.” It may also be beneficial to start taking prenatal vitamins, especially ones high in folic acid.

Try to include a variety of fruits, vegetables, and lean proteins in your meals. Also, prenatal vitamins and mineral supplements can help you get the nutrients you need. 

Aim to include the following in your diet: 

  • Folic acid
  • Vitamins B, C, & D
  • Iron
  • Calcium
  • Choline
  • Omega-3 fatty acids

Exercise Regularly

week 4 pregnancy


Try working out to prepare your body for the challenges of pregnancy. Go for exercises that build cardio, core, and back strength.

Activities that can help achieve this are aerobics, yoga, and weight training. The beauty of doing them is that you don’t need to sign up for a gym membership. You can just get an exercise mat and a resistance band and do it at home!

Avoid Unhealthy Habits and Activities

Your health should be your number one priority if you are pregnant. Make sure you stay away from activities that will endanger your well-being. 

That includes avoiding foods with too much sugar or saturated fats. You should also stop drinking alcohol and too much coffee. 

Smoking is also another habit to stop. As much as possible, do what you can to avoid secondhand smoke too.

Kathy Urbanski

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