4th Week Pregnancy: Symptoms, Baby Development, Tips And Body Changes

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You must have missed your period and done a pregnancy test. The test showed positive, and when you count you realize that you have already covered three weeks of pregnancy!

Now, you are in the fourth week, and by this time, your body is undergoing changes with new hormonal secretions.

MomJunction tells you about the size of your baby, their development, your pregnancy symptoms and the care you need to take in the fourth week of pregnancy.

How Many Months Is 4 Weeks Pregnancy?

If you are four weeks pregnant, then it means you are in the first trimester and about to complete one month of pregnancy. In addition to a missed period, your body begins to send other signs of pregnancy by now.

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What Are The Symptoms Of The Fourth Week Pregnancy?

Here are the symptoms you may experience during this week:

  1. Bloating
  2. Mild cramping and spotting if implantation of the embryo takes place in this week
  3. Morning sickness and nausea
  4. Fatigue and sleepiness
  5. Tenderness of breasts and fuller breasts as they start to prepare for milk production
  6. Frequent urination
  7. Emotional changes such as anxiety and mood swings

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[ Read: Signs Of Twin Pregnancy ]

Symptoms of twin pregnancy:

The symptoms of a twin pregnancy are the same as those of a singleton pregnancy. However, the intensity of symptoms such as nausea, urge to urinate, etc., might be higher in a twin pregnancy than in a singleton pregnancy.

Moreover, the pregnancy symptoms start showing up much earlier than in the singleton pregnancy.

These symptoms mean that your baby has begun growing inside.

How Big Is Your Baby In 4 Week Pregnant?

Your baby is in its embryonic stage. By this week, the embryo measures around 0.04in (1.02mm) in length and about the size of a sesame seed (1).

As it is the early stage of your baby’s development, let’s see how the embryo is developing inside the womb.

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How Is The Baby Growing Inside You?

Once the embryo attaches to the uterine lining, it starts producing a hormone called human chorionic gonadotropin (hCG). This hormone maintains the endometrium lining and signals the ovary not to release any more eggs for the coming months (2).

The embryo comprises three layers ectoderm, mesoderm, and endoderm that later form the organs and the tissues of the baby’s body. Their functions are described below (3):

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  • The ectoderm (outer layer) is responsible for the formation of nervous system and brain, skin, nails, hair, sweat glands, ears, mammary glands, and teeth enamel.
  • The mesoderm (middle layer) forms the circulatory system, heart, connective tissues, urogenital system, skeleton, and the muscles.
  • The endoderm (inner layer) will develop into lungs, respiratory system, gastrointestinal tract lining, pancreas, liver, and thyroid.

Two structures, namely amnion and yolk sac, are formed during this week.

An amniotic sac, also called amnion, starts forming to support and cushion your baby. This sac is filled with amniotic fluid that provides a favorable environment for the embryo.

  • The yolk sac is responsible for the formation of blood cellular components.
  • Also, the outer embryonic membrane called chorion starts forming the placenta.

[ Read: How Big Is Your Baby? ]

Here is how the organs are developing at the initial stage.

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Baby Development At 4th week

Body organsDevelopmental stage
Heart (4)Begins to beat at the rate of 105 to 121 times/minute
Blood vesselsBlood circulation starts
Limb buds (5)Start appearing
Pharyngeal archesBegin to form the neck and head
ForebrainBecomes prominent
EyesBegin to appear

The fourth week is probably the first time you see an OB/GYN because you know you have missed your period. She would suggest you undergo a few tests.

Pregnancy Tests In This Week

Here are the preliminary tests done in the fourth week:

  1. Pregnancy test: A pregnancy kit looks for the traces of hCG in your urine. This week, the hCG levels in urine may or may not be high enough for the kit to detect. If you get a negative result but still miss your period, then wait for a week and do the test again.

Alternatively, a blood test can confirm your pregnancy in this week as the hCG level in blood is high by this time.

  1. Ultrasound: Generally, an ultrasound is not done in this week as it shows just the gestational sac. The embryo can be detected only a few weeks after the fourth week. In the case of multiple pregnancies, two distinct gestational sacs (fraternal twins) or multiple embryos in one sac (identical twins) are visible.

During your first visit to the doctor, she will prescribe some prenatal vitamin supplements to balance your intake.

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[ Read: 2nd Week Pregnancy ]

Tips For Pregnancy Week 4

Here are some tips you can follow to have a healthy pregnancy:

  • Schedule an appointment with the doctor.
  • Drink a lot of water and keep yourself hydrated.
  • Follow a healthy diet. Eat foods that are rich in vitamins, minerals, and protein. Consume lean meat, cereals, dairy products, fresh and natural foods (fruits and vegetables).
  • Eat small and frequent meals to relieve morning sickness. Nibble some crackles that are rich in carbohydrates.
  • Avoid consumption of caffeine and alcohol.
  • Avoid fried and fatty foods as well as excess salty and sugary foods.
  • Do not diet or fast because lack of nutrients can affect fetal development.
  • Talk to your partner about your concerns and discomforts. He will understand what you are going through and help you feel better.
  • Stay connected with family and friends for emotional support. It can keep you mentally strong, especially if it is your first pregnancy.
  • Rest well and relax.
  • Do not take any medication without discussing with your doctor. If you are on any medication even before getting pregnant then tell your doctor about it.

Supplements To Take During The Fourth Week Of Pregnancy

If you haven’t yet started on folic acid supplements, you need to begin them now. The vitamin is necessary to prevent any birth defects. Taking folic acid in the recommended amounts during pregnancy can reduce the chances of autism disorders as well as neural tube defects by 50-70% (6).

You may also need to take supplements for iron, calcium, and vitamin D, depending on your body’s requirement, which your doctor will assess.

In addition to the supplements, you need to enhance the nutritional value of your diet:

  • Have yogurt, cheese, milk, and green leafy vegetables for calcium
  • Eat chicken, fish, meat, iron-fortified cereals and beans for iron
  • Salmon fish and milk provide you with vitamin D

Confirmation of pregnancy brings happiness and new-found zeal into your life. But you need to be aware of the possible risks to your pregnancy.

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[ Read: 3rd Week Pregnancy ]

Possible Risks In The Fourth Week Of Pregnancy

It is not necessary that you fall in the risk zone, but it is good to be aware of them.

Ectopic pregnancy:

During the fourth week, there is a chance of an ectopic pregnancy (7). It happens when the fertilized egg attaches itself outside the uterus and not inside. The place of implantation can be the fallopian tube, cervix, ovary or the cornua.

The symptoms of an ectopic pregnancy are similar to those of normal pregnancy in the initial stage. However, the signs get distinct as the weeks pass. They include:

  • Heavy nausea and vomiting
  • Light vaginal bleeding
  • Abdominal pain and cramps
  • Weakness
  • Pain in the neck and shoulders
  • Rupture of the fallopian tube leading to heavy bleeding and immense pain

2. Miscarriage:

During the fourth week, there is a risk of a miscarriage due to any underlying health issues or an unhealthy lifestyle. An early miscarriage can occur even before the woman knows about her pregnancy. Around 10-20% of women are susceptible to early miscarriages (8).

  • The symptoms of miscarriage include:
  • Bleeding, brown discharge, bright red spotting or blood clots
  • Tissues sloughed off through the vagina
  • A gush of pink vaginal fluid
  • Abdominal pain or cramps
  • Early pregnancy symptoms disappear slowly
  • Dizziness and light-headedness

If you notice any of the symptoms, see your doctor soon.

The news of pregnancy brings along several questions. Below we answer some of the most common ones.

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[ Read: What Causes Miscarriage ]

Frequently Asked Questions:

1. How is pregnancy calculated?

Pregnancy is usually counted from your LMP i.e., the first day of your last menstrual period. However, the doctors use an obstetric calculator to evaluate the initial due date. The full term is around 40 weeks. But the delivery can take place between 38 and 40 weeks.

2. What if I get fever and cold during week 4?

If you catch a cold without fever during the fourth week, then just stay at home, take steam and have warm water and herbal tea.

In the case of fever, if the temperature is above 38oC, then it creates an unfavorable environment for the embryonic development. Therefore, see your doctor.

3. Can alcohol consumption affect the fetal development?

If taken in excess amounts, alcohol can adversely affect the fetus. Keep away from alcohol for the first few weeks of pregnancy or a few months before getting pregnant.

4. What if I get a negative result in the pregnancy test at four weeks?

As mentioned in the above context, you might get a false negative result because the hCG level is still not detectable in the urine. In such a case, do the home pregnancy test again after few days of missing your period. If you are in doubt, get a blood test done.

5. Is sex safe during the fourth week?

It is safe to have sex during this week as it doesn’t harm the embryo. Generally, many women might not be aware of pregnancy unless they miss their period and take a pregnancy test.

Your pregnancy has just begun. You are likely to see several ups and downs through your journey until the delivery. You are elated about the development but at the same time exhausted. Therefore, eat healthy, be active, keep away from negative emotions and take care of yourself.

Do you want to share your pregnancy experience with other readers? Write to us in the comment section below.

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