4 Weeks Pregnant – What To Expect

4 Weeks Pregnant - What To Expect

Here’s what to expect when you’re 4 weeks pregnant.

When you’re 4 weeks pregnant, this is the week your period is due … or late!

In this case, you may begin to suspect you’re pregnant and experience some symptoms of early pregnancy.

Soon you might do a pregnancy test.

Because of pregnancy hormones, women experience symptoms such as:

  • Mood swings
  • Mild cramping
  • Morning sickness
  • Implantation bleeding.

4 Weeks Pregnant – What To Expect

Generally by 4 weeks pregnant, your egg has attached to the inside wall of your uterus, or uterine lining.

The egg, now an embryo, is surrounded by fluid in the amniotic sac.

The placenta is still developing, but is sending out tiny hair-like tendrils.

These wrap around the abundant small blood vessels in the lining of your uterus.

Usually, the placenta will completely take over the role of sustaining your baby by 12 weeks gestation.

Under normal circumstances, your blood and the blood of your baby don’t mix.

You both have a separate circulatory system.

The closeness of your blood vessels to the blood vessels of the placenta allows the exchange of oxygen, nutrients and waste products.

The next six weeks are a critical stage of development for your growing baby.

For example, their organs begin to develop and some organs will even begin to work!

Cigarette Smoke When You’re 4 Weeks Pregnant

All women should quit smoking before becoming pregnant.

If you do smoke cigarettes and become pregnant, certainly now is a good time to quit.

However, while you may not be a smoker, it’s important to know exposure to cigarette smoke has negative effects on the health of pregnant women and their unborn babies.

Second-hand cigarette smoke has thousands of dangerous chemicals.

Exposure to second-hand smoke during pregnancy increases the risk of:

  • Miscarriage
  • Fetal growth restriction
  • Preterm birth
  • Low birth weight.

You can also be exposed to toxins left in places where people frequently smoke. For example on furnishings, paint, clothes, etc.

This type of exposure is third-hand smoke. Usually if a room or item smells like tobacco, it’s likely there are toxins present.

As a result, these toxins can make their way into your bloodstream and your baby’s.

There is research to show third-hand smoke can have very serious effects on your baby’s developing lungs.

Try to minimise your exposure to second and third-hand smoke as much as possible.

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4 Weeks Pregnant – Your Body

Your embryo at 4 weeks pregnant is only tiny but their presence is already being felt.

You might not feel any different or you might be wondering if you’re about to get your next period.

Pregnancy hormones start rising rapidly from now. These hormones will produce a positive pregnancy test now or in the next week.

Do you own a cat and have a litter box in the house?

It’s best to avoid cleaning the litter box due to a parasite found in some cats’ faeces.

The parasite causes toxoplasmosis and can cause serious health problems for your baby.

Rest assured, you don’t need to get rid of your cat.

Your partner can be assigned to kitty litter duty.

Early Pregnancy Symptoms When You’re 4 Weeks Pregnant

Not all women experience early pregnancy symptoms. Often these are confused with premenstrual symptoms.

Things to look out for are:

  • Bloating. You might experience fluid retention around the beginning of your period.
  • Mood swings. Fluctuating pregnancy hormones are the cause of this and are most noticeable in the first trimester. You might experience moodiness in the week leading up to you period.
  • Cramping. When the fertilised egg implants, it can cause mild cramping, similar to mild menstrual cramps. Severe cramps or pain needs to be investigated.

Folate In Early Pregnancy

You may have heard it’s important to get enough folate during pregnancy.

Folate helps the neural tube (a structure that forms the brain and spinal cord) to develop properly. It also helps prevent a major birth defect, spina bifida, from occurring by up to 70%.

During this stage of early pregnancy, your baby’s nervous system is beginning to develop.

A layer of cells fold to form the neural tube. This becomes the baby’s brain and spinal cord.

Above all, at 4 weeks pregnant it’s important to make sure your dietary intake of folate is adequate.

Dietary sources of folate include dark leafy greens, nuts, eggs, meat and chicken.

Here are 9 top foods which contain folate.

Most prenatal vitamin supplements include the synthetic form of folate (folic acid).

It’s important to note 1 in 4 people can have problems converting synthetic folate into a usable form.

It’s believed this is due to the MTHFR gene mutation, which can affect 1 in 4 people seriously, and 1 in 2 mildly.

One form of the mutation results in a 40% to 60% decreased ability to produce the body’s most active form of folate.

The best supplement to take instead is folinic acid, especially if you’ve had problems with fertility, pregnancy complications or miscarriage.

A simple saliva or blood test for MTHFR may give you some answers, so don’t hesitate to ask your doctor.

Read more in MTHFR – How 1 in 4 Pregnancies May Be Affected.

4 Weeks Pregnant – Your Baby

Your baby at 4 weeks pregnant is now classed as an embryo.

He or she has made the journey to your uterus, and has embedded in the rich lining of the uterine wall, dividing into two groups of cells.

One group of cells has become the embryo and the other has become the placenta. The placenta is truly an impressive support system for your baby. Read more in What Is A Placenta? 10 Amazing Placenta Facts.

The heart and circulatory system rapidly form. The neural tube also forms in the first 4-6 weeks of pregnancy and will develop into the brain and spinal cord.

At 4 weeks pregnant your baby is 1mm long and about the size of a poppy seed.

Here are some articles that may be helpful if you’re 4 weeks pregnant:

The TRUTH About Natural Birth
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Last Updated: October 29, 2018


Kelly Winder is the creator of BellyBelly.com.au, a writer, doula (trained in 2005), and a mother of three awesome children. She's passionate about informing and educating fellow thinking parents and parents-to-be, especially about all the things she wishes she knew before she had her firstborn. Kelly is also passionate about travel, tea, travel, and animal rights and welfare. And travel.

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