• Nutrition

4th Week of Pregnancy

embryo developing


Baby's Growth and Development When You're 4 Weeks Pregnant

This is it — the week you’ll likely miss your period and find out you're pregnant!

By your 4th week of pregnancy, your baby probably has embedded in your uterus and is growing at an amazing rate. Here’s what’s going on at 4 weeks pregnant:

When you’re 4 weeks pregnant, your baby’s body now has three distinct layers from which all of its organs will develop.

From the 3rd week of pregnancy to the end of the 4th week of pregnancy, your baby grows to the length of the head of a pin.

Your Placenta's Amazing Role

During the 4th week of pregnancy, the placenta, which will carry nutrients from you to your baby, begins to form. It’s made primarily from your baby's tissues, with the help of cells from your body. Here’s a look at what it does:

  • At 4 weeks pregnant, the placenta continues to thicken until the fourth month of pregnancy.
  • The placenta actually matches the needs of your baby with the nutrients available from you to give him the specific nutrients he needs at the time.
  • Although it’s made up of shared tissue, the placenta does not allow blood from your body and your baby's to come in direct contact.

Your Changing Body at 4 Weeks Pregnant

A husband and wife laying on top of a bed

By 4 weeks pregnant, you've missed your period. Time to test! You might be eager to find out if you have a little one on the way. Learn more about pregnancy tests:

  • Your home pregnancy test measures a hormone (hCG) that your body produces after a fertilised egg attaches to the wall of your uterus (usually six to 12 days after fertilisation).
  • Most pregnancy tests recommend waiting to test until at least the first day of your missed period.
  • The longer you wait after your missed period, the more accurate the test will be.
  • Testing too early could result in a false-negative reading of a still-developing pregnancy.

What’s the Best Time to Test?

  • Early in the morning when you urinate for the first time. The hCG hormone is at its highest level then. This is the same hormone your Healthcare Professional will check to confirm that you’re pregnant. These hCG hormone levels double every two to three days throughout your first 10 weeks of pregnancy.
  • Your Healthcare Professional might choose to check these levels in a series of tests to confirm how your early pregnancy is progressing.
  • If you test negative, but you notice other pregnancy symptoms, wait a few days and test again.

How accurate are home pregnancy tests

Most tests can diagnose 90% of pregnancies on the first day of the missed period. Wait one week after your missed period and tests jump to 97% accuracy.

Fourteen days after conception, you’re officially 4 weeks pregnant. In addition to the hormones, there’s a lot going on with your body:

  • Around your 4th week of pregnancy, the uterus begins to thicken and line with blood vessels to nourish your growing baby.
  • Your cervix, the opening in your uterus where your baby ultimately will emerge, probably begins to soften and change colour. Your Healthcare Professional may check for this to confirm your pregnancy at your first appointment.
  • Tender breasts are often one of the first changes that signal that you have a baby on the way. This tenderness usually goes away after the first few months. Your breasts might seem heavier or full.
  • At 4 weeks pregnant, you even might notice a few of the other signs of early pregnancy before you even take your pregnancy test.
  • Emotionally, you might both be thrilled and worried — or both all at once. The emotions are different for each woman, but it is common to experience a full range of them.

Wellness and Nutrition at 4 Weeks Pregnant

A lady holding pregnancy test

Congratulations! Wondering when to share the big news with others? There's no right or wrong time. It’s up to you and your partner to decide when it’s right for you to share the news. You might want to consider these Tips for Sharing Your Big News at Work.

Looking Ahead

Your pregnancy is divided into 40 weeks, or nine months, or three trimesters.

  • The 1st trimester includes weeks one through 12.
  • The 2nd trimester includes weeks 13 through 28.
  • The 3rd trimester includes weeks 29 through 40.

Scheduling With the Healthcare Professional

  • If your home pregnancy test came back positive, you might want to schedule an appointment with your Healthcare Professional. Most Healthcare Professionals will schedule the appointment between your 6th and 10th week of pregnancy. To help you get ready for that first appointment, see our 1st Prenatal Visit Checklist.
  • Becoming informed is an important part of a healthy pregnancy. But it might seem that health warnings and pregnancy recommendations are always changing. Advice now might even conflict with what you’ve learned before. Always consult with your Healthcare Professional about any questions.

Exercise — Your Pregnancy in Action

  • You’ve just received great news and might be a little cautious about doing things that could hurt your baby, especially in these early weeks and months.
  • At 4 weeks pregnant, regular exercise will continue to strengthen your body. This will help your body become better prepared to contribute to the health of your baby.

Nutrition During Your 4th Week of Pregnancy

  • Drinking enough fluids is most important early in your pregnancy. Your body begins to increase blood flow and your baby needs more fluids. Drinking enough fluids also can help you fight fatigue and possible constipation.
  • Choose water or nutritious drinks, such as skim milk or whole fruit juices.

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