Calendar First Trimester

4 Weeks Pregnant

4 Weeks Pregnant: Your Checklist

  • Schedule a pregnancy confirmation appointment, if needed
  • Share the good news with your partner, and maybe a few close family and friends
  • Keep eating a healthy diet and taking your prenatal vitamins

Congratulations! You’re just 4 weeks pregnant – something you’ve just recently discovered after missing your period. A home pregnancy test should show a positive result, thanks to the hormone hCG that’s released by the brand-new placenta. Whether you’re completely thrilled about the prospect of becoming a new mom or are still getting used to the idea, now is the time to start planning while treating yourself to extra-special care.

While you’ve been adjusting to being pregnant, the new life inside you has been busy. The fertilized egg is implanting itself into the side of your uterus. It rapidly divides into layers of cells, at which point it is officially an embryo. The cell layers will grow into different parts of the developing fetus, such as the nervous system, skeleton, muscles, organs, and skin. The placenta, a disk-like organ that connects your body’s systems to that of the developing fetus, begins to form and attaches to the uterine wall where the egg is implanted. The umbilical cord comes out of one side of the placenta. The amniotic fluid, which will cushion the fetus throughout your pregnancy, is already forming inside an encircling membrane sac. At 4 weeks, your fetus has already formed a neural tube, which is the main building block for the brain and spine.

Your Baby’s Development

Four weeks into your pregnancy, your baby (now an embryo) consists of two layers of cells — the epiblast and the hypoblast. These eventually develop into all of your baby’s organs and body parts.

Two other structures that develop now are the amnion and the yolk sac. The amnion, filled with amniotic fluid, will surround and protect the growing embryo. The yolk sac will produce blood and help to nourish the embryo until the placenta takes over that role.

Your Body

The embryo continues to implant in your uterus, burying itself deep within the endometrium. Some women have slight cramping and spotting during this week while implantation happens. They might mistake this for a period, especially because this is around the time their monthly period was due.

Once implanted, the embryo starts to make a hormone called human chorionic gonadotropin (hCG), which helps to maintain the lining of the uterus. It also sends a signal to the ovary to stop releasing an egg each month, which stops your monthly periods.

hCG is the hormone that’s measured in pregnancy tests. This week, a pregnancy test probably could detect your pregnancy. hCG also causes the symptoms of pregnancy, which might start now. Tiredness, tingling or aching breasts, or nausea also can happen with premenstrual syndrome (PMS). But by the end of this week, your period won’t happen. Instead, your pregnancy is under way!

Pregnancy symptoms at four weeks

This week may be the first time you have an inkling of the changes going on inside your body. Some of the earliest signs of pregnancy include tender breasts or tingling nipples. You’ll soon notice changes in your boobs, if you haven’t already.

You may notice some light bleeding or spotting around now, or the time that you usually have your period. This is called breakthrough bleeding. This happens when the hormones that are responsible for your menstrual cycle trigger bleeding. It can happen more than once throughout your pregnancy, but is usually nothing to worry about.

What you need to know at four weeks of pregnancy

  • If you didn’t begin taking a daily folic acid supplement when you were trying to conceive, now’s the time to start. Folic acid helps to protect your baby against neural tube defects, such as spina bifida. You should take a daily supplement containing 400 micrograms (mcg) of folic acid until you’re 12 weeks pregnant.
  • You also need to take 10mcg of vitamin D every day, throughout your pregnancy and beyond. This will help your baby to grow strong teeth and bones. You can take vitamin D and folic acid as separate supplements, or as part of a pregnancy multivitamin. It’s up to you.
  • If you have diabetes or your body mass index (BMI) is above 30, you should be taking a higher dose of folic acid.
  • Your GP or midwife will prescribe this for you at your booking appointment.
  • Give your baby the best possible start with our healthy and delicious pregnancy meal planners.
  • Take a pregnancy test, if you haven’t done so already. If your previous pregnancy test was unclear, taking a second test should give you a more accurate result.

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