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3 Weeks Pregnant: Week by Week Pregnancy

Symptoms, Tips and Fetal Development


Congrats, you made a baby! Although your baby is technically a ball of cells (sometimes called a blastocyst), those cells are now dividing rapidly and increasing exponentially. Here’s more about what happens at three weeks pregnant.

Baby at 3 weeks

At fertilization, sperm meets egg and within hours begins the process of dividing again and again. Within days, that little miracle has become a microscopic ball of cells. This tiny (about ⅕ the size of a period at the end of this sentence) life begins the journey from the fallopian tube to the uterus.

You may not yet feel like you're going to have a baby, but at three weeks pregnant, your child is growing inside you. It's already either a girl or a boy, although it will be several weeks before your doctor will be able to determine its sex.

Your body at 3 weeks pregnant

human embryo at 3 weeks

When you are pregnant at three weeks, your body begins transforming itself so that it can properly grow and protect your baby.

Three weeks pregnant ultrasound

Your teeny, tiny baby is too small to be seen on most ultrasounds.

Three weeks is how many months pregnant? 

At this stage in your pregnancy, you're just under one month (0m3w) pregnant.

Common symptoms at 3 weeks pregnant

Your symptoms at three weeks pregnant are probably undetectable (or easily confused with PMS). Although some women say they get a feeling or intuition that they are pregnant, most women who have conceived are blissfully unaware at three weeks pregnant. 

Here are some early signs that you might be pregnant:

  • Breast tenderness. Your breasts may be starting to swell a bit and you may experience some tenderness.
  • Mild cramping and/or light spotting. You could experience a small amount of bleeding and cramping at implantation, when the fertilized egg attaches to the wall of the uterus.
  • Feeling dizzy or fainting. The pregnancy hormones and the low blood sugar and low blood pressure that often come when you’re expecting can cause extreme dizziness and even fainting spells.
  • Headaches. Pregnancy hormones can cause pretty killer headaches in some women almost right away. 
  • A heightened sense of smell. Pregnancy hormones kick your sniffer into high gear, for better or worse. And smells that didn’t bother you before might be extremely off-putting when you have a baby on board!
  • Metallic taste in your mouth. Another symptom to blame on pregnancy hormones, which can make your taste buds go all kinds of crazy.

Pregnancy checklist at 3 weeks pregnant 

If you’ve been trying to get pregnant, you’ve probably begun adopting lifestyle changes in anticipation of growing a baby. Things like eating well, drinking a lot of water, limiting caffeine, maintaining a healthy weight, ditching drugs and alcohol, and getting regular exercise aren’t just good for you, they’re also crucial to having a healthy pregnancy. 

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