Pregnancy Week By Week

What to Expect in Week 3 of Your Pregnancy

Third Week of Pregnancy: Week by Week

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Welcome to your pregnancy journey! Your journey officially started two weeks ago, but the magic starts to happen around this time. Before this week, you were menstruating (week 1) and then getting ready to ovulate (week 2) – not much happening in terms of creating a tiny human. While it makes sense to think of week 1 as the official beginning of your pregnancy, your egg (or eggs in the case of twins) has not been fertilized until this point. During week 1, you were menstruating, and during week 2 your body was getting ready to ovulate, or release an egg.


Week 3 is when the exciting things start to happens. Your egg is released from your ovary and a sperm fertilizes it. The egg/sperm combo begins to divide into many cells: the beginning of the development of your son or daughter.

Early Pregnancy Signs, Symptoms and What to Expect

At this point, your body will likely not feel any different. Since implantation has not occurred yet, hormone levels remain relatively unchanged. You are so early in the process that most over the counter pregnancy test will likely not be able to tell you that you have a baby-on-board.

Baby’s Development

Your baby is going from a sperm and an egg to around 100 cells this week. Your baby is itty-bitty at this point and it is hard to imagine that in 9 months you will be cradling it in your arms. Isn’t the miracle of life amazing?

3 weeks pregnant belly size

Your belly during your third week of pregnancy will more than likely not look any different than it did a few weeks ago. Your uterus and baby are still small…for now…

Ultrasound at 3 weeks pregnant

It is very rare for ultrasounds to be conducted at this point. Your egg is fertilized, but it is still very small: possibly too small to even be detected by an ultrasound. Sorry guys, no cool images to show.


If there is any possibility of you being pregnant, stop drinking alcohol, smoking cigarettes, and doing any recreational drugs.

Make sure you are taking a high-quality prenatal vitamin.

Eat a pregnancy-friendly diet. Choose foods like leafy green veggies, legumes, nuts, and whole grains. Limit foods that are fried or high in refined sugar.

Just relax and breathe. You are about to be embarking on the most amazing journey.

Shopping List

Invest in a good-quality prenatal vitamin. Some qualities to look for include:

  • At least 500 mcg of folic acid/folate
  • At least 200 mg DHA omega-3 fatty acid
  • At least 150 mcg iodine

Making sure you are getting some supplemental choline is a wise idea as well, as choline has been shown to support baby’s brain development.

Try some sparkling water varieties if you need an alcohol-free swap.

Specific Posts


This article is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.

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Lauren Manaker About Author

Lauren Manaker is an award-winning registered dietitian, certified lactation counselor, and book author. She sits on the executive committee of the Women's Health Dietetic Practice Group of the Academy of Nutrition and Dietetics and is on the Breastfeeding Advocacy committee. Lauren is an infertility survivor, mom-of-one, rescue pup lover, and wife to a very lively husband. She lives in Charleston, SC.

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