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1 Week Pregnant: Week-by-Week Guide
2 mins read

IN THIS ARTICLE – At this stage of your journey, new developments are beginning to unfold. Check out this week-by-week guide to find out what’s in store for your baby and your body in week 1 of pregnancy.


Your baby at 1 week pregnant | Week 1 pregnancy symptoms | Prepare for your first week of pregnancy | Join Enfamil Family Beginnings



  • Which trimester is 1 week pregnant? First trimester
  • How many weeks of pregnancy are left? 39 weeks
  • How many months pregnant am I? You’re considered to be in the first month

You’re on week 1. Enjoy it, as week 2 is on the horizon! 

One of the most exciting things about pregnancy is how many changes you’ll experience with your little one over the span of just 7 days! Here’s some tips and tricks to keep on top of all that’s happening.

Your baby at 1 week pregnant

What's happening in there

  • You’re in the first trimester.
  • The countdown continues: you’ve got 39 weeks to go!

What happens during the 1st week of pregnancy?

  • You're on your period: Because it’s hard to pinpoint the exact date of conception, most OBs start counting your pregnancy from the first day of your last period, also known as LMP (last menstrual period). Consider this week one of your pregnancy journey.
  • Your body is preparing for baby: Your uterine lining is shedding, releasing last month’s unfertilized egg, and will start preparing for this month’s egg to be fertilized.

What should I be feeling at 1 week pregnant?

How big is your baby at 1 week pregnant?

At week one of pregnancy, your baby is 0 ounces, 0 inches—that’s because they haven't been conceived yet. But get ready. Once conception happens, your baby will grow and develop quickly over the next three trimesters.

Week 1 pregnancy symptoms

During week 1 of pregnancy, your body is changing quickly. As your baby grows, you will too, and there are certain pregnancy symptoms you may experience at this time.

  • Since you’re not actually expecting yet, there are no symptoms. But if you’re hoping to be pregnant soon, it’s time to get your body baby-ready. Start focusing on proper nutrition, and adopt an exercise plan if you haven’t done so already. Believe us, it’s a smart move.

Prepare for your first week of pregnancy

Help your baby even before the first week of pregnancy. Taking a prenatal multivitamin with folic acid before becoming pregnant can reduce the risk of congenital disabilities to your baby’s brain and spine. Plus, vitamins are an easy way to get essential nutrients you both need from the very start.

How to calculate your due date

Once you get that positive pregnancy test result, you can start calculating the estimated arrival of your bundle of joy. Here are two common ways:

  1. Determine the first day of your last menstrual cycle and count forward 40 weeks.
  2. Subtract three months from the first day of your last period and add on seven days.

An easy-to-use pregnancy due date calculator can help you get a better understanding of your pregnancy timeline.

Learn more about your pregnancy, including pregnancy planning and pregnancy nutrition to feel prepared to continue this magical adventure. You’re armed with the facts, what to do, and now you can take time to connect with the little one growing inside you.

With week 1 going strong, look to the future and what's coming up in week 2!

Join Enfamil Family Beginnings

You’re one week pregnant, and even though you’re not officially expecting, you can start preparing for all the excitement with Enfamil Family Beginnings. It’s the perfect resource for new and expecting moms. Save on Enfamil products, track your bump and baby’s growth, and get helpful articles each week relevant to your journey. Join now for up to $400 in free gifts.

All information on Enfamil, including but not limited to information about health, medical conditions, and nutrition, is intended for your general knowledge and is not a substitute for a healthcare professional's medical identification, advice, or management for specific medical conditions. You should seek medical care and consult your doctor or pediatrician for any specific health or nutrition issues. Never disregard professional medical advice or delay seeking medical treatment, care, or help because of information you have read on Enfamil.