Your Pregnancy Week by Week: 4 Weeks

The following information—and much more—can also be found in the free Lamaze Pregnancy Week by Week email. Sign up now to receive helpful information for your stage of pregnancy. Subscribers will be given the opportunity to complete a Lamaze Parent Satisfaction Survey after their pregnancy and receive a Lamaze Toys coupon. We want to hear about your birth experience and the impact that childbirth education may have had so that we can continue to make sure parents have the information they need for the safest, healthiest birth possible.

“Ready or not, here I come!” If your little one could speak to you right now, he or she might just pipe up with this familiar childhood phrase. You may just be finding out you are pregnant with a positive pregnancy test, while many have no idea they are pregnant for several more weeks. You may have eagerly awaited this pregnancy for months, or the news may have come as a surprise. No matter how you arrived here, you are at the start of an unforgettable journey with this tiny little life. Take this time to nourish your body and your baby and prepare for each new day of pregnancy, childbirth and parenting.

What’s new with baby?

The building blocks of your baby’s tissues and organs are organizing into a tiny three-layered disc measuring no more than 0.1inches (1.5 mm) in length. In the days ahead, these cell layers will rapidly form into the bones, skin, muscles and other organs that your baby needs.

What’s new with you?

What was your first clue that you were pregnant? Perhaps you missed a period, or you just had a hunch, or you felt a little queasy walking past the seafood market. Maybe you sensed something different about your body, little changes you’d never noticed before. Or you found your emotions were strung a little tighter than usual. You wondered: “Could I be pregnant?”

Whether you confirm your pregnancy with a home test or at a clinic, you likely knew beforehand that something was different by observing your body closely. That’s just the first of many opportunities pregnancy offers you to be mindful—to pay close attention to your body, your baby, your environment and your instincts.

If you take a quiet moment to stand before the mirror after a shower, you might notice some changes in your breasts—darker, bigger, bumpier nipples or a feeling of tenderness or heaviness. Each of these developments signals an amazing physiological process taking place inside your body as it prepares to produce milk.

Let’s Talk: Pregnancy Tests

About the time you miss your first period is the earliest you can determine you are pregnant with the use of most home pregnancy tests. Your growing baby needs time to implant into your uterus and your body needs time to produce the hormone detected in a pregnancy test (human chorionic gonadotropin, hCG).

Story From a Mama Who Has Been There

I suddenly got overwhelmed that I was bringing another baby into the world, all that responsibility. So I cried. But I think crying is healthy. I cry every day. To me, crying is like taking a yoga class. It keeps you in touch.” - Jada Pinkett Smith.

A Touch of Inspiration

“Sometimes you will never know the value of a moment until it becomes a memory.” - Dr. Seuss

Q & A with an Experienced Childbirth Educator

Question: When is the best time to take a pregnancy test?

Answer: Let's take a look at the timeline of conception and the mechanics of home pregnancy tests to better understand the best time to take a pregnancy test.

From the time of intercourse or insemination, it can take from a few hours up to 5 days for fertilization to occur, depending on when you ovulate, or release an egg. Sperm can live for approximately 5 days. A released egg is viable for 24 hours. After fertilization, it can take between 6-12 days for implantation to happen. Once the fertilized egg implants, the hormone HCG (human chorionic gonadotropin) enters the bloodstream. It is this hormone that is responsible for a positive pregnancy test.

From the time of implantation, HCG hormone levels are approximately 1-2mIU (milli international unit) and double every 48-72 hours. Any HCG level above 25mIU is considered pregnant, while less than five is considered not pregnant. The average pregnancy test detects 20-25mIU of HCG. Therefore, taking a pregnancy test 3-4 days after implantation is the earliest you could possibly test positive with a urine pregnancy test. If you're counting the time since ovulation, this would be between 9-16 days past ovulation – at the earliest.

It's important to know that not all home urine pregnancy tests are the same. Each one detects pregnancy, or HCG levels, at different mIU levels. Some early pregnancy tests will detect lower HCG levels and can give you results earlier, while others are not as sensitive. This list offers a fairly comprehensive list of brands and HCG levels. 

If 9-16 days past ovulation is the earliest you can test, what's the ideal time to test? Anything beyond 16 days past ovulation, or from the beginning of when you would expect your period. The closer to that time and in the first week after a missed period, the more accurate your pregnancy test will be. If you receive early negative tests, wait until you're closer to your expected period. While early false positives may happen as well, they are less likely. Usually, a positive pregnancy test indicates pregnancy. It's time to find an amazing care provider!

Cara Terreri, CD(DONA) , LCCE

Cara Terreri began working with Lamaze two years before she became a mother. Somewhere in the process of poring over marketing copy in a Lamaze brochure and birthing her first child, she became an advocate for childbirth education. Three kids later (and a whole lot more work for Lamaze), Cara is the site administrator for Giving Birth with Confidence, the Lamaze blog for and by women and expectant families. Cara is also a Lamaze Certified Childbirth Educator and a DONA certified doula.

Just for Fun

Curious about what people used to predict pregnancy before the pregnancy test entered our lives? Check out the history of the pregnancy test and its interesting precursors. Now to find some barley and wheat seeds...