Week 5 Pregnancy: Symptoms, Due Date & Baby

Katie GriffinOnline Childbirth Classes for Natural Birth, Pregnancy

Week 5 Pregnancy - Symptoms, Due Date & Baby

You’re 5 weeks pregnant and you have officially missed a period!  And if your pregnancy test wasn’t positive last week, you now have enough human chorion gonadotropin (HCG) in your system to register a strong positive on a urine test.  Mixed with the dizzy euphoria of finding out that you’re pregnant, you likely have lots of questions about what’s going on inside your body in week 5 pregnancy.  Let’s jump on in!

Week 5 Pregnancy:  Baby’s Development

At 5 weeks pregnant–just 3 weeks from conception–your baby is changing rapidly but hasn’t grown much in length from week 4.  Baby now measures about 1.25mm, or .05 inches long (1).

At 5 weeks, your baby looks more like a piglet than a baby. It’s true. Give him a few more months and he’ll be a whole lot cuter. Promise.

Although teeny-tiny, your baby is doing some pretty incredible things this week.  For example:

  • Baby’s beating heart is now visible on an ultrasound
  • Eyes begin to appear — they look like shallow grooves on either side of the brain
  • Baby’s skeleton is starting to form
  • Arm and leg buds are visible
  • Brain has differentiated into 5 different area

Week 5 Pregnancy - Baby's Development

Week 5 Pregnancy:  Symptoms

There are a lot of changes going on inside your body, although you likely won’t be aware of most of them.  The biggest symptom you’ll notice this week is a missed period.

Missed Period

It’s time for a quick biology lesson!  Each month, your body thickens up the lining of your uterus, a blood and nutrient-rich layer known as the endometrium.  If you don’t get pregnant, this layer sloughs off and your period begins.

But, you ARE pregnant!  Your fertilized egg traveled from the fallopian tubes into the uterus where it implanted in the endometrium for nourishment. (Learn about Implantation Bleeding in Week 4 Pregnancy.)  Implantation triggered your body to start producing human chorion gonadotropin (HCG).  In addition to tipping off a positive urine pregnancy test, HCG signals your ovaries to produce more estrogen and progesterone.  (It’s also responsible for the morning sickness you’re likely to start feeling soon :/)

Estrogen and progesterone tell your body NOT to have a period, but instead to start growing the placenta.  (Progesterone also turns up your internal heat, leading to those uncomfortable night sweats.)  Once it’s fully developed, the placenta will become a life-giving organ for your baby, delivering all of the oxygen, nutrients, and hormones that your baby needs to develop.  The umbilical cord grows out of the placenta, forming the connection between you and your baby (2,4).

Week 5 Pregnancy - Missed Period

Week 5 pregnancy - Placenta and Umbilical Cord

Week 5 Pregnancy:  How is the Due Date Calculated?

Last Menstrual Period

The average length of human gestation is around 280 days, or about 40 weeks, from the day of your last menstrual period (LMP).  The due date is calculated by simply taking the first day of your LMP and adding 280 days on to it.

For instance, if your LMP was January 1st, the calculation would go as follows:

January 1 + 40 weeks = Estimated Due Date October 8th


But what if you can’t remember your LMP but you know for sure when you ovulated?  There’s pretty strong evidence that conception occurs within 24 hours after ovulation, so the day of ovulation is often used to mark the beginning of a pregnancy.  The average time from ovulation to birth is 268 days (38 weeks, 2 days).  So, if necessary, you can calculate your estimated due date by adding 268 days to the day that you ovulated.

Due Date is Just an Estimate

Remember that the due date is merely an estimate and certainly not a prediction of the actual day your baby will be born.  Studies have shown that only 4% of women will deliver at 280 days, and still, only 70% will deliver within 10 days of the estimated due date.  This holds true even when the date is estimated by ultrasound, which is considered to be more accurate (3).  Plan to deliver sometime within 2 weeks before or after your estimated due date.

Week 5 Pregnancy Tip:  Focus on Folic Acid

You’ve probably heard about the recommendation to take folic acid at least 1 year before conception.  But if you haven’t jumped on the folic acid bandwagon yet, the time to begin is now!

Week 5 Pregnancy - Folic Acid

Folic acid is also known as vitamin B9 or folate.  Before pregnancy and during the first 12 weeks of pregnancy, the recommendation is to take 400 micrograms of folic acid daily.  Now is the time in pregnancy where baby’s spinal cord is developing.  Studies have found that taking folic acid during this important period can significantly reduce baby’s risk of developing neural tube defects such as spina bifida and anencephaly.

In addition to vitamin supplementation, folic acid is also found in of the foods you’re already eating.  It’s added as a supplement to most fortified breads, cereals, and pastas.  It occurs naturally in foods such as:

  • asparagus
  • avocados
  • bananas
  • black beans
  • broccoli
  • citrus
  • egg yolks
  • green beans
  • leafy green vegetables (spinach)
  • lentils
  • liver
  • strawberries

Still, it’s difficult to get the recommended amount of folic acid from a healthy diet alone.  For this reason, continue to take a daily vitamin supplement containing folic acid throughout your pregnancy (1,3).

Kopa Birth’s online childbirth classes allow you to prepare for a natural childbirth from the comfort of your own home, 24/7. Enroll today in our free online childbirth class to learn more about preparing for a natural hospital birth.


(1) Glade, B.C., Schuler, J.  (2011).  Your Pregnancy Week by Week, 7th edition.  First Da Capo Press.

(2) Ladewig, P.A., London, M.L., Davidson, M.R.  (2006).  Contemporary Maternal-Newborn Nursing Care, 6th edition.  Pearson Prentice Hall.  Upper Saddle River, NJ.

(3) Jukic, A. M., Baird, D. D., Weinberg, C. R., McConnaughey, D. R., & Wilcox, A. J. (2013). Length of human pregnancy and contributors to its natural variation. Human Reproduction (Oxford, England)28(10), 2848–2855. http://doi.org/10.1093/humrep/det297

(4) The American College of Obstetricians and Gynecologists.  (2010).  Your Pregnancy and Childbirth Month to Month, 5th edition.