Three is a magic number, and this week, there are lots of amazing changes happening to you and your babies-to-be. Let’s dive into what you can expect when you’re three weeks pregnant with multiples!
How are the babies?
The three-week mark is right around the time when your little bundles of joy (or rather, little bundles of cells) will be implanting into your uterus. This is considered week three of pregnancy because gestation is counted from the first day of your last period. However, implantation is the point when you’re officially pregnant.
The bundles of cells are now separating into layers. The inner cells are dividing and will make embryos (your babies’ bodies), and the outer cells are implanting into the wall of your uterus, forming protective structures called membranes, and the placenta (how the babies will get nutrients from you). As the cells continue to multiply, the embryos will grow bigger and eventually develop into the babies’ body parts and organ systems.
Another cool thing about the three-week mark? The embryos already have genetically predetermined hair and eye color.
What’s new with you?
You’re getting closer to being able to take a pregnancy test, though you might want to wait until after your missed period to get the most accurate result. At-home tests measure the hormone hCG, which begins to be released after implantation and doubles about every 48-72 hours throughout the first trimester.
If you’re pregnant with multiples, you might have higher levels of hCG early on. That said, an ultrasound won’t be able to confirm you’re pregnant with multiples until close to six weeks.
While it might be too soon to take a pregnancy test or get a sonogram, you could start experiencing some early pregnancy symptoms during week three. You might notice light spotting, which could be a sign of implantation. Bloating, mild cramping, and sore breasts are also common during the very early weeks of pregnancy. And those carrying twins or multiples might experience more intense symptoms than people pregnant with one baby.
As you wait to take a pregnancy test, we recommend taking prenatal vitamins, eating nutritious foods, and staying hydrated. And pay attention to how you’re feeling. With lots of changes on the horizon, it’s essential that you take care of your mental health, too.
Reviewed by the Ovia Health Clinical Team
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Sources
- Mayo Clinic Staff. Fetal development: The 1st trimester. Mayo Clinic. Updated March 2025. Web. https://www.mayoclinic.org/healthy-lifestyle/pregnancy-week-by-week/in-depth/prenatal-care/art-20045302.
- MedlinePlus. Fetal development. U.S. National Library of Medicine. Reviewed 8/23/2023 https://medlineplus.gov/ency/article/002398.htm.
- American Pregnancy Association. What is HCG? 2020. Web. https://americanpregnancy.org/getting-pregnant/hcg-levels-71048/.
- Singh, N. et al. Role of early serum beta human chorionic gonadotropin measurement in predicting multiple pregnancy and pregnancy wastage in an in vitro ET fertilization cycle. Journal of Human Reproductive Sciences. 2013. Web. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3853879/.
- Horsager-Boehrer, R. MD. Patience is key: Understanding the timing of early ultrasounds. The University of Texas Southwestern Medical Center. 2018. Web. https://utswmed.org/medblog/patience-key-understanding-timing-early-ultrasounds/.
- Cleveland Clinic. Expecting Twins or Triplets. 2020. Web. https://my.clevelandclinic.org/health/articles/9710-expecting-twins-or-triplets.
