Week 5 of Pregnancy

Your Baby's Building Blocks Begin

Week 5 marks the official start of pregnancy for most people—not just emotionally, but medically. You're four weeks past your last period, and for many, this is the first week a home test turns positive. Even if you suspected something was different, that pink line (or digital "yes") hits different. Whether this was planned down to the ovulation strip or came as a surprise, Week 5 brings with it the earliest confirmation that there's a tiny life forming inside you.

But here's the wild part: even though you just found out, your baby is already hard at work. In fact, the groundwork for their entire body is being laid this week. Think of this as blueprint time—where every major organ system is starting to form, cell by cell. This is why Week 5 is often called one of the most "developmentally dense" weeks of pregnancy. And while you might not feel pregnant just yet (or feel too much, hi fatigue 👋), there's a ton going on inside both of you.

Let's break it all down.

👶 Baby at Week 5: Foundational Layers Are Forming

Your embryo is now about the size of a sesame seed—tiny, but incredibly busy. It's officially settled into the uterine lining and is developing at a rapid pace, starting with the formation of three distinct germ layers. These layers—ectoderm, mesoderm, and endoderm—are the origin story for every system your baby will eventually have.

🧠 The Ectoderm: Brain, Skin & Nervous System

This outermost layer is where the neural tube begins to form. This tube will eventually become your baby's brain and spinal cord. That's why folate (vitamin B9) is critical at this stage—it helps prevent neural tube defects. The ectoderm also lays the groundwork for skin, hair, nails, sweat glands, and even parts of the eyes and teeth.

Pro tip: If your prenatal vitamin doesn't contain folic acid or methylated folate, it's time to switch. You need 400–800 mcg daily at a minimum.

❤️ The Mesoderm: Where the Heart Begins to Beat

The mesoderm is the middle layer and home to what's arguably the most mind-blowing change this week—your baby's heart begins to beat. It's a primitive rhythm, but real. This layer will also go on to form muscles, bones, cartilage, blood vessels, the kidneys, and essential structures like the placenta and umbilical cord.

🫁 The Endoderm: Internal Organs in Progress

The innermost layer, the endoderm, starts forming your baby's internal organ systems—lungs, intestines, pancreas, liver, thyroid, and bladder. While these won't be fully functional for months, they're beginning their slow and precise development right now.

It's a lot, we know. But Week 5 is one of those magical windows where invisible miracles are happening under the radar.

🤰 Your Body at Week 5: Symptoms Can Be All Over the Place

So, what's happening to you while your baby is making organ blueprints? Short answer: possibly nothing—or possibly everything. Pregnancy is a wildly individual experience, and at Week 5, there's a huge range of what's considered normal.

Common Week 5 Symptoms

• Fatigue: This isn't regular tired—this is "I need to nap after unloading the dishwasher" tired.
• Nausea: The misnamed "morning" sickness can hit anytime, thanks to rising hCG and progesterone.
• Breast tenderness: Sore, tingly, fuller, or even darker areolas.
• Frequent urination: Increased blood flow to your kidneys can send you to the bathroom often.
• Mood swings: Blame the hormones (and the fatigue).
• Metallic taste or food aversions: Totally normal and totally annoying.

Time-saver tip: Invest in a soft, stretchy bra or wireless sports bra now. Your current ones may soon feel like medieval armor.

When You Might Feel Nothing (And Why That's Okay)

Some people have zero symptoms this early—and that's just as normal. There's no prize for suffering more. As long as you're taking care of yourself and your prenatal routine is solid, your body's doing what it needs to.

🥗 Health + Wellness: Prevent Nausea Before It Starts

You may already be noticing queasiness creeping in. Here's how to get ahead of it without turning into a full-time grazer.

Chloe's Anti-Nausea Toolkit

• Small, frequent meals: Aim for 5–6 light meals with complex carbs (toast, rice, oatmeal).
• Dry snacks at your bedside: Eat a cracker before you even stand up in the morning.
• Hydrate with intention: Sips throughout the day are better than big gulps.
• Ginger everything: Ginger chews, ginger ale, ginger tea—it actually helps some women.
• B6 supplements: Talk to your provider about this natural nausea aid.

⚠️ If your symptoms vanish suddenly or feel extreme, it's always worth a quick check-in with your provider.

📝 Tips & To-Dos: Start Capturing the Journey

This week is a great time to start documenting your pregnancy—no pressure to go full scrapbook mode, but you will want to remember these early thoughts one day.

Why Journaling Helps in Week 5

• You're still adjusting to the idea of being pregnant.
• It gives you a way to process your thoughts (excitement, anxiety, everything in between).
• You'll start noticing small changes—and they're worth tracking.

Easy Options to Start With

• Dedicated pregnancy journals with prompts
• Apps like Ovia or Nurture that let you log symptoms + milestones
• Blank notebook and your favorite pen
• Private blog to share updates with family/friends

Efficiency hack: Don't aim for perfection. Just 2–3 lines a day is enough to start building a powerful record of this experience.

🧠 Week 5 Checklist: Let's Get Organized

Must-dos:

• Confirm your positive test with a healthcare provider if you haven't already
• Schedule your first prenatal appointment (typically between Weeks 8–10)
• Begin taking a prenatal vitamin (if not already) with folate or folic acid
• Download a pregnancy tracker app
• Try smaller meals and hydration hacks for nausea
• Shop for a comfy bra or stretchy loungewear
• Start your pregnancy journal, blog, or photo diary
• Let the idea of "pregnant" start to settle in—even if it doesn't fully land yet

TL;DR: Week 5 is Quiet, but Crucial

Week 5 might feel like nothing is happening on the surface, but under the hood, everything is changing. Your baby is laying the framework for every organ and system. You're adjusting to this brand-new role—sometimes with symptoms, sometimes without. It's all valid. It's all part of the journey.

Whether you're ready to shout it from the rooftops or still wrapping your head around that little plus sign, you're doing great. One smart step at a time.