Pregnancy Week 5: What to Expect
Baby's development, your body's changes, common symptoms, what to eat, and what to do this week.
Baby's development at week 5
This is a huge developmental week. Baby's tiny heart begins to beat, sometimes detectable on ultrasound by the end of the week (more often around weeks 6-7). The neural tube closes — this is why folate is critical right now. Three layers of cells have formed: ectoderm (becomes skin, nervous system, hair), mesoderm (becomes heart, muscles, bones, kidneys), and endoderm (becomes lungs, liver, digestive system). Limb buds and eye structures begin to appear as small bulges.
What's happening in your body
Your hCG is high enough that home pregnancy tests should give a clear positive. Progesterone keeps the uterine lining stable and starts to relax smooth muscle throughout your body — which is why constipation and reflux often start now. Blood volume is starting its gradual ~50% increase that will continue through the third trimester. Many people start to feel the first real wave of pregnancy symptoms this week.
Common symptoms at week 5
Morning sickness can begin (named for the time of day but often happens any time). Frequent urination as your kidneys process the increased blood volume. Strong fatigue — a deep, heavy tiredness that feels different from normal sleep debt. Tender, fuller breasts. Mild constipation or bloating. Mood shifts. Heightened sense of smell, often making certain foods (coffee, raw meat, fried foods) suddenly unbearable. Some people get all of these; some get almost none.
When to call your provider
Vaginal bleeding heavier than light spotting, severe cramping, sharp one-sided pain, or shoulder-tip pain — call your provider. Persistent fever above 101°F, or vomiting so severe you cannot keep any fluids down for 12+ hours, also warrants a call. Light spotting alone is common and usually fine, but always worth mentioning at your next visit.
How to feel better this week
If you have not already, schedule your first prenatal visit for around weeks 8-10. Stop any meds or supplements that are not pregnancy-safe — but never stop a chronic-condition medication without talking to the prescribing doctor first. Avoid hot tubs, saunas, and very hot baths (over 101°F core temperature is linked to neural tube defects). Eat small frequent meals (every 2-3 hours) to head off nausea. Vitamin B6 (10-25 mg, 3 times daily) plus doxylamine (the active ingredient in Unisom) is the evidence-based morning sickness combo — check with your provider before starting.
Nutrition focus for week 5
Iron, folate, protein, and complex carbs. If you cannot stomach much, do not panic — eat what you can keep down. Even "bad" foods (toast, crackers, plain pasta) for a few weeks will not hurt baby this early. Aim for 1.5-2 liters of fluid daily; sip rather than gulping if nausea is bad. Ginger (real ginger candy or ginger tea, not just ginger ale) can help with mild nausea.
For your partner
Be the person who keeps food in the house and does not take it personally when smells suddenly become unbearable. If your partner is dealing with nausea, do not cook foods that make it worse near them. Take over kitchen cleanup if cooking smells linger.
This week's to-do
Schedule first prenatal visit. Start tracking what foods you can/cannot eat — your provider will want a sense of your nutrition.
Is this normal?
Not having symptoms in week 5 is also completely normal. Some people sail through the first trimester with little to no nausea or fatigue. It does not mean anything is wrong — it just means you got lucky in the hormone-sensitivity lottery.
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