Week 5 of Pregnancy
Learn about your baby's development and what to expect at 5 weeks pregnant.
Baby's Size This Week
Baby Development at Week 5
- ● Your baby is now officially an embryo, measuring approximately 2 mm (about the size of an apple seed).
- ● The heart begins to beat this week, initially as a simple tube that pumps blood — it beats about 100-160 times per minute.
- ● The neural tube, which will become the brain and spinal cord, is forming and beginning to close at both ends.
- ● Tiny limb buds are appearing where arms and legs will develop over the coming weeks.
- ● The circulatory system is the first major system to function, with primitive blood vessels forming throughout the embryo.
- ● Early structures for eyes, ears, and mouth are beginning to develop on the rapidly enlarging head region.
Your Body at Week 5
- ● Morning sickness (nausea with or without vomiting) often begins around week 5 due to rapidly rising hCG levels.
- ● Extreme fatigue is common as your body works overtime to support the developing embryo and build the placenta.
- ● Breast tenderness and swelling increase as hormones prepare the mammary glands for future milk production.
- ● Frequent urination begins as the uterus grows and presses on the bladder, and blood volume increases.
- ● Heightened sense of smell may trigger food aversions or make certain odors intensely nauseating.
- ● Emotional changes including mood swings, tearfulness, or irritability are normal due to surging progesterone and hCG.
Week 5 Checklist
- ☐ Continue taking your prenatal vitamin with folic acid every day — neural tube closure happens now.
- ☐ Manage morning sickness with small, frequent meals and ginger tea or ginger supplements.
- ☐ Stay hydrated — aim for at least 8-10 glasses of water daily, especially if vomiting.
- ☐ Rest when needed — the first trimester is the most tiring period for many women.
- ☐ Avoid exposure to toxins including harsh cleaning chemicals, paint fumes, and cat litter (toxoplasmosis risk).
- ☐ Begin documenting your symptoms to discuss at your first prenatal visit.
Frequently Asked Questions
Is morning sickness a good sign at 5 weeks?
Yes, morning sickness is actually associated with a lower risk of miscarriage. It is caused by rapidly rising hCG levels, which indicate a healthy, developing pregnancy. However, not having morning sickness is also normal — about 20-30% of women have little or no nausea and go on to have perfectly healthy pregnancies.
Can I see my baby on an ultrasound at 5 weeks?
A transvaginal ultrasound at 5 weeks may show the gestational sac and possibly the yolk sac, but the embryo itself is usually too small to see clearly. The heartbeat typically becomes visible between weeks 6-7. Most providers wait until weeks 8-10 for the first ultrasound to get the most useful information.
How big is my baby at 5 weeks?
At 5 weeks, your baby is about 2 mm long — roughly the size of an apple seed. Despite being tiny, critical development is occurring: the heart is beginning to beat, the neural tube is forming, and the foundations for all major organs are being established.
Is it normal to feel exhausted at 5 weeks pregnant?
Absolutely. First trimester fatigue is one of the most common early pregnancy symptoms. Your body is producing dramatically more progesterone, building the placenta, increasing blood volume, and supporting rapid embryonic development. This requires enormous energy. Rest when you can, and the fatigue typically improves in the second trimester.
What can I safely take for nausea at 5 weeks?
Safe options for morning sickness include vitamin B6 (25 mg three times daily), ginger in any form (tea, capsules, candies), and the combination of B6 and doxylamine (available OTC as Unisom SleepTabs). Eating small, frequent meals and avoiding an empty stomach also helps. If nausea is severe and prevents hydration or nutrition, contact your provider — prescription anti-nausea medications are available.
Track Your Exact Pregnancy Week
Use our free Pregnancy Week Tracker to find out exactly how far along you are based on your last menstrual period or due date.
Track My Pregnancy →Sources
- ACOG
- WHO Fetal Growth Charts
- Mayo Clinic
Medical disclaimer: This content is for informational purposes only and is not intended as medical advice. Always consult a qualified healthcare provider for guidance specific to your pregnancy.