Watch our video guide to Week 5 of your pregnancy journey:
What's Happening in Week 5?
Your baby is now approximately 2mm long — about the size of a sesame seed. Small as that sounds, an extraordinary amount of development is already underway.
The embryo is made up of three distinct layers that will form every organ and tissue in your baby's body:
- Ectoderm (outer layer): will become the nervous system, brain, skin, hair, and nails
- Mesoderm (middle layer): will form the heart, circulatory system, bones, muscles, and kidneys
- Endoderm (inner layer): will develop into the lungs, intestines, and liver
Most importantly, the neural tube — which becomes your baby's brain and spinal cord — is beginning to form this week. This is exactly why folic acid supplementation is so critical right now.
Your baby's heart is also beginning to develop. It starts as a simple tube-like structure and may begin to beat for the first time around this week, though it's often not detectable on ultrasound until week 6 or later. Early facial features are starting to take shape, with tiny pits forming where the nose will be and depressions where the eyes will develop.
Your Body This Week
This is often the week when women discover they're pregnant, usually prompted by a missed period. Your body is producing rapidly rising levels of hCG (human chorionic gonadotropin) — the hormone detected by pregnancy tests — which roughly doubles every 48-72 hours.
Common symptoms you may start to notice:
- Fatigue and exhaustion: often one of the earliest signs, driven by high progesterone levels
- Nausea: morning sickness may begin, though it more commonly starts in week 6. Despite the name, it can strike at any time of day
- Breast tenderness: breasts may feel swollen, heavy, or tingling
- Frequent urination: your kidneys are working harder and the growing uterus presses on the bladder
- Mood swings: hormonal fluctuations can cause emotional ups and downs
- Light spotting: some women experience implantation bleeding, which can be mistaken for a light period
Don't worry if you have very few symptoms — many women feel perfectly normal at this stage, and that's not a cause for concern.
Scans and Medical Care
Can you see anything on ultrasound at 5 weeks? A transvaginal scan would typically show only a gestational sac and possibly a yolk sac at this stage. A heartbeat is unlikely to be visible this early — it's more reliably detected from week 6-7 onwards. If you're anxious, most clinics recommend waiting until at least 7 weeks for an early reassurance scan, when a heartbeat can usually be confirmed.
In Ireland, the HSE recommends contacting your GP as soon as you know you're pregnant to arrange antenatal care. Under the Maternity and Infant Care Scheme, combined care between your GP and maternity hospital is provided free of charge.
Essential Nutrition
- Folic acid: the HSE recommends 400mcg daily during this critical period, as the neural tube is actively forming. Speak to your GP about supplementation
- Vitamin D: the HSE recommends 15mcg daily
- Hydration: aim for 8-10 glasses of water daily, especially if experiencing nausea
- Small, frequent meals can help manage nausea — bland, carbohydrate-rich foods like crackers, toast, and plain rice tend to settle the stomach
- Iron-rich foods: lean red meat, beans, lentils, and fortified cereals. Pair with vitamin C (orange juice, peppers) to enhance absorption
- Foods to be cautious with (per HSE guidance): raw or undercooked meat, unpasteurised cheeses (brie, camembert), raw shellfish, liver products, and alcohol
Common Concerns at Week 5
Miscarriage worry is very common in early pregnancy. The overall risk is approximately 10% of clinically recognised pregnancies, with 80% of losses occurring in the first trimester. While this statistic can feel daunting, it also means that the vast majority of pregnancies progress normally.
Ectopic pregnancy symptoms typically appear between weeks 5-14. Warning signs include one-sided lower abdominal pain, vaginal bleeding (often dark and watery), and shoulder tip pain. If you experience these, seek urgent medical attention.
Spotting in early pregnancy is common and often harmless, but any bleeding should be reported to your GP or midwife.
This article is for general information purposes only and is not intended as medical advice. Every pregnancy is different. Always consult your GP, midwife, or healthcare provider for guidance specific to your circumstances.
See your baby's heartbeat with an Early Pregnancy Scan at Ultrasound Ireland — we recommend booking from 7 weeks for the best experience.