At 8 weeks the embryo is about 15 mm — raspberry-sized — with a heart that now has four chambers and beats rhythmically. This is also the week the booking appointment window opens, and it is the longest and most thorough antenatal visit of the pregnancy.
The short answer: the heart has four chambers, the webbed fingers are separating, ears are taking final shape and the gonads are beginning to differentiate. The booking appointment is usually held between 8 and 12 weeks and covers blood group and rhesus, a full blood count, screening for HIV, hepatitis B, syphilis and rubella immunity, plus a urine test for silent infection. Organogenesis continues until around week 10, so medication safety still matters.
Your baby this week
The heart has completed its division into four chambers and is beating rhythmically, pumping blood to every developing organ. The arms and legs have lengthened enough to have distinct segments, and the webbing between the emerging fingers is beginning to break down so that individual digits separate.
The ears are reaching their final external shape, and an upper lip and the tip of the nose have appeared. Internally, the gonads are beginning to differentiate into testes or ovaries — though this is far too early to see on any scan, and sex is not usually determinable until around the anatomy scan.
Despite how much is already formed, the embryonic period continues until roughly week 10 of pregnancy. Organs are still being built rather than simply growing, which is why alcohol, unchecked medication and untreated infection still carry more weight now than they will later.
Your body this week
Your heart is working harder — cardiac output rises early in pregnancy and keeps climbing — which is part of why ordinary activity can feel disproportionately tiring. Blood volume continues its long increase towards the 40–50% above baseline it reaches later in pregnancy.
Skin often changes noticeably now, and unhelpfully it can go either way: some women become dry and sensitive, others develop acne they have not had since adolescence. Both are hormonal and both usually settle.
The uterus keeps growing and can produce a feeling of tightness or stretching low in the abdomen. Breasts are heavier and more tender; a well-fitting non-underwired bra in a natural fabric genuinely helps, and it is worth being re-measured rather than sizing up by guesswork.
Tests and appointments
Tests and scans around now: The first antenatal (booking) appointment is usually held between 8 and 12 weeks, with blood group, full blood count, and screening for HIV, hepatitis B and syphilis.
Exact timing varies by country and by your own care plan — your doctor or midwife will confirm the schedule that applies to you.
The booking appointment is the main event of this window. Alongside the bloods and urine sample, you will discuss your options for first-trimester screening — the combined test at 11–14 weeks, and NIPT where it is available — and get your dates confirmed. Bring a list of any medication and supplements, and be ready to give family history on both sides.
Blood pressure is measured at every appointment from here on. It matters because a rising blood pressure is one of the earliest signs of pre-eclampsia, and the reading is only useful against a baseline taken now.
✅ Worth doing this week
- Write down your medications and supplements before the appointment, with doses — this is the question people freeze on
- Ask both families about inherited conditions, and about twins, so the history is accurate
- Get a properly fitted bra without underwires — breasts change size several times over the pregnancy
- Report a severe headache promptly rather than waiting for the next appointment
- Do not skip the urine sample — asymptomatic infection is exactly what it is looking for
When to call your doctor
Call the same day if: you have bleeding heavier than spotting, severe or one-sided abdominal pain, shoulder-tip pain, fainting, a severe headache, a temperature above 38°C, burning on passing urine, or you cannot keep fluids down for 24 hours. One-sided pain between weeks 5 and 10 remains the classic ectopic presentation and should never be watched at home.
FAQ — 8 weeks pregnant
How big is the baby at 8 weeks?
About 15 mm crown to rump — roughly a raspberry. The arms and legs are lengthening, the webbing between the fingers is starting to separate, the ears are taking their final shape, and an upper lip and the tip of the nose have appeared on the face.
What happens at the 8-week booking appointment?
It is the longest antenatal appointment you will have. Expect a full medical, family and obstetric history, height and weight, blood pressure, and blood tests covering blood group and rhesus status, a full blood count, and screening for HIV, hepatitis B, syphilis and rubella immunity. A urine sample checks for protein, sugar and asymptomatic infection. You will also discuss screening options for the 11–14 week window, and get your due date confirmed.
Is the baby a fetus at 8 weeks?
Not quite. The embryonic period runs until about 10 weeks of pregnancy — that is 8 weeks after fertilisation, and the two-week offset is why the numbers look confusing. At 8 weeks of pregnancy the term is still embryo, and organogenesis is still under way, which is why medication safety still matters this week.
Why do I need a urine test at 8 weeks?
To check for asymptomatic bacteriuria — bacteria in the urine causing no symptoms at all. Progesterone relaxes the ureters and slows urine flow, which makes it more common in pregnancy, and untreated it can progress to a kidney infection and is associated with preterm birth. It is one of the few things screened for precisely because you cannot feel it.
Week 8 at a glance
At 8 weeks the embryo is about 15 mm — raspberry-sized — with a four-chambered heart beating rhythmically, fingers beginning to separate from their webbing, ears reaching final shape and gonads starting to differentiate. It is still an embryo: the embryonic period runs to about week 10, so organogenesis and medication safety are still live concerns. For you, this is the booking appointment window: history, height and weight, blood pressure, blood group and rhesus, full blood count, screening for HIV, hepatitis B, syphilis and rubella immunity, and a urine test for silent infection. It is also where the 11–14 week screening choices are discussed.
Inside Baby Novum: the lab results journal keeps each test with a photo of the printed report and its date, so results are in your pocket at every subsequent appointment. Blood pressure readings are plotted over time, which is what makes a rise visible rather than a single number.