Week 11 opens the first-trimester screening window — the one appointment in pregnancy with a hard deadline. It is also the week the placenta starts taking over hormone production from your ovary, which is why nausea usually begins easing soon.
Your baby is about 45 mm and 7 grams — fig-sized, and growing fast.
The short answer: the combined first-trimester screening — a nuchal translucency scan plus a blood test — runs from 11 to 14 weeks and cannot be done later, because the nuchal measurement is only valid while crown-rump length is between about 45 and 84 mm. The placenta is becoming self-sufficient and will soon take over progesterone production. The fetus is swallowing and "breathing" amniotic fluid to train the lungs and gut.
Your baby this week
The head is still roughly half the total length, but the torso is stretching out and the proportions will shift noticeably over the next month. Active swallowing of amniotic fluid has become routine, and the fetus also draws fluid in and out of the developing lungs — a rehearsal that trains the muscles and helps the lungs develop, long before there is any air to breathe.
The external genitals are beginning to form, though they look similar in both sexes at this stage and a sonographer will not reliably be able to tell you the sex yet. NIPT can, from a blood sample, if that has been done.
Fingernails are appearing, the diaphragm is forming, and hair follicles are developing on the skin.
Your body this week
This is the peak week for placental development. The placenta is becoming increasingly autonomous and will shortly take over progesterone production entirely from the corpus luteum in your ovary. That handover is a big part of why first-trimester nausea typically begins to lift between weeks 12 and 14.
Your metabolic rate is high, which means increased thirst and a persistent sense of warmth. A linea nigra — a dark vertical line down the abdomen — may start to appear; it is pigmentation, it is harmless, and it fades after birth.
Calf cramps and a feeling of tightness in the uterus are common now. If cramps are disturbing your sleep, magnesium is worth raising with your doctor rather than self-prescribing, since dose and formulation matter.
Tests and appointments
Tests and scans around now: The first-trimester combined screening — nuchal translucency scan plus a blood test — is offered between 11 and 14 weeks.
Exact timing varies by country and by your own care plan — your doctor or midwife will confirm the schedule that applies to you.
The combined test has two parts done at the same visit: the nuchal translucency measurement on ultrasound, and a blood test measuring PAPP-A and free beta-hCG. Together with your age these produce a probability — for example 1 in 1,500 — not a yes or no. A higher-chance result leads to a discussion about NIPT or a diagnostic test such as CVS or amniocentesis, and the choice is yours at every step.
The same scan confirms your due date, checks that the pregnancy is viable, and identifies twins — including whether they share a placenta, which changes how the pregnancy is monitored and is much harder to determine later.
✅ Worth doing this week
- Confirm the scan is booked within 11–14 weeks — this is the deadline that cannot move
- Decide in advance what you would do with a higher-chance result, so the decision is not made in the moment
- Do not stand still for long periods; if your legs ache, elevate them above heart level
- Ask about magnesium if calf cramps are waking you, rather than buying a supplement blind
- Use sun protection daily — it limits how dark the linea nigra and facial pigmentation become
When to call your doctor
Call the same day if: you have bleeding heavier than spotting, severe or one-sided abdominal pain, a severe headache with visual disturbance, fainting, a temperature above 38°C, burning on passing urine, or persistent vomiting you cannot control. Calf pain that is one-sided, hot, swollen or tender is different from a cramp and needs urgent assessment for a clot.
FAQ — 11 weeks pregnant
What is the nuchal translucency scan?
An ultrasound measuring the fluid-filled space at the back of the baby's neck, done between 11 and 14 weeks. A thicker measurement is associated with a higher chance of Down syndrome and some heart and structural conditions. It is normally combined with a blood test measuring PAPP-A and free beta-hCG, and the result is a probability, not a diagnosis. The scan also confirms dates, checks viability and detects a twin pregnancy.
Why does the screening window close at 14 weeks?
Because the nuchal measurement is only reliable while the crown-rump length is between roughly 45 and 84 mm — which corresponds to about 11 to 14 weeks. After that the fluid reabsorbs and the measurement stops meaning anything. This is the one screening window in pregnancy that genuinely cannot be reopened, which is why booking it matters more than any other appointment.
How big is the baby at 11 weeks?
About 45 mm crown to rump and around 7 grams — roughly a fig. The head is still about half the total length, but the torso is starting to lengthen and the proportions will change quickly over the next month.
What is the linea nigra?
A dark vertical line running down the middle of the abdomen, caused by the same pregnancy hormones that increase pigmentation elsewhere. It usually appears in the second trimester but can start now, is more noticeable on darker skin, and fades over the months after birth. It is harmless and there is nothing to do about it — sun protection helps limit how dark it and other pigmentation get.
Week 11 at a glance
Week 11 opens the 11–14 week screening window, the only appointment in pregnancy with a genuine deadline: the nuchal translucency measurement is valid only while crown-rump length is between about 45 and 84 mm. The combined test pairs that scan with a PAPP-A and free beta-hCG blood test and returns a probability, not a diagnosis. Your baby is about 45 mm and 7 grams, swallowing and rehearsing breathing with amniotic fluid, with external genitals beginning to form. The placenta is becoming self-sufficient and will soon take over progesterone production — the handover behind the nausea easing from weeks 12 to 14.
Inside Baby Novum: the appointment calendar marks the 11–14 week window from your own dates and warns before it closes, and the ultrasound journal stores the nuchal measurement and the printed report together so the numbers are with you at the follow-up.