Week 18 opens the anomaly scan window, the most detailed scan most women have. Some feel the first movements around now, described almost universally as a gentle fluttering. A dark line may appear down the middle of the stomach, which is pigment and nothing else.
Your body this week
Clumsiness is common as the bump changes your balance. Breasts may have gone up a size, particularly in a first pregnancy.
Blood pressure is often a little lower than usual at this stage, so standing up quickly can leave you dizzy. Getting up slowly is the whole of the advice.
The line down the stomach is called the linea nigra. It is ordinary skin pigmentation and usually fades in the months after birth.
What you may notice
Stretch marks, tiredness and sleep problems, sore gums, round ligament pains, headaches, nosebleeds, bloating and constipation, indigestion and heartburn, sore breasts, leg cramps, feeling hot, dizziness, swollen hands and feet, urine infections, vaginal infections, and skin and hair changes.
Movements, if they have started, feel like bubbling or fluttering rather than kicks. Many women feel nothing for another month, particularly in a first pregnancy, and that is not a warning sign at 18 weeks.
Your baby this week
Around week 18, the length quoted is about 14.2cm from head to bottom — bell pepper-sized, in the NHS's comparison. Averages describe a population, and an individual scan measurement is a conversation with a sonographer rather than a verdict.
Hearing, feeling, swallowing and sucking reflexes are developing this week, and there is a lot of movement of arms and legs.
What care usually happens around now
The anomaly scan is offered in England between 18 and 20 weeks. It is a detailed look at physical development: the brain, heart, spinal cord, face, kidneys and abdomen, and the position of the placenta.
Two things are worth understanding before you go. It looks for a specific list of conditions and cannot pick up everything, so a scan that finds nothing is reassuring rather than a guarantee. And the sonographer is working, not commentating — long silences during the scan are normal and rarely mean anything.
The sex can sometimes be seen at this scan. Not every service tells you, and if you do not want to know you must say so before it starts. Scan timing and policy differ between countries.
This week's tip
Decide before the appointment whether you want to be told the sex, and tell the sonographer at the start rather than when they ask. It is the one thing at this scan you can control, and it is much harder to un-hear than to not ask.
When to see a doctor
Report bleeding, severe pain, a fever, or a headache with vision changes. If movements have started and then reduce or change, contact your maternity service the same day. Pregnancy warning signs has the full list.
Seek care now: Contact your local emergency services or go to your nearest emergency department if you have heavy bleeding, severe or one-sided tummy pain, a severe headache with vision changes, sudden swelling of the face or hands, a fever, fluid leaking from the vagina, chest pain, trouble breathing, fainting, or a seizure. Femio cannot assess a pregnancy.
Frequently asked questions
Does a normal anomaly scan mean everything is fine?
It means nothing was found on the list the scan looks for. It is genuinely reassuring, and it is not a guarantee, because some conditions cannot be seen on a scan.
Why was the sonographer so quiet?
Because measuring takes concentration. Week 19 covers the same window, and week 17 covers the first movements. If you want to be told what is being looked at as it happens, say so at the start.