12 weeks pregnant

Your baby at 12 weeks

At 12 weeks you are near the end of the first trimester, the stretch in which the major organs form. Because pregnancy is dated from the first day of your last period, and conception usually happens about two weeks after that, your baby has been developing for roughly ten weeks.

ACOG's guide lists what happens across weeks 9 to 12. The kidneys have begun making urine, the pancreas has started producing insulin and the liver is developing. Fingernails are forming. The eyelids have formed but stay closed for now, and the genitals are beginning to form. Cartilage for the arms, legs, hands and feet is in place and will harden into bone over the coming weeks.

A scan this early cannot show every limb and organ in detail. ACOG explains that a first-trimester ultrasound is mainly used to count the babies, estimate how far along you are and support screening. The detailed anatomy check comes later, usually between 18 and 22 weeks.

The size figures on this page come from two places. The fruit and the length beside it are the comparison used in the ProbaBaby app. The scan measurement is the INTERGROWTH-21st standard, built from 4,265 healthy pregnancies in eight countries, and it gives the middle crown–rump length at exactly 12 weeks plus the range most healthy babies fall in. Babies grow fast in these weeks, so a measurement taken a few days later in the week will be noticeably longer.

Your body at 12 weeks

You may not look pregnant to other people yet, though some people start to see a small bump around now. Inside, your uterus is expanding and the placenta keeps growing; it is the organ that passes oxygen and nutrients to your baby and carries waste away.

Tiredness is common. The NHS says it is especially likely in the first 12 weeks, when hormone changes can leave you exhausted, queasy and emotional at once. Rest when you can, and accept offers of help.

The first antenatal visits usually fall around now. In England the first full midwife appointment, often called the booking appointment, happens between 8 and 12 weeks and can take about an hour. Your blood pressure and urine are checked, you are offered blood tests including your blood group, and you are asked about your health, past pregnancies, mental health and home life. The list of tests in the block below shows what is usually due in this window.

Common symptoms around 12 weeks

• Nausea and vomiting. Morning sickness can happen at any time of day. Among the NHS suggestions: sip fluids little and often, rest when you can, and keep meals small, frequent and plain, with cold food if hot smells set you off. Ginger may help; check with a pharmacist before taking ginger supplements.
• Food aversions. Foods you used to enjoy can suddenly seem unbearable. Eat what you can manage, and steer clear of foods and smells that make you feel sick.
• Needing to pee more often. This is a normal early sign of pregnancy as long as there is no pain or burning. Do not cut back on drinks to avoid trips to the toilet; you need the fluids, especially if you are being sick.
• Heartburn. The NHS notes that indigestion becomes more common from 12 weeks onward. Smaller meals and sitting upright after eating can help.

Tips for this week

• Prepare for the dating scan. Ask whether you need a full bladder, and bring your notes if you have paper ones. In England the scan usually takes about 20 minutes.
• Decide about screening before the appointment. The combined test pairs a blood test with the neck fluid measurement on the scan. It is offered for Down syndrome, Edwards syndrome and Patau syndrome, and it is your choice whether to have it. ACOG adds that cell-free DNA testing can be done from 10 weeks, with results in about a week.
• Think about when to share your news. Some people wait until after the first scan. There is no rule: tell people when it feels right, and consider who you would want to lean on if you needed support.
• Keep moving gently. The NHS says exercise is safe in pregnancy and it is usually fine to continue what you already do. Aim for about 150 minutes of moderate activity a week, and start anything new gently.

When to call your doctor or midwife

Some signs need your emergency number and some need a call the same day. Call your local emergency number now for heavy bleeding, severe pain, feeling faint or pain at the tip of your shoulder. For light spotting or mild cramps, contact your midwife or doctor that same day; under 20 weeks an early pregnancy unit may see you, and your local non-emergency health line is the fallback if you cannot get through.

• Call the same day if you have light vaginal bleeding or spotting, even if it is painless or comes with mild cramps only.
• Call your emergency number if you are bleeding heavily, or bleeding with severe belly pain, pain in your shoulder, or feeling faint or dizzy.
• Call now if you cannot keep food or fluids down for 24 hours, if your pee is very dark or you have not peed for more than 8 hours, or if you feel very weak, dizzy or faint when you stand up.
• Call now if you are vomiting and also have belly pain, a high temperature, or blood in your vomit.
• Call now if peeing hurts or burns, especially with a fever or pain in your side. The NHS notes that urine infections can also cause sickness and can spread to the kidneys.