Week 12 · First trimester

Your baby this week

Baby is about the size of a lime.

5.4 cm
estimated length: 14 g
estimated weight

Averages only — babies grow at their own pace, and a scan measurement is the one that counts.

Average growth guide

The step at week 20 is the measuring convention changing — head to bottom before, head to toe after.

Week12

First trimester

Developing now

Reflexes are developing — baby can curl fingers and toes.

How you may feel

Often a little more energy as the first trimester closes.

See tips

Often around now

Dating scan · around week 12A general guide to UK antenatal care — your midwife will confirm yours.

More about week 12

What's happening now

Reflexes are arriving: the baby will curl their fingers and toes, and their mouth will make sucking movements. The kidneys are producing urine into the amniotic fluid, which the baby then swallows and recycles — a system that will run until birth. The digestive system is practising the muscular squeeze it will use to move food along.