you're 13 weeks pregnant.
last revised · baby is about 7.4 cm (2.9") · 23 g (0.81 oz)
At 13 weeks pregnant, your baby is about 7.4 cm and 23 g — Welcome to the second trimester.
about the size of a…
Welcome to the second trimester. Your baby has unique fingerprints and can already make tiny facial expressions.
this week's highlights
- Fingerprints form
- Second trimester begins
- Facial expressions practice
- Intestines move from cord to belly
how your baby looks
Proportions are evening out — the head is now about a third of the body length. Skin is still translucent so blood vessels show through.
body in focus
- head
- Tiny facial muscles can smile, frown, and squint.
- body
- Intestines, which had been growing into the umbilical cord, move into the belly.
- hands
- Each fingertip has a unique fingerprint pattern.
- feet
- Footprints are unique too.
what's happening in your body
Energy returns for many people. You may start to show a small bump. Increased blood flow can give skin a glowing look (the 'pregnancy glow' is real).
symptoms at 13 weeks
- The second-trimester lift
- Many people cross into this trimester feeling dramatically better — more energy, less nausea, steadier moods. It is often called the honeymoon phase of pregnancy for good reason.
- Increased discharge
- Thin, milky discharge tends to increase through the second trimester and is protective. Only itching, soreness, a green tint or strong odour needs a doctor's opinion.
- Round ligament pain
- Sharp, brief pulling on one or both sides of the lower belly when you stand, twist or sneeze is the uterus's support ligaments stretching. Moving more slowly into position changes usually prevents it.
- Visible bump emerging
- The uterus is now above the pelvic brim and a genuine bump may be appearing. First pregnancies often stay subtle a few weeks longer.
- Returning libido
- With nausea fading and blood flow increased, many people find desire returns in the second trimester. Sex in a normal pregnancy is safe throughout.
- Nosebleeds
- Swollen, blood-rich nasal vessels burst more easily now. Lean forward and pinch the soft part of the nose for ten minutes; frequent heavy nosebleeds are worth mentioning at your next appointment.
gentle tips
- Buy a few maternity essentials — leggings, a stretchy bra.
- Talk to your provider about an anatomy scan in weeks 18–22.
- Start sleeping on your left side to maximize blood flow.
- Keep hydrating — your blood volume is up 30–40%.
- Use unscented lotion on a growing belly to reduce itchiness.
your week 13 checklist
- Book the anomaly (20-week) scan if your service has not scheduled it automatically
- Start researching antenatal classes and put your name down — spots fill early
- Establish a sleep set-up you can grow into: side-sleeping habit, extra pillows
- If you have not told work yet, plan the conversation — flexibility for appointments starts once they know
what to expect next
Movement may be felt for the first time between weeks 16–22, called quickening. Each person feels it on a slightly different timeline.
common questions at week 13
How big is the baby at 13 weeks?
At 13 weeks, the baby measures about 7.4 cm and weighs approximately 23 g (7.4 cm (2.9") · 23 g (0.81 oz)).
What is developing at 13 weeks?
Proportions are evening out — the head is now about a third of the body length. Tiny facial muscles can smile, frown, and squint. Key milestones this week include: Fingerprints form; Second trimester begins; Facial expressions practice; Intestines move from cord to belly.
What symptoms are common at 13 weeks pregnant?
Energy returns for many people. You may start to show a small bump. Increased blood flow can give skin a glowing look (the 'pregnancy glow' is real).
What should I do at 13 weeks pregnant?
Movement may be felt for the first time between weeks 16–22, called quickening. Buy a few maternity essentials — leggings, a stretchy bra. Talk to your provider about an anatomy scan in weeks 18–22. Start sleeping on your left side to maximize blood flow.
When does the second trimester officially start?
Definitions vary slightly, but most providers count the second trimester from the start of week 13 or 14 and running to the end of week 27. The exact boundary matters less than the pattern: for most people, this is the most comfortable stretch of pregnancy. Energy, appetite and mood commonly improve from here.
Is it safe to sleep on my back at 13 weeks?
At 13 weeks, yes — the uterus is not yet heavy enough to compress the major blood vessels that run behind it. The advice to settle on your side applies from around 28 weeks, when back-sleeping is linked to a small increase in stillbirth risk. Building the side-sleeping habit now, with a pillow between your knees, makes the later transition effortless.
Why do I feel pulling pains in my lower belly when I stand up?
That is almost certainly round ligament pain — the two ligaments anchoring the uterus stretch as it grows, and sudden movements tug them sharply. It is brief, one- or two-sided, and provoked by standing, twisting, coughing or laughing. Pain that is constant, severe, or paired with bleeding or fever is a different matter: call your midwife or doctor.
helpful tools
- Due Date Calculator
Find your estimated due date from your last period or conception date.
- Baby Names
Start exploring names — an early, joyful ritual.
Medically aligned with guidance from WHO, NHS and ACOG. How we write.