First trimester · 13 weeks pregnant
Week 13: fingerprints and the end of the first trimester
The placenta is fully formed and in charge.
Unique fingerprints are forming on tiny fingertips. The placenta is now complete and producing the hormones that sustain the pregnancy, which is one reason nausea fades for many women around now.
Size and weight
About the size of
a pea pod
Length
7.4 cm
Weight
23 g
Averages from standard growth charts. Measured crown to rump until week 20 and head to heel afterwards.
How your baby is developing
- Fingerprints form; the vocal cords develop.
- The intestines are in their final position and bones are forming in the arms and legs.
- The placenta is fully formed and feeds, oxygenates and protects the baby.
- The body is catching up with the head, now about a third of total length.
How you may feel
- Round ligament pain: a sharp pull on one side when you turn or stand
- A visible bump, especially in second pregnancies
- More vaginal discharge (thin, milky, mild-smelling is normal)
- Changes in libido
- Fewer nausea episodes
This is the last week for the combined first-trimester screening. From week 14 a different blood test (the quadruple test) is used instead.
What's next
Tests and appointments
- Last week for the nuchal translucency scan (up to 13w6d).
What to do this week
- Moisturise your belly, hips and breasts; it eases itching as the skin stretches.
- Begin sleeping on your side if you can; it becomes important from 28 weeks.
- Look into antenatal classes; popular ones fill up early.
Call your doctor or maternity hospital if
- Bleeding that is heavier than light spotting, or bleeding with cramps
- Severe pain on one side of your lower abdomen, or pain with dizziness or fainting
- Vomiting so often that you cannot keep fluids down for 24 hours
- A temperature of 38 °C or higher, or pain when you pass urine
If something feels wrong, trust yourself and call 103 or your maternity hospital. You will never be wasting anyone's time.
Not sure this is your week?
Enter your last period or due date and we will show the right page and your checkup timeline.
Get this week in Telegram
Our bot sends you a short weekly digest for your exact week, your due date countdown and a list of upcoming checkups. It also knows the warning signs that need a same-day call.
- ✓A short digest every new week
- ✓Countdown to your due date
- ✓Reminders about upcoming checkups
- ✓Kick counter and contraction timer