How many months is 13 weeks pregnant?

13 weeks pregnant puts you in month 3 of pregnancy. Week 13 is the last week of that month, and month 4 starts at week 14. Providers count in weeks; months are approximate.

How big is the baby at 13 weeks?

At 13 weeks, the baby is about the size of a lemon, roughly 7.4 cm long and around 23 g. That is an average; healthy babies vary.

Are there symptoms of having a boy or girl at 13 weeks?

No. Nausea, cravings, skin changes, bump shape and heart rate don't reliably predict sex. In a study of 477 pregnancies, first-trimester heart rates were almost the same for boys and girls. Some scans try to guess from the angle of the 'nub' between the legs. In a US study of routine scans at 11 to 13 weeks, this guess was right 85.8% of the time. Cell-free DNA screening, from 10 weeks, can report sex chromosomes. The anatomy scan at 18 to 22 weeks usually can too, if the baby's position allows.

Can I lie on my belly at 13 weeks pregnant?

Yes. The NHS says sleeping on your stomach is fine in early pregnancy. At 13 weeks your womb has only just started to rise out of your pelvis, so lying on your front is unlikely to feel uncomfortable yet. As your bump grows, you'll probably find it harder and can switch to your side. Advice to fall asleep on your side rather than your back applies from 28 weeks.

Can you feel baby flutters at 13 weeks?

Probably not yet, even though the baby is moving a lot. First movements, called quickening, usually start at 16 to 20 weeks. People who have been pregnant before tend to notice them sooner, around 16 weeks, while in a first pregnancy it is often closer to 20 weeks. Early movements feel like flutters or bubbles and are easy to mix up with gas. If you don't feel anything at 13 weeks, that is normal.

Is cramping normal at 13 weeks pregnant?

Mild cramps and twinges are common as your womb grows up and out of your pelvis. Short, sharp twinges low on the side of your belly are often round ligament pains. They come from the ligaments that hold the womb as they stretch. Constipation and trapped wind can also cause cramps. Call your provider or maternity unit straight away if cramps are regular or come with tightenings, bleeding, fluid leaking, lower back pain, or pain when you pee, or if severe pain doesn't settle after 30 to 60 minutes of rest.

Is it normal to not feel pregnant at 13 weeks?

Yes. For many people, early symptoms fade around now. In a study of 363 women who kept daily diaries, nausea stopped on average at about 12 weeks, and for 4 in 10 it stopped quite suddenly. Losing symptoms at this stage does not by itself mean there is a problem. The best signs that things are going well are normal checkups and scans. Contact your provider if symptoms stop along with bleeding, cramps or fluid leaking, or if you're simply worried.

13 Weeks Pregnant

At 13 weeks pregnant, your baby is about 7.4 cm long, around the size of a lemon. The ovaries or testes are fully formed inside, the vocal cords are forming, and the large head is starting to grow more in proportion to the body. Sources don't agree on this week: Cleveland Clinic counts it as the last week of the first trimester, while the NHS and the US Office on Women's Health put it in the second. Either way, many people start to feel better now. This page covers the 13-week ultrasound, your growing bump, whether you can lie on your belly or feel flutters, cramping, and boy-or-girl myths.

What trimester is 13 weeks?

Week 13 is in the second trimester, which runs from week 13 to week 27 (NHS). It is week 1 of 15 in this trimester, and the third trimester starts at week 28.

Week 13 — second trimester, month 3; 27 weeks to go until your due date.
Baby's size — about a lemon, ~7.4 cm.

Not sure it's 13 weeks? Try our due date calculator.

★ First week of the second trimester (NHS).

How big is your baby at 13 weeks?

Size of a

lemon

Length, head to bottom

~7.4 cm

Weight

~23 g

Up from a lime last week to a lemon now.

Baby development at week 13

The start of the second trimester (NHS; some US sources count it as the last week of the first). Vocal cords are forming, and the large head is starting to grow more in proportion to the body. The gut, which grew partly into the umbilical cord for a few weeks, is now back inside the abdomen, and the bones keep hardening. About the size of a lemon.

What an ultrasound shows at 13 weeks

In the UK, the dating scan is offered from 8 to 14 weeks, so for some people it falls in week 13. It is usually done through your tummy. You may see the baby's face in profile, the arms and legs, and movements that are starting to look more deliberate and less jerky. The heart rate has settled a little from its peak around week 9, to an average of about 159 beats per minute in one study.

Week 13 is near the end of the window for nuchal translucency screening. It can only be measured while the baby is 45 to 84 mm long, and after about 14 weeks the fluid is reabsorbed and hard to measure. At about 7.4 cm, your baby is near the top of that range. If you miss it, a second-trimester blood test called the quad screen can be done instead. This is also the last week the head-to-bottom length is normally used for dating: if it differs from your period dates by more than 7 days, your due date is usually changed.

If you're carrying twins, the scan should check by 14 weeks whether they share a placenta, because that decides how closely they'll be watched. Some people hope to learn the sex at this scan, but finding out the sex is not what it's for.

Your body at 13 weeks

Energy often improving as the second trimester begins
Nausea fading for most
A more visible bump

Your belly at 13 weeks

A small bump may start to show around 13 weeks, as your womb grows upwards and outwards out of your pelvis. The top of it is now just above your pubic bone, and by about 16 weeks it will be roughly halfway to your belly button. As the womb moves up and away from your bladder, you may need to pee less often.

First-time parents often look only a little thicker around the middle for now, and some don't show until after 20 weeks. Those who have been pregnant before may show from 12 to 14 weeks. Brief, sharp pains on the sides of your belly are also common as the womb gets bigger. This is called round ligament pain.

Tips for week 13

Energy often returns in the second trimester, so it can be a good time to plan gentle exercise
Start thinking about maternity clothes as your bump grows
Keep up balanced meals and hydration

13 Weeks Pregnant: your questions

What trimester is 13 weeks?: Week 13 is in the second trimester, which runs from week 13 to week 27 (NHS). It is week 1 of 15 in this trimester, and the third trimester starts at week 28.
How many months is 13 weeks pregnant?: 13 weeks pregnant puts you in month 3 of pregnancy. Week 13 is the last week of that month, and month 4 starts at week 14. Providers count in weeks; months are approximate.
How big is the baby at 13 weeks?: At 13 weeks, the baby is about the size of a lemon, roughly 7.4 cm long and around 23 g. That is an average; healthy babies vary.
Are there symptoms of having a boy or girl at 13 weeks?: No. Nausea, cravings, skin changes, bump shape and heart rate don't reliably predict sex. In a study of 477 pregnancies, first-trimester heart rates were almost the same for boys and girls. Some scans try to guess from the angle of the 'nub' between the legs. In a US study of routine scans at 11 to 13 weeks, this guess was right 85.8% of the time. Cell-free DNA screening, from 10 weeks, can report sex chromosomes. The anatomy scan at 18 to 22 weeks usually can too, if the baby's position allows.
Can I lie on my belly at 13 weeks pregnant?: Yes. The NHS says sleeping on your stomach is fine in early pregnancy. At 13 weeks your womb has only just started to rise out of your pelvis, so lying on your front is unlikely to feel uncomfortable yet. As your bump grows, you'll probably find it harder and can switch to your side. Advice to fall asleep on your side rather than your back applies from 28 weeks.
Can you feel baby flutters at 13 weeks?: Probably not yet, even though the baby is moving a lot. First movements, called quickening, usually start at 16 to 20 weeks. People who have been pregnant before tend to notice them sooner, around 16 weeks, while in a first pregnancy it is often closer to 20 weeks. Early movements feel like flutters or bubbles and are easy to mix up with gas. If you don't feel anything at 13 weeks, that is normal.
Is cramping normal at 13 weeks pregnant?: Mild cramps and twinges are common as your womb grows up and out of your pelvis. Short, sharp twinges low on the side of your belly are often round ligament pains. They come from the ligaments that hold the womb as they stretch. Constipation and trapped wind can also cause cramps. Call your provider or maternity unit straight away if cramps are regular or come with tightenings, bleeding, fluid leaking, lower back pain, or pain when you pee, or if severe pain doesn't settle after 30 to 60 minutes of rest.
Is it normal to not feel pregnant at 13 weeks?: Yes. For many people, early symptoms fade around now. In a study of 363 women who kept daily diaries, nausea stopped on average at about 12 weeks, and for 4 in 10 it stopped quite suddenly. Losing symptoms at this stage does not by itself mean there is a problem. The best signs that things are going well are normal checkups and scans. Contact your provider if symptoms stop along with bleeding, cramps or fluid leaking, or if you're simply worried.

Useful at week 13

Baby gender predictor — for fun only, while you wait for a real answer
Pregnancy weight gain calculator — your healthy range as the second trimester begins
Exercise in pregnancy — staying active safely into the second trimester
Flying while pregnant — what to check before you book a trip
Pregnancy weeks to months — 13 weeks is the last week of month 3

← All weeks: the full pregnancy week-by-week guide

Sources

Checked against the following public guidance on October 2, 2026. Advice can differ between countries; your doctor, nurse or midwife can apply it to you.