13 Weeks Pregnant: Baby, Body and What to Expect

Week 13 at a glance

At 13 weeks, your baby is about 7 to 8 cm (2.8 to 3.1 inches) long, roughly the size of a pea pod. The major organs and body systems have formed, and the focus now shifts to growth and maturation.

13 weeks pregnant is about 3 months. You are in month 3 of pregnancy and the first trimester.

Your baby at 13 weeks

Your baby is about the size of a pea pod

This is an important milestone: the major organs and body systems have formed.

What this means

By week 13, the main organs and body systems are in place. Development now focuses on growth, refining tissues and building the abilities each organ needs to work well.

The heart, brain, kidneys and digestive system continue to mature.
Facial features become more defined.
The placenta plays an increasingly important role in providing nutrients and oxygen.

Week 13 is the last week of the first trimester. Many people find that nausea and fatigue start to ease in the second trimester, though this varies from person to person.

Checkups and tests around this time

Your provider may confirm your due date with an ultrasound and check your baby's growth and development. Many people are offered prenatal screening tests around this time, such as NIPT (a blood test that looks at fetal DNA in your blood) or first-trimester screening. Ask your OB-GYN or midwife which tests are offered, what they can and cannot tell you, and whether you want them.

Call your OB-GYN or midwife right away if you have bleeding, severe pain, fever, persistent vomiting, fluid leaking from the vagina, or a sudden change in how you feel. Do not wait for your next scheduled visit.

See week 13 in 3DNova shows how your baby grows each week and keeps a symptom log for your doctor. Try Nova

Your body at 13 weeks

Why morning sickness may start to ease

Relief often comes around this time

Many pregnant people look forward to week 13. For some, this is when the body seems to settle down. Researchers believe a major cause of first-trimester nausea is the rapid rise in hCG, a hormone the placenta needs to develop. hCG levels usually peak around weeks 8 to 11 and then level off.

By this point, the placenta is taking over more of the work of supporting the pregnancy, and hormone levels often become more stable. Many people notice that nausea and vomiting become less intense during the second trimester, though some people have symptoms for longer.

What you may notice at 13 weeks

Better appetite and a return of normal food tastes for some people.
Less sensitivity to smells.
Mood that feels more even as hormone levels settle.
More energy, which some people describe as a second-trimester boost.

Every pregnancy is different. If nausea continues past week 13, that does not automatically mean something is wrong. Your body may adjust at its own pace.

When to call your doctor

Morning sickness usually improves, but call your OB-GYN or midwife right away if you cannot keep fluids or food down for 24 hours, feel dizzy or faint, have very little urine, notice rapid weight loss, or have vaginal bleeding, fluid leaking from the vagina, severe belly pain, or a fever.

Common symptoms at 13 weeks

Easing nausea

Morning sickness often starts to lessen around this time. Small, frequent meals and snacks with protein or crackers can help keep your stomach settled.

Fatigue

Tiredness is common as your body works hard to support the pregnancy. Short rests, earlier bedtimes, and asking for help with chores can make a real difference.

Breast tenderness

Your breasts may feel sore, swollen, or more sensitive. A well-fitting, supportive bra, including a sleep bra, may feel more comfortable.

Frequent urination

You may need to pee more often as your uterus grows and presses on your bladder. Staying hydrated during the day and limiting drinks close to bedtime may help.

Constipation or bloating

Hormone changes can slow digestion, which may cause gas or hard stools. Fiber from fruits, vegetables, and whole grains, plus regular water and gentle movement, may help.

Mood changes

Mood swings or feeling more emotional are common during early pregnancy. Talking with a partner, friend, or your care team about how you feel can help, and reach out sooner if sadness or worry feels heavy or lasts.

Your week 13 checklist

Keep a simple list of questions for your next prenatal visit. Take your prenatal vitamin with folic acid as your care team recommended. Drink water regularly through the day, and keep a bottle nearby. Eat small, regular meals and snacks rather than large ones. Ask your care team about any new or worsening symptoms, including severe nausea or vomiting. Plan for rest, such as a short nap or an earlier bedtime when you can.

Tests and appointments

First-trimester screening. Some people are offered a screening blood test and an ultrasound measurement of the back of the baby's neck, often between about 11 and 14 weeks.
Chorionic villus sampling (CVS). Some people may be offered this optional diagnostic test, usually between about 10 and 13 weeks, if screening results or family history suggest it.
Prenatal visit and blood work. Your care team may check your weight, blood pressure, and urine, and may review routine blood tests from your first prenatal visit.

For your partner: You can help by taking on extra household tasks, like cooking, cleaning, or grocery shopping, especially on days when nausea or fatigue feels strong. Going to appointments together and asking questions with your partner can also help you both feel informed and supported.

Questions about week 13

How many months is 13 weeks pregnant?

13 weeks pregnant is about 3 months. You are in month 3 of pregnancy and the first trimester.

What trimester is 13 weeks?

Week 13 is in the first trimester. The first trimester runs through week 13, the second from week 14 to 27 and the third from week 28 until birth.

What is happening with the baby at 13 weeks?

At 13 weeks, your baby is about 7 to 8 cm (2.8 to 3.1 inches) long, roughly the size of a pea pod. The major organs and body systems have formed, and the focus now shifts to growth and maturation.

Why does morning sickness start to get better around week 13?

Many people notice nausea easing as hormone levels become more stable. Not everyone's experience is the same, and some people have symptoms for longer. If nausea is severe, keeps you from eating or drinking, or causes weight loss, contact your OB-GYN or midwife.

Is it normal to feel tired even when the nausea improves?

Yes, fatigue is common in early pregnancy and can continue for a while. Rest when you can, eat regular meals, and let your care team know if tiredness feels extreme or is affecting your daily life.

What should I eat if I can't keep much down?

Many people find bland, easy-to-digest foods like crackers, toast, bananas, rice, or yogurt more tolerable. Sipping fluids slowly may help too. Ask your care team for personalized guidance if you're struggling to keep fluids down.