Your Baby's Development at 13 Weeks

What Are My Baby’s Weight and Size at 13 Weeks?

When you are 13 weeks pregnant, your baby weighs about 2.58 ounces (about as much as a small apple) and is about 2.64 inches (6.7 cm) from crown to rump (baby’s legs cannot be measured because they are curled up).

Development Milestones at 13 Weeks

Your placenta has fully formed and is supporting your pregnancy. This is a temporary organ within your uterus that provides oxygen and nutrients to your baby and gets rid of waste from your baby like carbon dioxide, urea (a compound), and bilirubin (the yellow pigment in stomach fluids). The placenta also makes the hormones progesterone and estrogen, which help to maintain your pregnancy.

By now, your baby's eyelids have fused together to protect the eyes as they develop. Once you take your newborn home, you might be wishing for those eyes to close once in a while so you can get some rest!

Your baby might be able to put a thumb in the mouth this week, although sucking hasn’t completely developed yet .

Your Body When You're 13 Weeks Pregnant

Pregnancy Symptoms at 13 Weeks

At 13 weeks pregnant, you're entering your second trimester and may notice some changes in your body and the way that you feel. For example:

• Nausea starts to fade and morning sickness lessens.
• You may have more energy as hormone levels stabilize.
• You might notice more vaginal discharge, which is normal and helps prevent infection.
• Your breasts may still be tender and might start producing an early type of breast milk called colostrum.
• As your uterus grows, you might feel sharp pains in your lower belly. While these pains are common, if the pain persists or you have any other symptoms along with the pain (such as vaginal bleeding) let your doctor know right away.
• You might be peeing less often than earlier in your pregnancy because your body is becoming more efficient in handling fluids.
• Your mood may improve, or mood swings happen less often.

Each pregnancy is different for everyone, even if you’ve been pregnant before. Always talk to your doctor if you have any questions or concerns about how you’re doing.

Important Appointments at 13 Weeks

Prenatal care, including prenatal tests, continue to be an important step for keeping you and your baby healthy. At your first prenatal appointment, your health care provider probably recommended prenatal vitamins. Taking these supplements, in addition to eating a healthy diet, ensures your baby gets needed vitamins and minerals, such as folic acid, zinc, iron, and calcium, which aid growth and development.

Ask your doctor or pharmacist about the best way to take your vitamins (such as whether they should be taken with food).

Ultrasound Appointment

If you have an ultrasound around this time, it can check how your baby is growing. Sometimes, your provider will be able to tell the sex of your baby. Other times, it’s too early to tell for sure. An ultrasound can also look for signs of potential health problems. 

Not all pregnant women will have an ultrasound at 13 weeks, but doctors do recommend an ultrasound at 18–22 weeks for all pregnancies.