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Pregnancy at week 13

Your baby

Your baby is now fully formed. They are moving about vigorously in your uterus and they can move their arms and legs, suck their thumb and form a fist.

Your baby's testes or ovaries are now fully developed, and a penis or clitoris is still growing. That means by the time you have your 20 week ultrasound, your doctor might be able to see the sex of your baby and share this with you if you are wanting to know.

Your baby's organs, including their liver and pancreas, are starting to function and their vocal cords are beginning to develop. By now they also have soft hair on their eyebrows and head.

Your body

At 13 weeks, you have officially entered the second trimester of pregnancy. Your bump might be showing and you may feel the ligaments stretching in your tummy and groin.

You may also notice more visible veins, especially in your breasts. You may have food cravings or food aversions, or have heartburn, indigestion or constipation.

You may also notice skin changes including dark patches on your face or neck, called 'melasma' , or develop a dark line from your belly button down to your pubic area, called linea nigra. These are both caused by the hormonal changes in your body and will usually resolve on their own after pregnancy.

Things to remember

The chances of having a miscarriage decrease significantly once you enter the second trimester. Many people therefore decide to share the news of their pregnancy at this time. Chat with your partner or support person about how you want to do this and be prepared in case people don't react in the way you hoped.

It's worth thinking early about how you will manage life with a baby. If you haven't already, now is a good time to find out more about your parental rights and entitlements.

If you haven't already had prenatal screening or diagnostic tests and are wanting to, speak to your doctor or midwife about what options are available to you in the second trimester.

Resources and support

Speak to your doctor, midwife or obstetrician if you have questions about your pregnancy.

Pregnancy, Birth and Baby also has more information on:

NEXT WEEK...YOUR PREGNANCY AT WEEK 14 — Learn about your pregnancy journey and what is happening to you and your baby.

Speak to a maternal child health nurse

Call Pregnancy, Birth and Baby to speak to a maternal child health nurse on 1800 882 436 or video call. Available 7am to midnight (AET), 7 days a week.

Last reviewed: August 2023