13 Weeks Pregnant: Welcome to the Second Trimester

Welcome to week 13—you’ve officially entered the second trimester! This is a major milestone in your pregnancy journey. Many women describe the second trimester as the most enjoyable part of pregnancy: morning sickness is typically fading, energy is returning, and your baby bump may be starting to show. Your baby is now about the size of a peach and is developing rapidly. Let’s explore what’s happening this exciting week.

Baby Development at 13 Weeks

Your baby is now approximately 2.9 inches long from crown to rump—about the size of a peach—and weighs about 0.8 ounces. Development is proceeding at an amazing pace as organs and systems continue to mature.

Your baby’s vocal cords are forming this week, though your baby won’t use them until after birth. The intestines, which had been growing in the umbilical cord, have fully moved into the abdomen. Your baby’s pancreas is beginning to produce insulin, and the liver is making bile.

Your baby’s bones are hardening, particularly in the skull and long bones. The skeleton, which started as soft cartilage, is now ossifying (turning into bone). This process will continue throughout pregnancy and even after birth.

Fingerprints are now fully unique. Your baby’s head, which was previously about half the body length, is now closer to one-third—body proportions are becoming more balanced. Your baby can make complex facial expressions, including squinting and frowning. For more about the second trimester, see our second trimester guide.

Your Body This Week

Welcome to the second trimester! Many women experience a noticeable shift this week. Morning sickness is fading or gone for most, energy levels are climbing, and you may feel more like yourself than you have in weeks.

Your uterus is now large enough to feel above the pubic bone. You may be developing a visible baby bump, especially if this isn’t your first pregnancy. Your waistline is expanding, and regular pants may no longer be comfortable.

Breast changes continue—your breasts may start producing colostrum (early milk) this early, though most women don’t notice it until later. Your breasts have been growing significantly and may have increased by one or two cup sizes already.

Many women notice increased libido during the second trimester as nausea fades, energy returns, and blood flow to the pelvic area increases. Unless your doctor has advised otherwise, sexual activity is safe throughout pregnancy.

Common Symptoms at 13 Weeks

Reduced Nausea: For many women, week 13 brings significant relief from morning sickness. hCG levels are declining, which is the primary driver of improvement.

Increased Energy: The fatigue of the first trimester is starting to lift. Take advantage of this renewed energy to prepare for your baby’s arrival.

Visible Veins: You may notice more visible veins on your breasts, abdomen, and legs as blood volume continues to increase.

Round Ligament Pain: Sharp pains on the sides of your lower abdomen may increase as your uterus grows. These are caused by stretching ligaments and are normal.

Nasal Congestion: Pregnancy rhinitis (stuffiness caused by increased blood flow to mucous membranes) is common in the second trimester. A humidifier and saline nasal spray can help.

What to Do This Week

Celebrate reaching the second trimester! This is a genuine milestone—miscarriage risk has dropped significantly, and many of the most uncomfortable early symptoms are fading.

Start thinking about prenatal classes. Research options in your area, including childbirth preparation, infant CPR, breastfeeding, and newborn care classes. Popular classes can fill up fast.

Begin pregnancy exercises if you haven’t already. The second trimester is an ideal time to establish an exercise routine. Pregnancy-safe exercises like walking, swimming, and prenatal yoga support your physical and mental health.

Monitor your weight gain. Now that nausea is fading and appetite is returning, be mindful of healthy weight gain during pregnancy. Focus on nutrient-dense foods and balanced meals.

Continue taking your prenatal vitamins. Even though the critical neural tube closure period has passed, prenatal vitamins remain important for supporting your baby’s ongoing development. See our prenatal vitamin guide.

Nutrition Spotlight: Fiber and Hydration

As your appetite returns, constipation may remain a challenge. Focusing on fiber and hydration can make a significant difference in digestive comfort.

Fiber: Aim for 25-30 grams of fiber daily from whole grains, fruits, vegetables, legumes, and nuts. Increase fiber gradually to avoid gas and bloating. High-fiber foods also provide essential vitamins and minerals for your baby’s development.

Hydration: Drink at least 8-10 glasses of water daily. Proper hydration supports amniotic fluid production, nutrient transport, and helps prevent constipation, urinary tract infections, and preterm contractions. For comprehensive nutrition guidance, visit our pregnancy nutrition guide.

When to Call Your Doctor

Contact your healthcare provider if you experience:

• Vaginal bleeding or spotting
• Severe abdominal pain or cramping
• Fever over 100.4°F
• Severe headaches with visual changes
• Sudden severe swelling of face, hands, or feet
• Persistent decrease in pregnancy symptoms accompanied by bleeding

See our when to call your doctor guide for complete information.

Frequently Asked Questions