Week 15 of Pregnancy: Your Baby Is the Size of an Apple

TL;DR

• Your baby is about 10.1 cm — the size of an apple.
• Baby can sense light through closed eyelids.
• You may notice increased appetite and a growing bump.
• Focus on a balanced diet with plenty of protein and fiber.

Your Baby This Week

At 10.1 cm, your baby is now the size of an apple — and growing quickly. One of the most remarkable developments this week is that your baby can now sense light. Even though the eyelids are still fused shut, the eyes are sensitive enough to detect brightness. If you were to shine a flashlight at your belly, your baby might actually turn away from the glow.

Your baby's skeleton is continuing to develop, transitioning from soft cartilage to hardened bone. This process, called ossification, will continue throughout pregnancy and even after birth. The bones in the legs are now growing longer than the arms, and the body proportions are becoming more baby-like.

Taste buds are forming on your baby's tongue, and the muscles throughout the body are getting stronger. Your little one is moving around quite a bit — flexing arms, curling toes, and making fists — even though you probably can't feel it yet. These movements help the muscles and joints develop properly.

The ears are almost in their final position on the sides of the head, having migrated up from the neck. While your baby can't hear clearly yet, the structures that will eventually process sound are actively developing.

Your Body This Week

Week 15 often brings a welcome return of appetite. If the first trimester left you surviving on crackers and ginger ale, you may finally feel ready to eat real meals again. Your body needs about 340 extra calories per day during the second trimester — roughly an extra snack or small meal.

Your bump may be more noticeable this week, though it varies widely from person to person. Some people look unmistakably pregnant at 15 weeks, while others can still keep the news private. Either way is completely normal.

You might notice changes in your skin — some people develop a darker line running down the center of the belly called the linea nigra. Freckles and moles may darken, and some people notice patches of darker skin on the face (called melasma or the "mask of pregnancy"). These changes are driven by increased melanin production and usually fade after birth.

Round ligament pain might make its first appearance around now. As your uterus grows, the ligaments that support it stretch, and this can cause sudden, sharp pains on one or both sides of your lower belly — especially when you move quickly, sneeze, or change positions.

Common Questions at Week 15

How much weight should I have gained by now?

Every pregnancy is different, but a general guideline is 1-5 pounds during the first trimester and about 1 pound per week during the second trimester. Your provider will track your weight gain and let you know if anything needs adjusting.

Why am I getting nosebleeds?

Increased blood volume and hormonal changes make the blood vessels in your nose more fragile. Nosebleeds and nasal congestion are common in the second trimester. Using a humidifier and saline spray can help.

Can I sleep on my back?

At 15 weeks, sleeping on your back is still generally fine. As your uterus gets heavier later in pregnancy, side sleeping becomes recommended to keep weight off the vena cava. Start getting comfortable on your side now — a body pillow can help.

This Week's Tip

Continue eating a balanced diet with plenty of protein and fiber. Protein supports your baby's rapid growth, while fiber helps combat the constipation that plagues so many pregnant people. Good sources include lean meats, beans, lentils, whole grains, fruits, and vegetables. If prenatal vitamins are making you nauseated, talk to your provider about switching brands or taking them with food at a different time of day.

Sources

• American College of Obstetricians and Gynecologists (ACOG). How Your Fetus Grows During Pregnancy.
• Mayo Clinic. Fetal Development: The 2nd Trimester.

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