Week 15

Your baby measures about 4 inches from crown to rump. Navel orange territory.

The chest is the headline this week. Your baby's diaphragm contracts, amniotic fluid flows in, and the muscles push it back out. Over and over. These aren't occasional twitches. They're patterned and rhythmic, and they'll continue for the rest of the pregnancy.

Nobody really tells you about fetal breathing practice.

It sounds strange. Breathing without air. But every contraction strengthens the diaphragm and intercostal muscles your baby will use for that first breath at birth.

Scalp hair follicles are forming right now. The pattern they're setting determines where hair will grow thick and where it won't. Whether your baby shows up needing a trim or barely wearing peach fuzz is largely genetic. Visible hair won't appear for several more weeks, but the blueprint is down.

Your baby's body proportions are shifting too. Arms and legs are now roughly equal in length, after weeks where arms led the way. Movements are more coordinated. Kicks, stretches, rolls. Constant. You probably won't feel any of it for a few more weeks, but on ultrasound it looks like a tiny tumbling class.

The face is settling. Ears are moving into position on the sides of the head. Eyes are shifting toward the front. Skin is still thin and translucent, but everything is starting to look less like an alien and more like a small person.

Probably not a cold.

Pregnancy rhinitis is congestion caused by your expanding blood volume swelling the membranes inside your nose. A 2022 literature review found it affects roughly 10 to 30% of pregnant people, with estimates commonly landing around 20%.

It shows up most often in the second trimester and can stick around until delivery.

Two weeks postpartum, it's usually gone.

Here's what helps. Saline nasal spray. A humidifier at night. Sleeping with your head slightly elevated. A 2025 review confirmed that these non-pharmacologic strategies are the recommended first-line approach. Don't reach for decongestants unless your provider specifically approves them. Some are not recommended during pregnancy, particularly in the first trimester.

Beyond your nose, your uterus is large enough now that you can feel it if you press gently below your belly button. Weight gain is probably picking up. ACOG suggests roughly a pound per week during the second and third trimesters for someone who started at a normal BMI, though that varies a lot. Your provider is tracking this.

You might also notice more vaginal discharge than usual. Clear or white with a mild smell? Normal. Color changes, strong odor, or itching? Call your provider.

One practical thing to check off this week: sign up for a childbirth education class. The popular ones fill up. The typical window is weeks 28 to 32. Get your name on a list now so you're not scrambling in the third trimester.