Week 25 brings a baby who is starting to look distinctly like a person. Fat is gradually filling in under the skin, giving those once-translucent features more definition. And this week, the hair on your baby's head has acquired its actual color and texture. The lanugo — the soft, downy hair covering the body — is still present, but the hair that will eventually peek out from under that newborn hat has its own identity now.
You're firmly in the second half of pregnancy. The third trimester is just a few weeks away.
Use our Due Date Calculator to see exactly where you stand.
Your Baby This Week
Size: Cauliflower — about 34.6 cm (head to toe)
Weight: About 660 grams
Your baby is growing steadily, and several important milestones are happening this week:
- Hair has color and texture. The melanocytes responsible for pigment have been active for several weeks, and by now the hair follicles on the scalp contain hair with the actual color and texture your baby will be born with. Some babies are born with a full head of hair; others arrive practically bald — both are completely normal.
- The spine is forming its structure. Thirty-three rings of bone, 150 joints, and around 1,000 ligaments make up the developing spine. These are all forming and hardening now.
- The nostrils begin to open. Until now, the nostrils have been plugged. This week they begin to open, allowing the baby to practice breathing motions — inhaling and exhaling amniotic fluid to exercise the respiratory muscles and lungs.
- Blood vessel development in the lungs. The pulmonary vasculature is developing in preparation for the moment of birth, when the lungs need to receive blood and oxygenate it for the first time.
- The hands are becoming more coordinated. Grasping motions are increasingly purposeful, and the baby may be putting their hands to their face or mouth.
- Fat accumulation continues. This process will accelerate significantly in the third trimester, giving the newborn the rounded, chubby appearance we associate with healthy babies.
Your Body This Week
- Symphysis pubis dysfunction (SPD). The hormone relaxin, which loosens the ligaments of the pelvis in preparation for birth, can sometimes cause the pubic joint to become unstable and painful. Pain in the front of the pelvis, inner thighs, and hips — especially when walking, climbing stairs, or turning over in bed — may indicate SPD. A referral to a physiotherapist is often very helpful.
- Hemorrhoids. Increased blood volume, constipation, and pressure from the uterus on the rectal veins can cause hemorrhoids. These are swollen veins in the rectal area that can cause itching, pain, or bleeding. Staying hydrated, eating fiber-rich foods, and avoiding long periods of sitting or standing helps.
- Stretch marks. If they haven't appeared yet, they often emerge around this point as the belly grows more rapidly. Keeping skin moisturized helps with discomfort, though the marks themselves are largely determined by genetics and the speed of growth.
- Braxton Hicks contractions are likely more frequent and perhaps more noticeable. They're still irregular and painless. Distinguishing them from real contractions: Braxton Hicks usually stop with movement or hydration; real contractions get stronger and more regular over time.
- Increased hunger. The second trimester appetite often peaks around now. Eating small, nutrient-dense meals throughout the day is more comfortable than large ones as stomach space decreases.
Tips for Week 25
1. Prioritize iron-rich meals. Blood volume has increased by nearly 50% during pregnancy (Mayo Clinic), and your baby's iron stores are building. Low iron is the most common nutritional deficiency in pregnancy. If you're feeling unusually tired or breathless, ask your provider to check your iron levels.
2. Practice good posture actively. The growing belly shifts your center of gravity forward, which pulls the lower back into an exaggerated curve. Conscious effort to engage your core, keep your shoulders back, and avoid locking your knees when standing helps prevent and manage back pain.
3. Consider prenatal massage. Therapeutic pregnancy massage from a qualified practitioner can meaningfully reduce back pain, leg cramps, and stress. Make sure your therapist is trained in prenatal massage and uses positioning that's safe for pregnancy.
4. Plan for maternity leave. If you haven't already, now is the time to have the formal conversation with your employer about leave dates, coverage plans, and your intended return. Earlier is better — it gives everyone time to plan.
5. Do the kick count. Around this week, some providers recommend beginning informal fetal movement awareness. You don't need a formal app yet, but paying attention to your baby's movement pattern — when they're most active, how it feels — gives you a useful baseline for later in pregnancy.
When to Call Your Doctor
- Pelvic pain that limits your mobility. SPD (see above) is manageable with physiotherapy, but it needs to be assessed to rule out other causes.
- Hemorrhoid bleeding. A small amount of bright red blood on toilet paper after a bowel movement is usually hemorrhoids, but any rectal bleeding in pregnancy should be mentioned to your provider to rule out other causes.
- Signs of preterm labor: contractions that are regular, pelvic pressure, low back pain that comes and goes, or a change in vaginal discharge before 37 weeks
- Decreased fetal movement compared to your established normal pattern
- Sudden or severe swelling, headache, or vision changes — evaluate for preeclampsia
Related Tools & Articles
- Due Date Calculator — Calculate your estimated due date
- Pregnancy Week-by-Week Overview — the full 40-week guide
- Milestone Tracker — track your baby's development
- Hospital Bag Checklist — start planning ahead