Second Trimester Week by Week — What to Expect (Weeks 14-27)

Welcome to the second trimester — for many women, this is when pregnancy starts to feel enjoyable. By week 14, your baby is about the size of a navel orange (roughly 3.5 inches) and is making facial expressions like squinting and frowning as facial muscles develop. The body is now growing faster than the head, bringing proportions closer to newborn size.

At week 15, the baby is forming a fine, downy hair called lanugo that covers the entire body to help regulate temperature. The skeleton is beginning to harden from cartilage to bone, and if you could peek inside, you might catch the baby sucking a thumb. By week 16, the baby is about the size of an avocado (4.5 inches), and the circulatory and urinary systems are fully functional.

For you, the biggest change is usually a welcome wave of energy and reduced nausea. Your uterus is now about the size of a small melon and has risen out of the pelvis, which means less pressure on your bladder (temporarily — it comes back in the third trimester). Your bump may start showing, especially in snug clothing. Some women begin to feel tiny flutters — though first-time mothers usually don't feel definitive movement until weeks 18-22.

Common new symptoms include round ligament pain (sharp or achy sensations on the sides of your lower belly as ligaments stretch), nasal congestion from increased blood volume, and the beginning of that 'pregnancy glow' as blood flow to the skin increases.

Weeks 17-20 are milestone-packed. By week 17, the baby's skeleton is transitioning from soft cartilage to bone, and fat stores are beginning to form under the skin. Sweat glands are developing, and the baby weighs about 5 ounces. At week 18, the baby can now hear sounds — your heartbeat, your voice, and digestive noises are the soundtrack of their world. Many parents begin talking or playing music to their bump.

Week 19 brings the development of vernix caseosa, a waxy, cheese-like coating that protects the baby's skin from the amniotic fluid. The baby is developing distinct sleep-wake cycles, and you may notice patterns of activity and rest.

Week 20 is a major milestone — you're halfway through pregnancy. The anatomy scan (also called the mid-pregnancy ultrasound or level-2 ultrasound) typically happens between weeks 18-22. This detailed examination checks the baby's brain, heart chambers and valves, spine, kidneys, stomach, limbs, and facial structures. It also evaluates the placenta location, amniotic fluid levels, and umbilical cord. If you want to know the sex, this is usually when it can be reliably determined.

By now, you've almost certainly felt quickening — those first definitive baby movements that feel like flutters, bubbles, or gentle taps. The baby is about 6.5 inches long and weighs about 10 ounces. Your uterus is now at the level of your navel, and weight gain of 8-12 pounds so far is typical.

During weeks 21-24, the baby's growth accelerates dramatically. By week 21, the baby is about the size of a large banana and is swallowing amniotic fluid regularly — both practicing for feeding and absorbing nutrients. Taste buds are formed, and studies suggest babies may already show preferences for certain flavors based on what the mother eats.

At week 22, the baby's eyes have formed (though the irises still lack pigment), and eyebrows and eyelashes are visible. The lungs are developing rapidly but are not yet mature enough to function outside the womb. The baby's grip is getting stronger, and they're regularly grabbing the umbilical cord.

Week 23-24 marks a critical milestone: viability. This is the point at which a baby, if born prematurely, has a chance of surviving with intensive medical care. At 24 weeks, survival rates in advanced NICUs are approximately 60-70%, though these babies face a long and difficult road. The lungs are beginning to produce surfactant — the substance that keeps air sacs open — but won't produce adequate amounts until closer to 34-36 weeks.

For you, the baby's movements are now unmistakable and increasingly strong. Partners can often feel kicks from the outside. Common second-trimester symptoms at this stage include Braxton Hicks contractions (irregular, painless tightening of the uterus), leg cramps (especially at night), mild swelling in the ankles and feet, stretch marks as your belly grows, and a dark line (linea nigra) forming down the center of your abdomen. Your provider may order a glucose screening test around week 24-28 to check for gestational diabetes.

The second trimester includes several important screening opportunities. If you didn't complete first-trimester screening, the quad screen (maternal serum screening) can be done between weeks 15-22. This blood test measures four substances — AFP, hCG, estriol, and inhibin A — to assess risk for Down syndrome, trisomy 18, and neural tube defects like spina bifida.

Amniocentesis, if recommended or requested, is typically performed between weeks 15-20. A thin needle guided by ultrasound withdraws a small sample of amniotic fluid for genetic analysis. It's a diagnostic test (not a screening), providing definitive answers about chromosomal conditions with more than 99% accuracy. The procedure carries a small miscarriage risk of approximately 0.1-0.3%.

The anatomy ultrasound (weeks 18-22) is the most comprehensive imaging of the pregnancy. It evaluates fetal growth, organ development, placental position, and amniotic fluid volume. If the placenta is found to be low-lying (covering or near the cervix), your provider will monitor it — most placenta previa cases resolve on their own as the uterus grows.

Between weeks 24-28, the glucose challenge test screens for gestational diabetes. You'll drink a sugary solution and have your blood drawn one hour later. If results are elevated (typically above 130-140 mg/dL), you'll take the longer three-hour glucose tolerance test for confirmation. Gestational diabetes affects 6-9% of pregnancies and is manageable with diet, exercise, and sometimes medication.

Routine prenatal visits in the second trimester typically happen every four weeks and include blood pressure checks, weight monitoring, fundal height measurement, and listening to the baby's heartbeat.

The second trimester brings a mix of welcome and challenging physical changes. On the positive side, most women experience a significant energy boost, reduced nausea, thicker and shinier hair (thanks to hormones slowing normal hair shedding), and that often-mentioned 'pregnancy glow' from increased blood flow and oil production in the skin.

However, new symptoms emerge as your body accommodates your growing baby. Round ligament pain — sharp or stabbing sensations on one or both sides of the lower belly — is very common and happens as the ligaments supporting your uterus stretch. It's typically triggered by sudden movements like standing up quickly, coughing, or rolling over in bed.

Back pain begins for many women as the growing uterus shifts your center of gravity forward, straining your lower back muscles. Good posture, supportive shoes, and prenatal-safe exercises like swimming and prenatal yoga can help significantly.

Skin changes are widespread: the linea nigra (a dark vertical line from navel to pubic bone), melasma (darkening patches on the face, sometimes called the 'mask of pregnancy'), and stretch marks on the belly, breasts, and thighs. These are driven by hormones and increased melanin production.

Other common symptoms include Braxton Hicks contractions (your uterus practicing for labor — irregular and usually painless), leg cramps especially at night, mild swelling in the ankles and feet by the end of the day, nasal congestion and occasional nosebleeds from increased blood volume, and hemorrhoids from increased pressure and constipation. While most of these are normal, always report any symptom that seems sudden or severe to your provider.

Feeling your baby move for the first time — called quickening — is one of pregnancy's most exciting milestones. Most first-time mothers feel definitive movement between weeks 18-22, while women who've been pregnant before may notice it as early as weeks 14-16 (because they know what to look for).

Early movements feel subtle — like bubbles popping, a goldfish swimming, gentle flutters, or even gas. Over the following weeks, these flutters become unmistakable kicks, rolls, punches, and hiccups. By weeks 24-28, movements are typically strong enough for your partner to feel from the outside, and you'll start to notice patterns — many babies are most active in the evening when you're lying still.

Babies have sleep-wake cycles of about 20-40 minutes, so periods of quiet are completely normal. They may also respond to external stimuli — a cold drink, a loud noise, or gentle pressure on your belly can sometimes trigger a kick.

Your provider will likely recommend starting kick counts around week 28. The general guideline is to feel at least 10 distinct movements within 2 hours during a time when the baby is usually active. Most babies will reach 10 movements in well under an hour.

Contact your provider if you notice a significant decrease in movement compared to your baby's normal pattern, you can't reach 10 movements in 2 hours despite trying, or there's a sudden change from active to very quiet. Reduced fetal movement can sometimes signal that the baby is in distress, and it's always better to get checked and be reassured than to wait.