The second trimester of pregnancy spans from week 14 through week 27. It covers the middle three months and is often called the most comfortable stretch of pregnancy, as early symptoms like nausea and fatigue tend to ease while the baby undergoes rapid growth and development.
When the Second Trimester Starts and Ends
The second trimester officially begins at 14 weeks and 0 days and ends at 27 weeks and 6 days. That places it roughly at the start of month four through the end of month six. The third trimester picks up at week 28 and continues until delivery.
How Your Baby Develops
The second trimester is when your baby transforms from a small, fragile form into something that looks and moves like a newborn. Growth is fast, and nearly every system in the body matures significantly over these 14 weeks.
In the early weeks (13 to 16), bones begin to harden in the skull and limbs, red blood cells start forming in the spleen, and the scalp hair pattern takes shape. By week 16, limb movements become coordinated enough to show up clearly on ultrasound. Toenails start developing around week 17.
The middle stretch (weeks 18 to 22) brings some of the most noticeable changes. The ears stand out from the head and your baby may begin to hear sounds. The digestive system starts working. A greasy, protective coating covers the skin, and fine downy hair spreads across the entire body. The sucking reflex develops, which means thumb-sucking sometimes shows up on ultrasound images. By week 22, eyebrows and hair are visible.
In the later weeks (23 to 27), the lungs begin producing a substance that will help them inflate after birth. Your baby starts responding to familiar sounds, including your voice. The eyelids and eyelashes form, though the eyes may not open until around week 28. Fat begins building under the skin, giving it a smoother appearance. The nervous system continues maturing through the end of the trimester.
Feeling Your Baby Move
One of the biggest milestones of the second trimester is quickening, the first time you feel your baby move. This typically happens between weeks 16 and 20. If you’ve been pregnant before, you may notice it closer to 16 weeks. First-time mothers more commonly feel it around week 20. Most women describe it as bubbles popping or light tapping, and it’s easy to mistake for gas at first. Movements become stronger and more distinct as the weeks go on.
Physical Changes You May Notice
Many women feel a noticeable boost in energy during the second trimester compared to the exhaustion of the first. Nausea often fades, and sleep may come more easily for a while.
Hormone shifts increase the number of pigment-producing cells in your skin, which can cause brown, tan, or gray patches on the face, a condition sometimes called the “mask of pregnancy.” Small clusters of tiny blood vessels may appear near the skin’s surface, especially on the face and legs. These spider veins usually fade after delivery. Your belly and breasts continue growing, and you may start to feel a stretching or pulling sensation on either side of your lower abdomen as the ligaments supporting your uterus expand.
Screenings and Tests
The biggest appointment of the second trimester is the anatomy scan, an ultrasound typically done around week 20. This detailed exam checks your baby’s brain, face, heart, lungs, abdominal organs, kidneys, spine, and all twelve long bones. The sonographer measures the head circumference, the distance across the skull, the abdominal circumference, and the thigh bone length to confirm growth is on track. The hands, feet, facial features, and heart chambers are each examined individually. This is also the appointment where many parents learn the baby’s sex.
Between weeks 24 and 28, you’ll be screened for gestational diabetes with a glucose challenge test. You drink a sugary solution and have your blood drawn an hour later. A blood sugar reading below 140 mg/dL is generally considered normal. If the result comes back higher, a longer three-hour follow-up test is used to confirm or rule out gestational diabetes. The test is quick, requires no fasting for the first round, and feels like little more than drinking a very sweet beverage.
Nutrition and Weight Gain
Calorie needs increase modestly in the second trimester. Women who begin pregnancy at a higher weight typically need about 200 extra calories per day during these months, roughly the equivalent of a small snack. The focus matters more than the quantity: iron, calcium, protein, and folate all support the rapid fetal growth happening during this stage.
Total weight gain over the full pregnancy depends on your starting weight. Current guidelines recommend 25 to 35 pounds for women who begin at a normal weight, 15 to 25 pounds for those who start overweight, and 11 to 20 pounds for those who start with obesity. Most of that gain happens in the second and third trimesters.
Sleep Position
You may have heard that you need to sleep on your left side throughout pregnancy. An NIH-funded study found that sleeping on your back or either side through week 30 does not appear to increase the risk of stillbirth, reduced birth size, or high blood pressure complications. That’s reassuring if you have trouble staying on your left side or shift positions while asleep. The research did not evaluate positions beyond 30 weeks, so the guidance to favor side sleeping applies mainly to the third trimester.
Warning Signs to Watch For
Most second-trimester symptoms are normal, but a few warrant immediate attention. Vaginal bleeding heavier than light spotting can signal a problem with the placenta. Fluid leaking from the vagina could mean your water has broken early. A severe headache that won’t go away, sudden vision changes, extreme swelling in your hands or face, or trouble breathing can be signs of preeclampsia, a dangerous blood pressure condition that can develop during the second half of pregnancy.
Other red flags include severe belly pain that doesn’t let up, a fever, chest pain or a racing heart, and a noticeable slowdown or stop in your baby’s movements once you’ve been feeling them regularly. Swelling, redness, or pain in one leg could indicate a blood clot. Any of these symptoms call for prompt medical evaluation.