Your second trimester lasts 14 weeks, running from week 14 through the end of week 27. That puts it right in the middle third of a full-term pregnancy, and it’s often called the most comfortable stretch of the entire 40 weeks.
Exact Week-by-Week Boundaries
The second trimester officially spans from 14 weeks and 0 days to 27 weeks and 6 days of pregnancy. It covers months four, five, six, and the very beginning of month seven. If you’re counting from the start of your last menstrual period (which is how pregnancy weeks are calculated), you enter the second trimester at the start of week 14 and transition into the third trimester once you hit week 28.
A common point of confusion is whether week 13 falls in the first or second trimester. Some sources round slightly differently, but the clinical standard places the cutoff at the start of week 14. If you’re at 13 weeks and 6 days, you’re technically still in the first trimester.
Why It’s Called the “Honeymoon” Period
For many people, the second trimester brings noticeable relief from nausea, fatigue, and the general fog of early pregnancy. Energy levels tend to bounce back, appetite stabilizes, and you’re not yet large enough for the physical discomforts that come later. That window of relative ease is one reason doctors consider weeks 14 through 28 the safest and most practical time for travel.
That said, the second trimester has its own set of physical changes. You may notice Braxton Hicks contractions, which feel like a mild tightening across your belly that comes and goes. They’re more common in the afternoon or evening, after activity, or after sex. They’re not a sign of labor.
Skin changes are also common during these weeks. Hormonal shifts increase the number of pigment-producing cells in your skin, which can cause brown or gray patches on your face (melasma) and a dark vertical line down your belly (linea nigra). Stretch marks may appear on your belly, breasts, buttocks, or thighs, and small spider veins can show up on your face and legs.
What Your Baby Is Doing in There
The second trimester is described as the period of rapid growth and development. Your baby enters it roughly the size of a lemon and exits it weighing around two pounds.
Around week 18, the ears start to stand out from the head and your baby may begin hearing sounds for the first time. By week 20, the halfway mark of pregnancy, many people feel their baby move for the first time. This sensation, called quickening, often starts as a light fluttering that’s easy to mistake for gas. First-time parents sometimes don’t notice it until a few weeks later, while those who’ve been pregnant before may recognize it earlier.
By the final weeks of the second trimester, your baby is approaching the earliest edge of viability outside the womb. The period from 20 to 25 weeks is considered “periviable,” meaning survival is possible but far from certain. Babies born at 23 weeks survive roughly 23 to 27 percent of the time. At 24 weeks, that rate rises to 42 to 59 percent, and at 25 weeks it reaches 67 to 76 percent. These numbers underscore just how much critical development is packed into the final weeks of the second trimester.
Key Tests and Appointments
Two major screenings happen during the second trimester, and knowing when to expect them helps you plan.
The anatomy scan (sometimes called the 20-week ultrasound) is typically scheduled between weeks 18 and 22. This is the most thorough ultrasound of your pregnancy. A technician takes detailed measurements and images of your baby’s heart, brain, spine, kidneys, limbs, face, and lungs. They also check the position of the placenta, measure amniotic fluid levels, examine blood flow through the umbilical cord, and look at your cervix. For many families, this is also the appointment where you can learn the baby’s sex.
The glucose screening test comes later, usually between weeks 24 and 28. You’ll drink a sugary solution and have your blood drawn to check how well your body processes sugar. If your blood sugar comes back higher than expected, you’ll take a longer follow-up test to determine whether you have gestational diabetes. This is a routine screening for all pregnancies, not a sign that something is wrong.
If your blood type is Rh-negative, you’ll also receive an injection between weeks 26 and 28 that prevents your immune system from producing antibodies against your baby’s blood cells. This is a standard precaution when there’s a potential mismatch between your blood type and your baby’s.
Travel and Activity During These Weeks
Weeks 14 through 28 are considered the best window for travel during pregnancy. Morning sickness has typically faded, your energy is back, and you’re still mobile enough to move comfortably. After 28 weeks, travel carries more risk and becomes logistically harder.
If you’re flying, check your airline’s policies before booking. Some carriers require a note from your doctor stating your due date, and many have cutoff dates for pregnant passengers. On long flights or car rides, the main concern is blood clots from sitting too long. Getting up to walk every hour or two and staying hydrated are the simplest ways to reduce that risk.
Weight Gain to Expect
Most of your pregnancy weight gain happens during the second and third trimesters. Total recommended gain for the entire pregnancy depends on your starting weight. For people who begin pregnancy at a normal BMI, the general target is 25 to 35 pounds total. For those starting overweight (BMI 25 to 29.9), the range drops to 15 to 25 pounds. For those starting in the obese range, the recommendation is 11 to 20 pounds. Twin pregnancies have higher targets across all categories, ranging from 25 to 54 pounds depending on pre-pregnancy BMI.
During the second trimester specifically, most people gain roughly a pound per week, though this varies widely from person to person and week to week. Sudden or rapid weight gain can sometimes signal fluid retention, so your provider will track your weight at each visit.