The second trimester runs from week 14 through week 27 of pregnancy, lasting 14 weeks total. That translates roughly to months four, five, and six. Many people call this the most comfortable stretch of pregnancy because first-trimester nausea typically fades while the physical demands of the third trimester haven’t yet kicked in.
How the Weeks Break Down
Your first trimester covers weeks 1 through 13. The second trimester picks up at week 14 and continues through the end of week 27. The third trimester then starts at week 28 and lasts until delivery, typically around week 40. Some medical sources define the second trimester as ending at week 26 rather than 27, which is why you may see slight differences depending on where you look. The variation comes down to how different organizations round the math on dividing 40 weeks into three periods.
Regardless of whether your provider counts the cutoff at 26 or 27 weeks, the practical window is the same: you’re in your second trimester for roughly three and a half months.
What You’ll Feel During These Weeks
One of the hallmark moments of the second trimester is feeling your baby move for the first time. If this is your first pregnancy, expect to notice those flutters around 20 weeks. If you’ve been pregnant before, you may pick up on movement as early as 16 weeks. These early sensations are subtle, often described as bubbles or a light tapping.
Round ligament pain is another common second-trimester experience. The ligaments that support your uterus stretch and widen as your belly grows, and sudden movements like standing up quickly or coughing can cause a sharp, stabbing pain on one or both sides of your lower abdomen. This is most common between weeks 14 and 27 and, while uncomfortable, is a normal part of accommodating your growing uterus.
Sleep may also start to change. As your uterus gets larger, lying on your back can put pressure on the major vein that returns blood from your lower body to your heart. Side sleeping, particularly on your left side, helps keep blood flowing efficiently. Many people find a pillow between the knees or under the belly makes this position more comfortable.
How Your Baby Develops
The second trimester is when your baby starts looking and acting much more like a newborn. By month four, eyelids, eyebrows, eyelashes, nails, and hair have formed. The baby can stretch, make facial expressions, and even suck its thumb. By the last few weeks of the second trimester, your baby can hear your voice.
Growth accelerates dramatically during these weeks. At the start of the second trimester, the fetus is roughly the size of a lemon. By the end, it weighs about two pounds and is over a foot long. Organs are maturing, fat is beginning to accumulate under the skin, and the lungs are developing the structures they’ll eventually need to breathe air.
Key Appointments and Tests
Two major medical milestones fall in the second trimester. The first is the anatomy scan, a detailed ultrasound performed between 18 and 22 weeks. During this appointment, a sonographer measures and photographs the baby’s heart, brain, spine, kidneys, limbs, and facial features. They also check the position of the placenta, measure amniotic fluid levels, record the fetal heart rate, and examine blood flow through the umbilical cord. This is often the ultrasound where parents learn the baby’s sex, if they choose to.
The second is gestational diabetes screening, which typically happens between 24 and 28 weeks. You’ll drink a sugary solution and have your blood drawn an hour later. A blood sugar reading below 140 mg/dL is generally considered a passing result. If your number comes back higher, your provider will schedule a longer follow-up test to confirm or rule out gestational diabetes. If you have risk factors, your provider may screen you before 24 weeks.
Weight Gain and Nutrition
Starting around week 14, steady weight gain becomes more important. For people who began pregnancy at a healthy weight, the general guideline is about one pound per week through the rest of pregnancy. That rate applies to both the second and third trimesters.
Calorie needs increase modestly. Most normal-weight pregnant people need about 2,200 calories per day during the second trimester, which works out to roughly 300 extra calories compared to pre-pregnancy intake. That’s the equivalent of a banana with peanut butter and a glass of milk. The emphasis is less on eating more and more on eating well: iron-rich foods to support increased blood volume, calcium for bone development, and protein for fetal growth.