27 weeks pregnant: symptoms and baby development
Lungs that could breathe, and cheeks filling out.
Second trimesterMonth 65 min read
By Solesia, from public clinical guidanceUpdated
The second trimester ends this week, and it goes out the way it came in, quietly. Your baby’s lungs could, in principle, draw a breath now, and their cheeks and limbs are filling out with fat by the day, so the outline on the last scan is becoming a face. For you, the theme is sleep. Finding a position that works takes longer, the bump is in the way of the ones you liked, you are up in the night more than once, and for some people snoring starts. It is simply the load beginning to show, and a pillow between the knees helps more than you would expect.
How big is your baby at 27 weeks
About the size of a cauliflower
14.4 in long·2.3 lb
Baby development at 27 weeks
At 27 weeks your baby measures about 14.4 inches from head to heel and weighs around 2.3 pounds, roughly a head of cauliflower. The wrinkled, loose skin is filling out as fat gathers beneath it, the cheeks first, and they look more like a newborn every week.
The lungs are developed enough that they could work, with help, if they had to. The air sacs are there, the blood vessels wrap them, and surfactant is being made, though not yet in the amounts a full-term baby has. They practice breathing movements all the time, drawing fluid in and out, and hiccups, a rhythmic tapping that lasts a few minutes, are part of that practice.
The brain is growing quickly, folding to fit more surface into the skull, and it now runs sleep cycles that include the rapid eye movement of dreaming. They open and close their eyes, respond to light and to your voice, and have a sense of taste. All the organs are formed; what remains for the third trimester is growing, maturing and putting on weight, about half a pound a week from now.
Your body at 27 weeks
Sleep is harder from about now, and that is expected. The bump makes turning over a project, the bladder wakes you, the baby is often busiest when you lie down, and heartburn and cramps have their say. Side-lying with a pillow behind your back, one between your knees and one under the bump is the arrangement to get used to this week, because from 28 the advice is to fall asleep on your side.
Snoring can start in pregnancy, even in people who never did. The lining of the nose and throat is swollen by extra blood and hormones, and the weight you have gained narrows the airway a little. Sleeping on your side, a raised pillow and a humidifier all help. Snoring that comes with gasping, or with being very sleepy in the day, is worth mentioning at a visit, because it can be treated.
Your stomach is being squeezed from below and progesterone keeps the gut slow, so bloating, constipation and heartburn cluster around now. Small meals, fiber, water and walking cover the first two; for heartburn, staying upright after eating and skipping late, heavy or spicy meals does the rest. Your provider can suggest an antacid that is fine in pregnancy if it keeps you awake.
Common pregnancy symptoms at 27 weeks
- Trouble sleeping. A big bump, a busy baby, a full bladder. Side-lying with pillows behind, between and under.
- Snoring. Swollen nose and throat lining. Sleep on your side, raise the pillow, run a humidifier.
- Bloating and constipation. A squeezed stomach and a slow gut. Small meals, fiber, water, and a daily walk.
- Heartburn. The valve at the top of the stomach has relaxed. Upright after eating; nothing heavy late.
- Leg cramps. Calves seizing at night. Straighten the leg and pull your toes up; stretch before bed.
- Hemorrhoids. Pressure on pelvic veins plus constipation. Fiber and water, no straining; a cream if sore.
- Swollen feet. Fluid settling through the day. Feet up in the evening, comfortable shoes.
When to call your provider at 27 weeks
Two things are worth a same-day call at any point in pregnancy: bleeding that is more than spotting, and pain that is severe or does not ease. From the second trimester, add fluid leaking and any change in your baby’s usual pattern of movement. You do not need to be sure something is wrong to call; that is what the number is for.
What to do at 27 weeks
- Tdap vaccine. The window is 27 to 36 weeks, and this week is the front of it. The shot passes whooping cough protection to your baby for their first two months. It is given in every pregnancy.
- Glucose screening deadline. If it has not been done, it needs to be by 28 weeks. Many practices combine it with the 28-week visit and blood work.
- The 28-week visit ahead. Next week’s visit often includes a blood count for anemia and, if your blood type is Rh-negative, a RhoGAM shot. After 28, visits move to every two weeks.
- Side-sleeping from 28. Practice this week: go to sleep on your side, with a pillow behind you. Waking on your back is fine; just turn over.
Common questions at 27 weeks
Is 27 weeks the third trimester?
Not quite. Week 27 is the last week of the second trimester; the third trimester begins at 28 and runs until the birth. A few things change at 28: visits every two weeks, side-sleeping, and a blood count for anemia.
Is the Tdap shot safe at 27 weeks?
Yes. It is recommended between 27 and 36 weeks in every pregnancy, and it has a long safety record in pregnancy. A sore arm for a day or two is the usual effect. The antibodies you make cross the placenta and protect your baby from whooping cough until their own vaccines start at two months.
Why should I sleep on my side from 28 weeks?
Lying flat on your back lets the weight of the uterus press on the large vein that returns blood to your heart, which can reduce the blood reaching the placenta. The advice is about how you fall asleep, not how you wake; if you find yourself on your back in the night, turn onto your side and go back to sleep. Either side is fine.
Can I still fly at 27 weeks?
Yes, and for many people this is the last easy week for it. Airlines let you fly well into the third trimester, but many ask for a note from your provider from 28 weeks and set a cutoff around 36. Drink water, walk the aisle every hour, and wear the seat belt under the bump.
Written from public clinical guidance, including NHS: Week 27, ACOG: How your baby grows, ACOG: Changes in your body, ACOG: The Tdap vaccine and pregnancy, ACOG: Gestational diabetes, NHS: Indigestion and heartburn and NHS: Tiredness. This page is general information, not medical advice, and does not replace your provider.