You're standing in the grocery store, someone asks how far along you are, and you freeze. "27 weeks," you say, because that's what the app tells you every Tuesday morning. Then comes the inevitable follow-up: "Oh, so how many months is that?" Suddenly, you’re doing mental gymnastics. Is it six months? Is it seven? Why is pregnancy math so much harder than regular math? Converting 27 weeks to months isn't just a simple division problem because the calendar is a mess of 30 and 31-day months, while your pregnancy is tracked in neat, seven-day blocks.
Honestly, it’s confusing for a reason.
If you just divide 27 by four, you get 6.75 months. But nobody says they are 6.75 months pregnant. If you go by the standard medical definition used by groups like the American College of Obstetricians and Gynecologists (ACOG), you are officially finishing up your sixth month and standing right on the doorstep of the seventh. This is a massive milestone. It is the beginning of the third trimester.
The breakdown of 27 weeks to months
Most people think a month is four weeks. It isn't. Except for February, every month is actually about 4.3 weeks long. This is where the "pregnancy brain" fog meets actual mathematical friction. When you are hit with the question of 27 weeks to months, the most accurate answer is that you are six months and three weeks pregnant. You have finished six full months. Next week, at week 28, you'll be starting month seven.
Let's look at how the medical community actually views this timeline versus how your grandmother might see it. Doctors track by weeks because fetal development happens on a day-to-day basis. A baby's lungs at 27 weeks look drastically different than they did at 24 weeks. However, the "monthly" tracker is mostly for social convenience.
You've been pregnant for about 189 days.
If you look at the lunar month calendar—which some cultures still prefer—you're actually further along. But in the standard Gregorian calendar used in the US and UK, you're in that "bridge" week. It's the transition from the relatively comfortable second trimester into the "I can't see my toes" third trimester. It’s a weird spot to be in. You aren't "huge" yet, but you definitely aren't "glowing" in that effortless way the magazines promised back in month four.
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Why the third trimester starts now
The medical consensus usually places the start of the third trimester right here, at the 27 or 28-week mark. It’s a bit of a debate among clinicians. Some say the third trimester starts at 27 weeks and 0 days; others hold out until 28 weeks.
Why does it matter?
Viability. This is the big word doctors use. According to the Mayo Clinic, a baby born at 27 weeks has a significantly higher chance of survival—exceeding 90%—thanks to modern Neonatal Intensive Care Unit (NICU) technology. While you definitely want that baby to stay put for another 13 weeks, reaching the 27 weeks to months milestone provides a massive sigh of biological relief. The nervous system is maturing. The eyes, which have been fused shut for months, are finally starting to blink.
The baby is also starting to practice breathing. They aren't breathing air, obviously. They are inhaling and exhaling amniotic fluid. It's a dress rehearsal for the big debut.
What's actually happening at 6 months and 3 weeks?
At this stage, your baby is roughly the size of a head of cauliflower. They weigh about two pounds. Their brain is growing so fast that the smooth surface is starting to develop those characteristic grooves and folds.
You’re probably feeling it, too.
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The kicks aren't just "flutters" anymore. They are distinct thumps. Sometimes it feels like a stray elbow is trying to exit through your ribcage. This is because the space inside the uterus is getting cramped. There’s less room for the baby to do full somersaults, so you get more focused, localized jabs.
- Your fundal height (the distance from your pubic bone to the top of the uterus) should be around 27 centimeters.
- You might notice "practice contractions" or Braxton Hicks.
- Sleeping through the night is likely becoming a legendary myth of the past.
- Leg cramps. Oh, the leg cramps. Usually at 3:00 AM.
Misconceptions about the 40-week timeline
People assume 40 weeks equals 10 months. It doesn't. 40 weeks is technically 9 months and about one week. This is why the 27 weeks to months calculation feels so skewed. If you tell someone you're 7 months pregnant when you hit week 28, and then tell them you're 9 months pregnant at week 36, they’re going to be very confused when you’re still pregnant at week 40.
The math only works if you stop trying to make every month exactly four weeks long.
Acknowledge the overlap. Pregnancy is 280 days. Divide that by the average month length of 30.4 days, and you get 9.2 months. You are currently 67.5% of the way through the journey.
The glucose test hurdle
Right around the time you hit 27 weeks, your OB-GYN or midwife will likely schedule the Glucose Tolerance Test (GTT). This is the "orange drink" test. It checks for gestational diabetes, a condition where pregnancy hormones interfere with how your body uses insulin.
Don't panic if you fail the one-hour screen. A lot of women do. It’s a very sensitive screen designed to catch everyone, meaning it produces a lot of "false positives" that are cleared up by the more rigorous three-hour test. According to the Cleveland Clinic, about 2% to 10% of pregnancies in the U.S. are affected by gestational diabetes, and it’s manageable with diet or medication. But yeah, the drink tastes like flat, super-sugary soda. It’s not great.
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Survival guide for the 27-week mark
You're in the home stretch, but the "stretch" part is literal. Your skin is tight. Your back hurts. Your center of gravity is shifting forward, making you feel a bit like a penguin.
Lower back pain at 27 weeks is almost universal. The hormone relaxin is loosening your joints to prepare for birth, but it’s also making your pelvis feel like a bowl of jelly.
- Invest in a pregnancy pillow. If you haven't yet, do it. The "C" or "U" shaped ones are lifesavers for supporting the bump and the hips.
- Hydrate like it's your job. Dehydration can actually trigger Braxton Hicks contractions and make those leg cramps worse.
- Check your iron levels. Many women become slightly anemic around month seven because the baby is hogging all the red blood cell resources. If you're feeling unusually exhausted (beyond the normal "I'm growing a human" tired), ask for a blood draw.
- Start the "Big Gear" shopping. At 27 weeks, you still have the energy to walk around a store and test out strollers. By 34 weeks, you’ll want to do everything from the couch.
Looking ahead to month 7 and beyond
As you move past the 27 weeks to months mark, the focus shifts from "is the baby okay?" to "is the house ready?" This is the peak nesting phase.
You’ll find yourself suddenly needing to organize the spice rack or scrub the baseboards at midnight. It’s a biological urge.
The weight gain also tends to pick up speed now. Generally, doctors look for about one pound per week in the third trimester. If you've struggled with body image, this part is tough. Just remember that a significant chunk of that weight isn't fat—it's the baby, the placenta (which weighs about a pound and a half), the extra quart of blood you've produced, and the nearly two pounds of amniotic fluid.
You are a literal life-support system.
Practical next steps for your 27th week
Instead of just counting days, use this week to tick off a few high-value tasks while you're still mobile and relatively energetic.
- Finalize your birth plan. Whether you want an unmedicated birth, an epidural the second you hit the parking lot, or a scheduled C-section, write it down. Discuss it with your provider now to ensure you're on the same page.
- Register for classes. If you haven't taken an infant CPR or breastfeeding class, sign up this week. These usually fill up fast.
- Pack a "Mini" Hospital Bag. You don't need the full suitcase yet, but having a list of what you’ll need (and maybe a spare pair of long phone chargers) ready to go provides peace of mind.
- Track the kicks. Start noticing the baby's patterns. Do they move more after you eat? Are they active at night? You don't necessarily need a "kick counter" app yet unless your doctor recommends it, but being mindful of their rhythm is a great habit.
Reaching 27 weeks is a massive achievement. You've navigated the morning sickness of the first trimester and the weird transitions of the second. Now, as you officially enter the territory of "months" that start with a seven, you’re in the final countdown. Focus on rest, keep your fluids up, and stop worrying about the exact decimal point of the math. You're almost there.