Seven months pregnant is approximately 28 to 31 weeks of pregnancy. The exact count depends on how you define a “month,” since calendar months vary between 28 and 31 days, but most providers consider the seventh month to span weeks 28 through 31. This marks the beginning of the third trimester, which officially starts at 28 weeks and 0 days.
Why Weeks and Months Don’t Line Up Neatly
Pregnancy is tracked in 40 weeks, not nine calendar months. Because most months are longer than four weeks, the math never divides evenly. A lunar month is exactly four weeks (28 days), but February is the only calendar month that short. The rest are 30 or 31 days, adding an extra two or three days each time. Over nine months, those extra days add up to roughly an additional month of pregnancy, which is why “nine months” actually equals 40 weeks.
Doctors and midwives count from the first day of your last menstrual period, not conception. That means you’re technically about two weeks “pregnant” before fertilization even happens. This is why week counts can feel ahead of what you’d expect. When your provider says you’re 28 weeks, you’ve been pregnant for about six and a half calendar months, but you’re entering what’s commonly called month seven.
What’s Happening at 28 Weeks
At the 28-week mark, the average baby measures about 25 centimeters (9.8 inches) from crown to rump and weighs roughly 1,000 grams (2.2 pounds). That’s about the size of a large eggplant. From here, your baby enters a stretch of rapid weight gain that continues through delivery.
Several important developments are underway during month seven. The lungs begin producing surfactant, a substance the baby will need to breathe air after birth. The lungs are functional but still immature, which is one reason every additional week in the womb matters. By week 27, the baby can open and close its eyes and blink for the first time. The body is also building up fat reserves, which fill out the skin, reduce wrinkling, and will help regulate temperature after birth.
Third Trimester Symptoms to Expect
Crossing into the third trimester brings a new set of physical changes. Some are mild annoyances, others can genuinely disrupt your day. Here’s what’s common starting around month seven:
- Braxton Hicks contractions. These are mild tightenings across your belly that come and go without a pattern. They’re more likely in the afternoon or evening, after physical activity, or after sex. They tend to get stronger and more frequent as you approach your due date. If you’re having more than six in an hour and they’re getting steadily stronger, contact your provider.
- Back pain. Pregnancy hormones loosen the connective tissue in your pelvis, and the growing uterus stretches your abdominal muscles. Together, these shifts put extra strain on your lower back.
- Heartburn and constipation. Hormones slow your digestion while your expanding uterus presses on your intestines. Both problems tend to get worse as the third trimester progresses.
Prenatal Tests Around This Time
The 28-week window is a busy one for checkups. If you haven’t already had a glucose screening test, it’s typically done between 24 and 28 weeks. This test checks for gestational diabetes by measuring how your body processes sugar. It usually involves drinking a sweet glucose solution and having your blood drawn an hour later.
Your provider may also review your Rh factor results from earlier in pregnancy. If your blood is Rh-negative and the baby’s is Rh-positive, you’ll receive an injection around 28 weeks to prevent your immune system from reacting to the baby’s blood cells. From this point on, prenatal visits generally shift from monthly to every two weeks.
Sleep and Comfort in Month Seven
Side sleeping becomes increasingly important as you enter the third trimester. Lying on your back puts the weight of your uterus on a major vein that returns blood from your lower body to your heart, which can reduce blood flow to both you and the baby. The left side is considered ideal because it maximizes blood flow to the baby and improves kidney function, but either side is fine.
If side sleeping feels uncomfortable, placing a pillow between your knees and another under your belly can create enough of a tilt to relieve pressure. A pillow behind your back helps keep you from rolling over during the night. Many people find a full-length body pillow easier than juggling multiple smaller ones.
Weeks-to-Months Quick Reference
Since the conversion comes up throughout pregnancy, here’s a rough guide for the third trimester:
- Month 7: Weeks 28 to 31
- Month 8: Weeks 32 to 35
- Month 9: Weeks 36 to 40
These ranges aren’t exact because months and weeks don’t divide evenly, but they match how most providers and pregnancy resources group the weeks. When precision matters, stick with the week count your provider uses. “I’m 30 weeks” is always more accurate than “I’m seven months.”