For many pregnant women, the transition to the third trimester feels like an important milestone: the due date is approaching, and both the body and daily life can start to change more noticeably. But when exactly does the 3rd trimester begin, and how do you calculate it for your own pregnancy? Here’s a practical, Danish guide with clear week indications and help for planning the rest of your pregnancy.
When does the 3rd trimester of pregnancy begin (week 28)?
In Danish health information, the 3rd trimester is typically stated to start around pregnancy week 28 and last until birth. This means that when you go from week 27+6 to 28+0 (i.e., when you begin week 28), you are normally considered to be in the third trimester.
Why can there be slight differences in information?
Some sources describe trimester divisions slightly differently because pregnancy can be calculated in weeks, months, or thirds of an approximately 40-week course. In practice, however, week 28 will be the most commonly used "rule of thumb," which is also consistent in clinical material.
When do you enter the 3rd trimester - how to calculate it
The most precise way is to use your due date or the date your pregnancy was calculated from (often based on a scan).
Quick method (without a calculator)
- Find your current pregnancy week (e.g., in your app or maternity record).
- When your week changes to 28+0, you are generally in the 3rd trimester.
If you are unsure about the week indication
Contact your midwife or doctor if your dates change after a scan, or if you are unsure which calculation applies to you. It is quite normal for adjustments to be made early in pregnancy.
3rd trimester week by week - what does week 28 to birth mean in practice?
The third trimester covers the last part of pregnancy, during which the baby grows rapidly, and your body often experiences more strain in daily life. Many also find that appointments become more frequent, and there is more focus on preparing for childbirth and the time after.
Practical planning in the 3rd trimester
- Keep track of midwife appointments and any scans.
- Prepare questions continuously (symptoms, movement, sleep, concerns).
- Think of small, concrete preparations instead of doing everything at once (e.g., washing baby clothes, arranging help, transportation to the birth center).
Typical signs and changes in the 3rd trimester (and when to react)
In the third trimester, it is common to feel more heaviness, fatigue, and discomfort from your back, pelvis, or sleep. Many also experience more Braxton Hicks contractions and a greater need for breaks throughout the day.
When should you contact healthcare professionals?
Contact a midwife, doctor, or maternity ward if you experience symptoms that make you uneasy, for example, if you notice a significant change in the baby's movements, bleeding, persistent severe pain, or a sudden worsening of your condition. Always follow the guidance of your maternity unit, as they can provide specific advice based on your situation.
Due date calculator and dates - why trimester shifts can feel "fluid"
Many use a due date calculator or pregnancy app, but it is important to remember that calculations are approximate. The due date is an estimate, and birth can occur both before and after.
How to use the calculation smartly
- Use the week indication to plan (appointments, maternity leave, practical purchases).
- Use your body as a guide in daily life: slow down when you need to.
- Consult with your midwife if you have special needs or concerns at the end of your pregnancy.
Relevant products for comfort in the 3rd trimester (optional)
As the belly gets heavier in the 3rd trimester, some may benefit from extra support in daily life. An adjustable maternity support belt can relieve pressure on the abdomen and lower back during activity if it feels comfortable for you.