The Third Trimester: A Month-by-Month Timeline

By Kerry Weiss
Reviewed by Alyssa Quimby, M.D.
November 01, 2022

For the text version of this infographic, read on:

The Third-Trimester Timeline

The third trimester begins at week 28 of pregnancy, which is the start of the 7th month. It’s the final countdown to your baby’s birth.

Month 7

Digestive problems—like bloating, heartburn, and indigestion—can begin. It can help to:

  • Avoid greasy, spicy, and rich foods
  • Eat smaller, more frequent meals
  • Cut back on caffeine

You may also feel clumsier and less coordinated.

Back and hip pain tends to get worse, and you may have numbness and swelling in your hands, especially in the morning.

“Pregnancy brain”—or issues with memory, concentration, and absentmindedness—can start (and may persist after the baby is born).

Your brain isn’t the only thing that’s tired. Fatigue is common at this point. Use a pregnancy pillow to get as comfortable as possible in bed.

That little one is growing! By the end of the month, your baby will be about 14 inches long and can weigh up to 4 pounds.

Month 8

Back pain, varicose veins, hemorrhoids, and stress incontinence can appear.

The good news? Once you reach week 30, you’re 75% of the way there.

Now your doctor will likely start seeing you once every 2 weeks. Talk to your doctor about your birth plan, if you haven’t yet.

Let the nesting begin—you may feel an urge to clean and organize to prepare for the baby's arrival.

By the end of the month, your little one will measure around 18 inches long and weigh up to 5 pounds.

Month 9

You’ve reached the homestretch!

Your doctor will want to start seeing you once a week until the baby arrives.

Each pang you experience may leave you wondering whether your baby’s coming soon. Early signs of labor include:

  • Feeling like the baby is dropping low (called lightening)
  • Contractions similar to menstrual cramps
  • Loss of the mucus plug

Don’t be fooled by false labor. Know the signs of true labor contractions:

  • They come at regular intervals.
  • They get closer over time.
  • They become stronger steadily.
  • They persist whether resting or moving.
  • They often start in your back.

Call your doctor or go to the hospital if:

  • Your water breaks.
  • Contractions happen every 5 minutes for 1 hour, with each lasting 1 minute. This is known as 5-1-1.

These are signs of labor.

Know your birth options. If you haven’t taken a birth class, now is the time!

Across all live births in the United States in 2020:

  • 68% were vaginal deliveries
  • 32% were cesarean sections, or C-sections

About 14% of those vaginal deliveries were a VBAC (vaginal birth after cesarean)

Meanwhile, the baby is measuring up to 19 inches long and weighing around 6 1/2 pounds at the end of the 9th month.

Countdown to Baby

A full-term pregnancy lasts about 280 days, or 40 weeks.

Most babies aren’t born on their due dates.

In 2017, this is when U.S. babies arrived:

  • 10% before 37 weeks
  • 26% weeks 37 to 38
  • 57% weeks 39 to 40
  • 6% week 41
  • Less than 1% at 42 weeks or later

The third trimester ends in the most exciting way: with your baby’s birth!


American College of Obstetricians and Gynecologists

American Pregnancy Association. Nesting During Pregnancy. Accessed October 6, 2022.

Centers for Disease Control and Prevention. (Last reviewed May 2022) Births—Method of Delivery.

Cleveland Clinic

Family Doctor. (Last updated August 2022) Sleep and Pregnancy.

Johns Hopkins Medicine. Get a Good Night’s Sleep During Pregnancy. Accessed October 6, 2022.

March of Dimes

Mayo Clinic

National Health Service (UK)

National Institutes of Health

New York State Department of Health. (Revised April 2021) Why Is 40 Weeks So Important?

Osterman, M. J. K. et al. (2022) Births: Final Data for 2020. National Vital Statistics Reports, Vol. 70, No. 17. National Center for Health Statistics.

Planned Parenthood. Pregnancy Month by Month. Accessed October 6, 2022.