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What Is the Fourth Trimester?

Reviewed by Dan Brennan, MD on June 17, 2021

The fourth trimester is the 12 weeks following the birth of a newborn. In these first few months of your baby’s life, it’s an important time to create a bond with them. It’s also a period of adjustment as your baby adapts to life outside of the womb.

Why Is It Called the Fourth Trimester?

The first trimester of pregnancy is from 1 to 14 weeks, the second trimester is from 14 to 28 weeks, and the third trimester is from 28 weeks until your baby is born. The fourth trimester includes the first weeks after you’ve given birth. This is the time when both you and your baby adjust to life after delivery.

The term fourth trimester was coined in 2002 by pediatrician Harvey Karp, MD. He claimed that you should try to recreate the kind of environment that your baby had while still in the womb. There are several ways that you can do this.

Skin-to-skin contact. To help recreate what your baby’s life in the womb was like, you and your partner can share skin-to-skin contact with your baby. This way, your baby can feel your heartbeat and the warmth of your skin, which are both comforting and familiar to them. You can also get this contact with your baby during breastfeeding.

Swaddling and moving. While in the womb, your baby was in a small, confined space. You can recreate this sense of safety and security for them by swaddling. Studies show that babies may sleep better when swaddled. You can also get this same effect by carrying your baby in a sling close to your body.

Movement is also very comforting for your baby. Since they are used to the movement of your body from being in the womb, movement during the fourth trimester for infants is familiar to them.

What to Expect in the Fourth Trimester

The fourth trimester is an important time for newborns. Typically, they have their first pediatric checkup during the first week after they’re born. This doctor visit is important to monitor their health and development. Your baby’s pediatrician will continue to closely monitor their well-being throughout the following weeks.

In these first months after birth, your baby is just learning how to use their senses to process the world around them. They are totally dependent on you to care for them and to understand their needs. It’s during this time that your baby will likely learn how to start doing some things independently, like:

  • Making noises to communicate
  • Holding their head up without help
  • Keeping their attention on objects and follow them
  • Using their muscles
  • Smiling

Your baby has a lot of adjusting to do outside of the womb. Their brains are taking in new sensations like tastes, smells, and sounds. During this time, it’s important to follow their cues when it comes to sleeping, crying, and feeding.

In the fourth trimester, babies need 14 to 17 hours of sleep each day, even though their sleep schedule won’t be predictable. After the fourth trimester, your baby may start to sleep through the night. They will also need to be fed every 2 to 3 hours because their little body is growing so quickly.

When it comes to crying, you can try swaddling or rocking your baby to create that familiar environment for them. Other times, your baby will cry because they are hungry, need a diaper change, or simply want to be held by you.

Tips for Mom

For moms, you’ll notice that the fourth trimester is a period of great change for you, too. Before delivery, the mother’s health is monitored quite closely. After birth, the focus usually shifts from you to the health of your baby. But it’s just as important that new mothers get good postpartum care, too.

Your body is adjusting from pregnancy to healing from birth. Some common side effects that you might feel from childbirth include:

  • Changes in hormones
  • Swelling
  • Postpartum bleeding
  • A general feeling of discomfort

These effects, plus the lack of sleep, can cause you to feel stress or anxiety, or to have mood swings. It’s important to talk to your doctor about how you feel after giving birth and to not be afraid to ask for help when you need it.

To help yourself stay well during the 4th trimester, make sure you:

  • Eat a nutritious, balanced diet.
  • Try to get rest when your schedule and your baby’s schedule allow.
  • Check in with your doctor or midwife if you experience pain or feel unwell.
  • Talk to your doctor if you feel like you might have symptoms of postpartum depression.

Show Sources

SOURCES:

Harvard Health Publishing: “The fourth trimester: What you should know.”

Lifespan: “What is the Fourth Trimester?”

Pregnancy, Birth and Baby: “What is the fourth trimester?”

University of Texas Southwestern Medical Center: “The ‘fourth trimester’: Why women need health care after delivery.”

WFMC Health: “The Fourth Trimester - What to Expect and Why It’s Important.”

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