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Late preterm baby: What you need to know

Late Preterm Baby

What you need to know

Early babies

Most pregnancies last about 40 weeks. Babies born between 37 and 42 weeks of pregnancy are called “full term.” Babies born between 34 and 36 full weeks of pregnancy are called “late preterm” babies. Your baby may look and act like a baby born on its due date, but they are not fully mature and may have trouble in many ways. The list below gives some of the reasons your baby needs extra care and attention.

Brain growth and development

At 35 to 37 weeks in your pregnancy, your baby’s brain is only 75 to 80% developed and needs to grow more. They might have trouble timing their sucking, swallowing, and breathing or keeping their body temperature normal. Your baby might not be able to respond to people, noises, and activities in the same way that a full-term baby does. Too much stimulation may stress your baby. This stimulation may happen from things that you think are routine such as talking, rocking, a noisy room, or some types of music. Your baby may tell you they're stressed by spreading their fingers into “a stop” (palm out and flat) or putting their hand in front of their face. They may cry more, and you may have trouble settling them. Because their brain is growing, your baby may sleep a lot and not be as alert as a baby born at full term.

Lung development

When a baby is born early, their lungs may not be fully developed. They might have some problems with their breathing and it might be too fast or too slow. Your baby’s bed should be a firm surface, without blankets, comforters, pillows, or stuffed animals. Always place your baby on the back for sleep to prevent Sudden Infant Death Syndrome (SIDS).

Sleepiness and problems with feeding

Babies begin to store fat in the last few weeks of pregnancy. A baby uses these fat stores for energy to eat and to stay warm. Since your baby was born early, they have less fat stores, so it’s important that they feed every 3 hours. You may need to wake them and keep them awake while you’re feeding them. Good feeding builds your baby's fat stores and helps their brain develop.

Your late preterm baby may be very sleepy. Wake your baby to feed every 3 hours, if your baby doesn’t wake on their own. The hospital, public health nurses, or your midwife can teach you how to help your baby stay awake and have a good feed. Your doctor will tell you when you can let your baby sleep longer than 3 hours.

If you’re breastfeeding, you may pump or hand express milk after your baby is done feeding. This will help with your breastmilk supply. The more milk taken from the breast, the more milk you will make. This expressed breastmilk can be fed back to your baby. If you are formula feeding, choose a formula with iron and omega 3.

Most babies lose a little weight after birth. Because late preterm babies have trouble feeding, your baby may lose more weight, but they should be back to their birth weight by 2 weeks of age. Your baby should have at least 4 heavy wet diapers and 2 to 4 bowel movements (poops) every day. If they're formula feeding, your baby should have 4 heavy wet diapers and at least 1 bowel movement (poop) a day. You’ll know your baby is feeding well if they're gaining weight.

Low blood sugar

Because your baby has a small amount of fat (energy stores), it’s hard for your baby to keep their blood sugar at normal levels. Feeding often can help.

Body temperature

Late preterm babies can have trouble keeping their body temperature normal because their brains are not fully developed and they have less body fat. Take your baby’s temperature in the armpit. A normal temperature is between 36.3ºC and 37.5ºC. If your baby needs help keeping their temperature normal, putting your baby on your bare chest (skin to skin) with a blanket covering you both may help. Keep your baby away from drafts. A good rule is to dress your baby in one more layer than you’re wearing. If your baby’s temperature is low or high, it may be a sign that they're not well.


A baby born early has a less mature liver and is more likely to have jaundice than a baby born at full term. Jaundice can lead to serious problems with the brain if it isn’t treated. Signs of jaundice are: yellowing of the skin, yellowing of the whites of the eyes, sleepiness, and poor feeding. Make sure you tell your baby’s doctor if you see any of these signs. A blood test can tell if your baby has jaundice. Your baby will be checked for jaundice before they leave the hospital. Your baby should be seen by a public health nurse, midwife, or doctor within 24 to 48 hours of being at home. Feeding your baby at least every 3 hours helps to prevent jaundice.

Immune system

The immune system helps the body fight infection. In the last weeks of pregnancy, proteins that help immunity move from the mother to the baby. A late preterm baby may be born before this happens. It’s especially important to breastfeed a late preterm baby because breastmilk can help your baby develop immunity. Try to give as much breastmilk as possible.

Signs that your baby may have an infection are: a high fever of greater than 37.5ºC, a low temperature of less than 36.3°C, trouble breathing, poor feeding, or trouble waking up.

You can help protect your baby from infections by asking everyone to wash their hands before touching or holding your baby. Limit visitors and outings when your baby is very young. During fall and winter, everyone in your house should get an influenza (flu) shot.

Skin to skin

Holding your baby next to your body (skin to skin) has many benefits. It helps keep your baby’s temperature normal. It also helps your baby to have good oxygen levels, and heart and breathing rates. Babies who are held skin to skin cry less. Mothers who hold their baby skin to skin have better milk production. It’s important that you stay awake during breastfeeding or skin-to-skin time so that your baby doesn’t slip off your chest and fall. Try chewing gum to stay awake.

Call 911 anytime you think your baby may need emergency care. For example, if your baby has trouble breathing.

Call your doctor, midwife, or public health nurse, or seek immediate medical care if:

  • you’re concerned with your baby’s temperature (less than 36.3ºC or over 37.5ºC)
  • you think your baby’s skin is getting more yellow
  • your baby seems very sleepy, isn’t eating or nursing well, or isn’t acting as normal
  • you’re having problems feeding your baby
  • you have any concerns about how many wet and dirty diapers you baby is having

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For 24/7 nurse advice and general health information call Health Link at 811.

Current as of: October 21, 2022

Author: Maternal, Newborn, Child and Youth Strategic Clinical Network, Alberta Health Services

This material is not a substitute for the advice of a qualified health professional. This material is intended for general information only and is provided on an "as is", "where is" basis. Although reasonable efforts were made to confirm the accuracy of the information, Alberta Health Services does not make any representation or warranty, express, implied or statutory, as to the accuracy, reliability, completeness, applicability or fitness for a particular purpose of such information. Alberta Health Services expressly disclaims all liability for the use of these materials, and for any claims, actions, demands or suits arising from such use.