The development of premature babies at 33 - 36 weeks

This is an automatically translated article.

The article is professionally consulted by Resident Doctor, Master Dang Thi Ngoan - Department of Pediatrics - Neonatology - Vinmec Ha Long International Hospital


Newborns between 33 and 36 weeks of gestation are still classified as premature babies, however the prognosis for babies born at this time is very positive and it is perfectly possible to take care of them to help them grow. healthy.

1. Causes of Premature Birth

Women who have a healthy pregnancy may still be at risk for preterm delivery, while other women who are at risk for complications may be able to carry a full-term pregnancy. In case there are some problems during pregnancy affecting the health of mother, fetus or both, the pregnancy needs to be terminated at that time, these are called medically indicated causes of preterm birth. Some typical examples are preeclampsia, growth restriction...
The most common causes of preterm birth include.
Multiple pregnancy , carrying more than one baby at a time (twins or more) Uterine bleeding Stress Infections in the uterus or from another part of the body Women with bleeding during pregnancy can also cause preterm birth. Women with a history of prior preterm birth, as well as those with pregnancies less than 2 years apart, were more likely to have a preterm birth. Having a short cervix or a history of surgery on the uterus or cervix may also increase the risk of preterm birth.
Some lifestyle habits can also cause babies to be born at 33 - 34 weeks or earlier. Smoking during pregnancy is one of the most common causes of preterm birth and can lead to decreased fetal lung capacity, as well as lower-than-average birth weight. Chronic stress in pregnant women is also another risk factor.

2. Can an infant at 33-36 weeks survive?

The closer babies are born to their due date, the better their chances of survival. By the 36th week, the baby's body is completely formed and the baby is almost ready to survive in the outside environment. At 34 weeks, many of your baby's body systems are not mature enough, especially the lungs. The lungs do not reach full formation until about 36 weeks.
Neonatal intensive care units (NICUs) at most hospitals are well equipped to help babies breathe on their own if they are born at 34 weeks. Many hospitals are staffed. are well trained to support late premature babies and treat various health problems. In fact, babies born between 31 and 34 weeks usually have a 95% survival rate depending on other health conditions.

3. The development of babies born at 33 - 36 weeks

3.1. Development of babies born at 33-34 weeks
Premature babies between 33 and 34 weeks are also known as “medium preterm babies”. Weighing between 1800 - 2200g at birth and nearly 50cm long, these babies are roughly the same size as a full-term baby. Although they are getting older, babies at 33 and 34 weeks are still immature and may need to stay in the NICU for several weeks.
Premature babies are almost fully developed at 33 and 34 weeks. The baby's bones are fully formed, fingernails are as long as the fingertips, and in boys, the testicles descend into the scrotum. However, the respiratory system is not fully developed until the last weeks of pregnancy and antibodies only begin to be passed from mother to baby in the last months – so the health of the baby's immune system remains compromised. partly affected.
At 33 and 34 weeks, most premature babies will have a fairly short NICU stay, and may experience only a few complications. They may need short-term respiratory support, but it may take longer for babies to learn to suck. The suck-swallow-breath reflex in babies during this time is often not well coordinated and these babies may not be strong enough to absorb enough nutrients to grow and gain weight.
During this time, you also need to pay attention to your baby's cues that indicate overstimulation from the environment, such as hiccups, sneezing, crying or stretching. Protecting your child's sleep time is very important during this time.

3.2. Infant development at 35-36 weeks
Premature babies born at 35-36 weeks are called "late preterm babies". These babies are about 50cm long and usually weigh between 2200 and 2600g. Babies at 35 and 36 weeks look like full-term babies, but they're still classified as premature and may have some problems with being born prematurely.
The child has reached full height, is gaining weight rapidly, has fingernails that are fingertip lengths and is full of fingerprints.
Although they look like full-term babies, babies at 35 and 36 weeks are still premature babies. Their lungs aren't fully developed for the next few weeks, and they may not have enough fat to stay warm or strong enough to breastfeed or bottle-feed effectively. It is important to continue to protect the child's sleep and time in the NICU until the child is eligible for discharge from the NICU.
Newborns at this stage can move more smoothly and easily bend their arms and legs. Babies can also move their head from side to side, and their muscle tone is stronger. Children will have much less apnea.
The baby's states are very clear - deep sleep, light sleep, sleepy, quiet and awake, awake and fussy or crying. The infant's waking states are still quite brief, but they are getting longer and more frequent. Children may have longer contact time with their environment and may now turn their heads or close their eyes when they feel full.
Children are more likely to respond to sounds and noises from the outside environment. You can even see how a child will react when he or she hears the familiar voice of a parent. The baby may still not cry much. But as they near full term, babies will cry more often to signal to you what they want. Babies can usually start breastfeeding around this time. Your baby may still be sensitive to touch and hold, but talking to him will help him relax over time.

4. Possible complications in infants 33 – 36 weeks

Although clinicians tend to focus on obvious manifestations of problems in infants born less than 34 weeks of age, late preterm infants are also at risk for many of the same disorders as premature infants at a younger age.
Compared with term infants, late preterm infants have longer hospital stays and higher rates of recurrence and diagnosed disorders. Most complications related to dysfunction of immature organ systems are similar to those seen in infants of younger age, but of lesser severity than complications in neonates. young. However, some complications of preterm birth (eg, necrotizing enterocolitis, retinopathy of prematurity, bronchopulmonary dysplasia, intraventricular hemorrhage) are uncommon in late preterm infants. In most cases, complications are easily treated and leave no sequelae
More common complications in late preterm infants include:
Central nervous system: Stages of apnea Digestive: Poor suckling due to delayed maturation of sucking and swallowing mechanisms (main cause of prolonged and/or recurrent hospital stays) Hyperbilirubinemia : Caused by immature liver metabolism and/or increased intestinal reabsorption of bilirubin (eg, poor feeding causes decreased intestinal motility) Hypoglycaemia: Caused by low glycogen stores Temperature instability: 50% of neonates have hypothermia in many to varying degrees (due to increased surface area to volume ratio, reduced adipose tissue, and inefficient thermogenesis from brown fat)

5. Taking care of babies at 33 - 36 weeks of gestation

Because infants 33 – 36 are still at risk for complications of preterm birth. Therefore, the child is quite likely to be treated in the NICU. This depends on the baby's birth weight and their overall health. Babies born to mothers who smoke, drink alcohol or abuse drugs are more likely to be born prematurely and have more health problems from birth.
Initial treatment for a premature, low birth weight baby begins with care for the baby in the hospital NICU. Babies born prematurely may have weakened immune systems and are more susceptible to illness than full-term babies. Breastfed babies receive antibodies from breast milk and can more easily avoid illness. While exclusive breastfeeding is the mother's choice, many hospitals will have lactation consultants to help mothers best care for their babies.
After the child is discharged from the hospital, it is important to feed the child regularly to help him gain weight. Take your child to see a pediatrician to help monitor his growth and development, keeping in mind the developmental milestones he or she needs to reach. If your baby has long-term complications from being born prematurely, you can talk to a specialist about how best to treat and manage this condition.


To prevent diseases that babies often get, parents should pay attention to nutrition to improve children's resistance. At the same time, add supporting foods containing lysine, essential micro-minerals and vitamins such as zinc, chromium, selenium, B vitamins,... snacks and less digestive problems.
Parents can learn more:
Why do you need to supplement Lysine for your baby?
The role of zinc - Guidelines for reasonable zinc supplementation
Please visit the website Vinmec.com regularly and update useful information to take care of your baby and family.

References: raisingchildren.net.au, verywellfamily.com