Mild Prematurity: Symptoms, Causes, and Treatments

What is mild prematurity?

Mild or borderline prematurity refers to babies born between the 34th and 36th weeks of gestation, also known as late preterm infants. These births occur close to the end of the full gestational period, which typically ranges from the 37th to the 41st week. Although late preterm babies may resemble those born at full term, they are still undergoing development in several areas. Therefore, they are at a higher risk of developing health issues and should not be treated the same as full-term newborns.

Among the main causes of this condition are premature rupture of the membrane surrounding the baby and a pregnancy complication called preeclampsia, which is characterized by high blood pressure (hypertension). Additionally, in twin pregnancies, the likelihood of babies being born between the 34th and 36th weeks and six days of gestation (late preterm) is five times higher than in pregnancies with a single baby.

Symptoms

Some of the most common symptoms in babies born with mild prematurity include:

Yellowish skin or eyes (jaundice): in the first days of life, the liver is unable to clear the blood of a yellow substance called bilirubin, resulting in a yellowish appearance of the skin and eyes
Mild difficulty breastfeeding: babies may feed slowly or, in some cases, may not yet be able to feed properly. This difficulty is due to a lack of coordination in sucking, swallowing, and breathing. These reflexes are still developing. Stomach emptying and intestinal movements are also slower, which can lead to feeding intolerance
Low blood sugar levels (hypoglycemia): insufficient milk intake due to feeding difficulties can increase the risk of hypoglycemia in the baby
Longer sleep periods: they usually sleep more than full-term babies
Low body temperature: mildly premature newborns do not have enough body fat to maintain a normal temperature (36.5 °C), which may result in a drop in body temperature
Different developmental pace: premature babies may reach certain developmental milestones later than those born after the 37th week of gestation. For example, they may take longer to roll over, speak, or hold objects with their hands

Learn about the different types of prematurity and their symptoms, which may vary depending on the baby’s gestational age at birth — that is, the duration of the pregnancy, calculated from the first day of the mother’s last menstrual period.

Diagnosis

The diagnosis of mild prematurity is based on the baby’s gestational age, determined by the number of weeks since the mother’s last menstrual period. In addition, the healthcare professional (neonatologist) evaluates the baby’s health, development, and signs of maturity. These include:

Weight
Size
Head circumference measurement
Physical criteria, such as nipple formation, skin texture, ear shape, and folds in the roof of the mouth (palate)
Muscle flexibility and reflexes (neuromuscular)

Blood tests and imaging exams are also important for assessing the newborn’s health. They help identify possible infections, monitor nutrient levels, and detect anemia that may affect development. These tests also check the condition of internal organs such as the heart, lungs, and brain.

Treatment

Treatment for babies with mild prematurity depends on their individual needs. They may not require care in the Neonatal Intensive Care Unit (NICU) if born after 35 weeks of gestation. However, some may need special care, which includes:

Treatment for yellowish skin and eyes (jaundice): exposure to special light (phototherapy), commonly used to treat the condition and eliminate bilirubin from the body.
Incubator stay: the baby may be placed in an incubator, a medical device that helps maintain the proper body temperature (36.5 °C). It has a transparent structure that allows visualization of the baby and circular openings on the sides for hand access, enabling care without compromising the internal environment.
Use of neonatal ventilator: the newborn may experience respiratory problems (respiratory distress syndrome). In such cases, assistance with a device that helps push air into and out of the lungs may be recommended. Supplemental oxygen may also be used to support breathing.
Specialized nutrition: if the premature baby has difficulty feeding orally, a thin tube (feeding tube) is often used to deliver food directly to the stomach or intestines, or through a vein (intravenous nutrition), allowing the baby to receive essential nutrients.

Continuous medical monitoring is essential to support the treatment of any health conditions that may arise.

Prevention

The prevention of mild prematurity begins with prenatal care. This includes frequent visits to the obstetrician during pregnancy. Medical appointments should occur regularly:

Up to the 28th week: monthly, with a minimum interval of 4 weeks between visits
Between the 28th and 36th week: every two weeks
After the 36th week: weekly

Other measures also contribute to preventing premature birth, such as:

Engaging in light physical activity during pregnancy, such as walking, for two and a half hours per week, if there are no medical restrictions
Avoiding smoking, drug use, or alcohol consumption
Monitoring weight with guidance from a healthcare professional
Managing maternal conditions such as diabetes and anemia
Reducing stress