Premature baby reasons

Premature birth - Symptoms and causes

Overview

A premature birth is a birth that takes place more than three weeks before the baby's estimated due date. In other words, a premature birth is one that occurs before the start of the 37th week of pregnancy.

Premature babies, especially those born very early, often have complicated medical problems. Typically, complications of prematurity vary. But the earlier your baby is born, the higher the risk of complications.

Depending on how early a baby is born, he or she may be:

Late preterm, born between 34 and 36 completed weeks of pregnancy
Moderately preterm, born between 32 and 34 weeks of pregnancy
Very preterm, born at less than 32 weeks of pregnancy
Extremely preterm, born at or before 25 weeks of pregnancy

Most premature births occur in the late preterm stage.

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Symptoms

Your baby may have very mild symptoms of premature birth, or may have more-obvious complications.

Some signs of prematurity include the following:

Small size, with a disproportionately large head
Sharper looking, less rounded features than a full-term baby's features, due to a lack of fat stores
Fine hair (lanugo) covering much of the body
Low body temperature, especially immediately after birth in the delivery room, due to a lack of stored body fat
Labored breathing or respiratory distress
Lack of reflexes for sucking and swallowing, leading to feeding difficulties

The following tables show the median birth weight, length and head circumference of premature babies at different gestational ages for each sex.

Weight, length and head circumference by gestational age for boys
Gestational age	Weight	Length	Head circumference
40 weeks	7 lbs. , 15 oz. (3.6 kg)	20 in. (51 cm)	13.8 in. (35 cm)
35 weeks	5 lbs., 8 oz. (2.5 kg)	18.1 in. (46 cm)	12.6 in. (32 cm)
32 weeks	3 lbs., 15.5 oz. (1.8 kg)	16.5 in. (42 cm)	11.6 in. (29.5 cm)
28 weeks	2 lbs., 6.8 oz. (1.1 kg)	14.4 in. (36.5 cm)	10.2 in. (26 cm)
24 weeks	1 lb., 6.9 oz. (0.65 kg)	12.2 in. (31 cm)	8.7 in. (22 cm)

Weight, length and head circumference by gestational age for girls
Gestational age	Weight	Length	Head circumference
40 weeks	7 lbs. , 7.9 oz. (3.4 kg)	20 in. (51 cm)	13.8 in. (35 cm)
35 weeks	5 lbs., 4.7 oz. (2.4 kg)	17.7 in. (45 cm)	12.4 in. (31.5 cm)
32 weeks	3 lbs., 12 oz. (1.7 kg)	16.5 in. (42 cm)	11.4 in. (29 cm)
28 weeks	2 lbs., 3.3 oz. (1.0 kg)	14.1 in. (36 cm)	9.8 in. (25 cm)
24 weeks	1 lb., 5.2 oz. (0.60 kg)	12.6 in. (32 cm)	8.3 in. (21 cm)

Special care

If you deliver a preterm baby, your baby will likely need a longer hospital stay in a special nursery unit at the hospital. Depending on how much care your baby requires, he or she may be admitted to an intermediate care nursery or the neonatal intensive care unit (NICU). Doctors and a specialized team with training in taking care of preterm babies will be available to help care for your baby. Don't hesitate to ask questions.

Your baby may need extra help feeding, and adapting immediately after delivery. Your health care team can help you understand what is needed and what your baby's care plan will be.

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Risk factors

Often, the specific cause of premature birth isn't clear. However, there are known risk factors of premature delivery, including:

Having a previous premature birth
Pregnancy with twins, triplets or other multiples
An interval of less than six months between pregnancies
Conceiving through in vitro fertilization
Problems with the uterus, cervix or placenta
Smoking cigarettes or using illicit drugs
Some infections, particularly of the amniotic fluid and lower genital tract
Some chronic conditions, such as high blood pressure and diabetes
Being underweight or overweight before pregnancy
Stressful life events, such as the death of a loved one or domestic violence
Multiple miscarriages or abortions
Physical injury or trauma

For unknown reasons, black women are more likely to experience premature birth than are women of other races. But premature birth can happen to anyone. In fact, many women who have a premature birth have no known risk factors.

Complications

While not all premature babies experience complications, being born too early can cause short-term and long-term health problems. Generally, the earlier a baby is born, the higher the risk of complications. Birth weight plays an important role, too.

Some problems may be apparent at birth, while others may not develop until later.

Short-term complications

In the first weeks, the complications of premature birth may include:

Breathing problems. A premature baby may have trouble breathing due to an immature respiratory system. If the baby's lungs lack surfactant — a substance that allows the lungs to expand — he or she may develop respiratory distress syndrome because the lungs can't expand and contract normally.

Premature babies may also develop a lung disorder known as bronchopulmonary dysplasia. In addition, some preterm babies may experience prolonged pauses in their breathing, known as apnea.
Heart problems. The most common heart problems premature babies experience are patent ductus arteriosus (PDA) and low blood pressure (hypotension). PDA is a persistent opening between the aorta and pulmonary artery. While this heart defect often closes on its own, left untreated it can lead to a heart murmur, heart failure as well as other complications. Low blood pressure may require adjustments in intravenous fluids, medicines and sometimes blood transfusions.
Brain problems. The earlier a baby is born, the greater the risk of bleeding in the brain, known as an intraventricular hemorrhage. Most hemorrhages are mild and resolve with little short-term impact. But some babies may have larger brain bleeding that causes permanent brain injury.
Temperature control problems. Premature babies can lose body heat rapidly. They don't have the stored body fat of a full-term infant, and they can't generate enough heat to counteract what's lost through the surface of their bodies. If body temperature dips too low, an abnormally low core body temperature (hypothermia) can result.

Hypothermia in a premature baby can lead to breathing problems and low blood sugar levels. In addition, a premature infant may use up all of the energy gained from feedings just to stay warm. That's why smaller premature infants require additional heat from a warmer or an incubator until they're larger and able to maintain body temperature without assistance.
Gastrointestinal problems. Premature infants are more likely to have immature gastrointestinal systems, resulting in complications such as necrotizing enterocolitis (NEC). This potentially serious condition, in which the cells lining the bowel wall are injured, can occur in premature babies after they start feeding. Premature babies who receive only breast milk have a much lower risk of developing NEC.
Blood problems. Premature babies are at risk of blood problems such as anemia and newborn jaundice. Anemia is a common condition in which the body doesn't have enough red blood cells. While all newborns experience a slow drop in red blood cell count during the first months of life, the decrease may be greater in premature babies.

Newborn jaundice is a yellow discoloration in a baby's skin and eyes that occurs because the baby's blood contains excess bilirubin, a yellow-colored substance, from the liver or red blood cells. While there are many causes of jaundice, it is more common in preterm babies.
Metabolism problems. Premature babies often have problems with their metabolism. Some premature babies may develop an abnormally low level of blood sugar (hypoglycemia). This can happen because premature infants typically have smaller stores of stored glucose than do full-term babies. Premature babies also have more difficulty converting their stored glucose into more-usable, active forms of glucose.
Immune system problems. An underdeveloped immune system, common in premature babies, can lead to a higher risk of infection. Infection in a premature baby can quickly spread to the bloodstream, causing sepsis, an infection that spreads to the bloodstream.

Long-term complications

In the long term, premature birth may lead to the following complications:

Cerebral palsy. Cerebral palsy is a disorder of movement, muscle tone or posture that can be caused by infection, inadequate blood flow or injury to a newborn's developing brain either early during pregnancy or while the baby is still young and immature.
Impaired learning. Premature babies are more likely to lag behind their full-term counterparts on various developmental milestones. Upon school age, a child who was born prematurely might be more likely to have learning disabilities.
Vision problems. Premature infants may develop retinopathy of prematurity, a disease that occurs when blood vessels swell and overgrow in the light-sensitive layer of nerves at the back of the eye (retina). Sometimes the abnormal retinal vessels gradually scar the retina, pulling it out of position. When the retina is pulled away from the back of the eye, it's called retinal detachment, a condition that, if undetected, can impair vision and cause blindness.
Hearing problems. Premature babies are at increased risk of some degree of hearing loss. All babies will have their hearing checked before going home.
Dental problems. Premature infants who have been critically ill are at increased risk of developing dental problems, such as delayed tooth eruption, tooth discoloration and improperly aligned teeth.
Behavioral and psychological problems. Children who experienced premature birth may be more likely than full-term infants to have certain behavioral or psychological problems, as well as developmental delays.
Chronic health issues. Premature babies are more likely to have chronic health issues — some of which may require hospital care — than are full-term infants. Infections, asthma and feeding problems are more likely to develop or persist. Premature infants are also at increased risk of sudden infant death syndrome (SIDS).

Prevention

Although the exact cause of preterm birth is often unknown, there are some things that can be done to help women — especially those who have an increased risk — to reduce their risk of preterm birth, including:

Progesterone supplements. Women who have a history of preterm birth, a short cervix or both factors may be able to reduce the risk of preterm birth with progesterone supplementation.
Cervical cerclage. This is a surgical procedure performed during pregnancy in women with a short cervix, or a history of cervical shortening that resulted in a preterm birth.

During this procedure, the cervix is stitched closed with strong sutures that may provide extra support to the uterus. The sutures are removed when it's time to deliver the baby. Ask your doctor if you need to avoid vigorous activity during the remainder of your pregnancy.

By Mayo Clinic Staff

Associated Procedures

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Why Are Babies Born Early? (for Parents)

Reviewed by: Thinh Phu Nguyen, MD

Fetal Medicine at Nemours Children's Health

en español ¿Por qué algunos bebés nacen antes de tiempo?

Most babies are born healthy at or near their due date. Sometimes, though, babies are born early and might have health problems.

Why Are Some Babies Born Early?

Babies born before 37 weeks are premature. A premature birth is more likely to happen when a mother has a health problem — like diabetes — or does harmful things during her pregnancy, like smoke or drink. If she lives with a lot of stress, that also can make her baby be born too early.

Many things can cause a baby to be born early or with health problems. Some of these things can be controlled, but others can't.

Here's what you can do to have a healthy pregnancy.

How Can I Stay Healthy During Pregnancy?

During pregnancy, help your baby grow strong and healthy. Be sure to:

Start prenatal care as soon as you think you're pregnant. Prenatal care is the health care that you get during pregnancy. All pregnant women should see a health care professional as soon as they think they're pregnant, and should plan regular prenatal visits throughout pregnancy.
Get health problems treated. It's best to have any health problems (like diabetes, depression, or high blood pressure) under control before becoming pregnant. But if you don't, talk to your doctor right away about a treatment plan.
Eat a healthy diet. It's important to eat a variety of healthy foods before and during pregnancy. Take a prenatal vitamin to be sure you're getting enough folic acid, iron, and other important nutrients.
Gain the right amount of weight. How much weight you should gain depends on how much you weighed before you were pregnant. Most women who are at a healthy weight should gain about 25 to 35 pounds during pregnancy. Overweight women should probably gain less.
Don't smoke, drink alcohol, or take illegal drugs. Staying away from tobacco, alcohol, and drugs can help you and your baby avoid many serious health problems, like fetal alcohol syndrome and neonatal abstinence syndrome (NAS). If you do any of these things, get help to quit.
Wait at least 12 months between pregnancies. Increasing the time between pregnancies may lower the chances of preterm birth, especially if you had a premature baby before.

Things You Can't Control During Pregnancy

Some things that may increase the chances of a premature birth are out of your control. This doesn't mean that your baby will be born sick or too early. Remember, most babies are born healthy.

Here are some things you can't control during pregnancy:

Your age. Mothers who are 17 or younger or 35 or older are more likely to have a premature baby. Teen moms are more likely to get high blood pressure during pregnancy and less likely to get the health care they need. Older women are more likely to have health problems before they get pregnant.
The number of babies (multiples). The chances of having a premature baby go up if the mother is pregnant with twins, triplets, or more. More than half of all twins are born early.
Your health. Moms with problems like diabetes, depression, or high blood pressure may need to see their health care professional more often to keep these conditions under control.
Problems with an earlier pregnancy. A woman who has had a previous early delivery, or a baby born with health problems or a birth defect, is more likely to have problems in future pregnancies too.
Other factors. It's not clear why, but black women are more likely to have premature babies than white and Hispanic women.

If you're pregnant or are planning to be, talk with your health care professional. Women who get regular prenatal care are more likely to have a healthier pregnancy and baby.

Reviewed by: Thinh Phu Nguyen, MD

Date reviewed: August 2022

Premature babies - causes, symptoms, diagnosis and treatment

Premature babies are babies born before term, functionally immature, weighing less than 2500 g and body length less than 45 cm. Clinical signs of prematurity include disproportionate physique, open seams skull and small fontanel, inexpressiveness of the subcutaneous fat layer, hyperemia of the skin, underdevelopment of the genital organs, weakness or absence of reflexes, weak cry, intense and prolonged jaundice, etc. Nursing premature babies involves the organization of special care - temperature, humidity, oxygenation level, feeding, if necessary - conducting intensive care.

General information

Babies born between 28 and 37 weeks of gestation, weighing 1000-2500 g and body length 35-45 cm, are considered premature. The most stable criterion is gestational age; anthropometric indicators, due to their significant variability, are conditional criteria for prematurity. Every year, as a result of spontaneous premature birth or artificially induced termination of pregnancy in the later stages, 5-10% of children from the total number of newborns are born prematurely.

According to the WHO definition (1974), a fetus is considered viable with a gestational age of more than 22 weeks, a body weight of 500 g, a body length of 25 cm. g and length less than 35 cm is regarded as a late miscarriage. However, if such a child was born alive and lived after birth for at least 7 days, he is registered as premature. The level of neonatal mortality among premature babies is much higher than that among full-term babies, and largely depends on the quality of medical care in the first minutes and days of a child's life.

Premature babies

Causes of prematurity

All causes leading to the birth of premature babies can be grouped into several groups. The first group includes socio-biological factors, including too young or old age of parents (under 18 and over 40), bad habits of a pregnant woman, malnutrition and unsatisfactory living conditions, occupational hazards, unfavorable psycho-emotional background, etc. Risk of premature delivery and birth premature babies are higher in women who did not plan a pregnancy and neglect medical support for pregnancy.

The second group of reasons is burdened obstetric and gynecological history and pathological course of the present pregnancy in the expectant mother. Here, a history of abortion, multiple pregnancy, gestosis, hemolytic disease of the fetus, and premature detachment of the placenta are of the greatest importance. The reason for the birth of premature babies can be short (less than 2 years) intervals between births. Premature babies are often born to women who resort to in vitro fertilization, but this is not due to the very fact of using ART, but rather to the “female” factor that prevents natural fertilization. Gynecological diseases and malformations of the genitals adversely affect pregnancy: cervicitis, endometritis, oophoritis, fibroma, endometriosis, bicornuate saddle uterus, uterine hypoplasia, etc.

The third group of causes that disrupt the normal maturation of the fetus and cause an increased likelihood of the birth of premature babies include various extragenital diseases of the mother: diabetes mellitus, hypertension, heart defects, pyelonephritis, rheumatism, etc. Often, premature birth is provoked by acute infectious diseases suffered by a woman at late gestation.

Finally, the birth of premature babies may be associated with pathology and abnormal development of the fetus itself: chromosomal and genetic diseases, intrauterine infections, severe malformations.

Classification of prematurity

Taking into account the indicated criteria (gestational age, body weight and length), 4 degrees of prematurity are distinguished: body weight of the child at birth is 2500-2001 g, length - 45-41 cm. body weight of a child at birth is 2001-2500 g, length - 40-36 cm.

III degree of prematurity - delivery occurs at 31-28 weeks of gestation; birth weight of the child is 1500-1001 g, length - 35-30 cm. the birth weight of the child is less than 1000 g, the length is less than 30 cm. The term "premature with extremely low body weight" is used in relation to such children.

External signs of prematurity

Premature babies are characterized by a number of clinical signs, the severity of which correlates with the degree of prematurity.

Very preterm infants weighing <1500 are born with thin, wrinkled skin, richly covered with cheesy grease and vellus hair (lanugo). The skin has a bright red color (the so-called simple erythema), which turns pale by 2-3 weeks of age. The subcutaneous fat layer is absent (hypotrophy II-II degree), the child's physique is disproportionate (the head is large and is approximately 1/3 of the body length, the limbs are relatively short). The abdomen is large, flattened with a clearly visible divergence of the rectus muscles, the navel is located in the lower abdomen.

In severely preterm infants, all fontanelles and sutures of the skull are open, the cranial bones are supple, the brain skull prevails over the facial one. Characterized by underdevelopment of the auricles, poor development of the nails (nail plates do not reach the fingertips), weak pigmentation of the nipples and areola. The genital organs in premature babies are underdeveloped: in girls there is a gaping of the genital slit, in boys - undescended testicles into the scrotum (cryptorchidism).

Premature babies born at 33-34 weeks of gestation and later are characterized by greater maturity. Their appearance is distinguished by the pink color of the skin, the absence of fluff on the face and torso, a more proportional physique (smaller head, higher navel, etc.). In premature babies of I-II degree, the bends of the auricles are formed, the pigmentation of the nipples and areola circles is pronounced. In girls, the large labia almost completely cover the genital gap; in boys, the testicles are located at the entrance to the scrotum.

Anatomical and physiological features of premature babies

Prematurity is determined not so much by anthropometric indicators as by morphological and functional immaturity of vital organs and body systems.

Characteristic features of the respiratory organs in premature infants are the narrowness of the upper respiratory tract, the high position of the diaphragm, the compliance of the chest, and the perpendicular arrangement of the ribs relative to the sternum. These morphological features of premature babies cause superficial, frequent, weakened breathing (40-70 per minute), a tendency to apnea lasting 5-10 seconds (apnea of prematurity). Due to the underdevelopment of the elastic tissue of the lungs, the immaturity of the alveoli, and the reduced content of surfactant in premature babies, a syndrome of respiratory disorders easily occurs (congestive pneumonia, respiratory distress syndrome).

The immaturity of the cardiovascular system is characterized by pulse lability, tachycardia 120-180 per minute, muffled heart tones, arterial hypotension (55-65/20-30 mm Hg). In the presence of congenital heart defects (open ductus arteriosus, open foramen ovale), murmurs may be heard. Due to the increased fragility and permeability of the vascular walls, hemorrhages easily occur (subcutaneous, into internal organs, into the brain).

Morphological signs of CNS immaturity in preterm infants are weak differentiation of gray and white matter, smoothness of the brain sulci, incomplete myelination of nerve fibers, depleted vascularization of subcortical zones. Muscle tone in premature babies is weak, physiological reflexes and motor activity are reduced, the reaction to stimuli is slowed down, thermoregulation is impaired, and there is a tendency to both hypo- and hyperthermia. In the first 2-3 weeks, a premature baby may experience transient nystagmus and strabismus, tremors, shudders, stop clonus.

Premature infants have functional immaturity of all parts of the gastrointestinal tract and low enzyme excretion activity. In this regard, premature babies are prone to regurgitation, the development of flatulence, dysbacteriosis. Jaundice in premature babies is more intense and lasts longer than in full-term newborns. Due to the immaturity of the liver enzyme systems, the increased permeability of the blood-brain barrier, and the rapid breakdown of red blood cells, premature infants can easily develop bilirubin encephalopathy.

Functional immaturity of the kidneys in premature infants leads to changes in the electrolyte balance (hypocalcemia, hypomagnesemia, hypernatremia, hyperkalemia), decompensated metabolic acidosis, a tendency to edema and rapid dehydration with inadequate care.

The activity of the endocrine system is characterized by a delay in the development of the circadian rhythm of hormone release, and rapid depletion of the glands. In premature babies, there is a low synthesis of catecholamines, transient hypothyroidism often develops, and a sexual crisis rarely occurs in the first days of life (physiological mastitis, physiological vulvovaginitis in girls).

Preterm infants develop early anemia more rapidly than full-term infants, there is an increased risk of developing septicemia (sepsis) and septicopyemia (purulent meningitis, osteomyelitis, necrotizing ulcerative enterocolitis).

During the first year of life, the increase in body weight and length in premature babies is very intensive. However, according to anthropometric indicators, premature babies catch up with their peers born at term only by 2-3 years (sometimes by 5-6 years). The lag in psychomotor and speech development in premature babies depends on the degree of prematurity and comorbidity. In a favorable scenario for the development of a premature baby, alignment occurs in the 2nd year of life.

Further physical and psychomotor development of premature babies may be on par with their peers or be delayed.

Among premature babies, neurological disorders are more common than among full-term peers: astheno-vegetative syndrome, hydrocephalus, convulsive syndrome, vegetative-vascular dystonia, cerebral palsy, hyperactivity, functional dyslalia or dysarthria. Almost a third of premature babies have a pathology of the organ of vision - myopia and astigmatism of varying severity, glaucoma, strabismus, retinal detachment, optic nerve atrophy. Premature babies are prone to frequent repeated SARS, otitis media, against which hearing loss may develop.

Women born prematurely in adult life often suffer from menstrual irregularities, signs of sexual infantilism; they may be at risk of spontaneous abortion and premature birth.

Specific care for premature babies

Babies born prematurely need special care. Their phased nursing is carried out by neonatologists and pediatricians, first in the maternity hospital, then in the children's hospital and polyclinic. The main components of caring for premature babies are: ensuring optimal temperature and humidity conditions, rational oxygen therapy and metered feeding. In premature babies, constant monitoring of the electrolyte composition and CBS of the blood, monitoring of the gas composition of the blood, pulse and blood pressure is carried out.

Very premature babies are placed immediately after birth in incubators, where, taking into account the condition of the child, a constant temperature (32-35 ° C), humidity (in the first days about 90%, then 60-50%), oxygenation level (about 30% ). Premature babies of I-II degree are usually placed in heated beds or in ordinary beds in special boxes, where the air temperature is maintained at 24-25°C.

Premature babies who are able to independently maintain normal body temperature, who have reached a body weight of 2000 g, with good epithelialization of the umbilical wound, can be discharged home. The second stage of nursing in specialized departments of children's hospitals is indicated for premature infants who have not reached 2000 g in the first 2 weeks, and for children with perinatal pathology.

Feeding of premature babies should be started already in the first hours of life. Children with absent sucking and swallowing reflexes are fed through a gastric tube; if the sucking reflex is sufficiently pronounced, but the body weight is less than 1800 g, the child is fed through the nipple; children weighing over 1800 g may be breastfed. The frequency of feeding premature babies I-II degree 7-8 times a day; III and IV degree - 10 times a day. Calculation of food is made according to special formulas.

Premature infants with physiological jaundice should receive phototherapy (general UV). As part of the rehabilitation of premature babies at the second stage, communication between the child and the mother, skin-to-skin contact, is useful.

Clinical examination of premature babies

After discharge, children born prematurely need constant supervision by a pediatrician during the first year of life. Examinations and anthropometry are carried out weekly in the first month, once every two weeks - in the first half of the year, once a month - in the second half of the year. In the first month of life, premature babies should be examined by a pediatric surgeon, pediatric neurologist, pediatric orthopedic traumatologist, pediatric cardiologist, pediatric ophthalmologist. At the age of 1 year, children need to consult a speech therapist and a child psychiatrist.

From the age of 2 weeks, premature babies need prevention of iron deficiency anemia and rickets. Preventive vaccinations for premature babies are carried out according to an individual schedule. In the first year of life, repeated courses of baby massage, gymnastics, individual wellness and tempering procedures are recommended.

Premature babies - causes, symptoms, diagnosis and treatment

Premature babies are babies born before term, functionally immature, weighing less than 2500 g and body length less than 45 cm. Clinical signs of prematurity include a disproportionate physique, open sutures of the skull and a small fontanel, lack of expression of the subcutaneous fat layer, hyperemia of the skin, underdevelopment of the genital organs, weakness or absence of reflexes, weak cry, intense and prolonged jaundice, etc. Nursing premature babies involves the organization of special care - temperature, humidity, oxygenation level , feeding, if necessary - conducting intensive care.

General information

Premature babies

Causes of prematurity

Finally, the birth of premature babies may be associated with pathology and abnormal development of the fetus itself: chromosomal and genetic diseases, intrauterine infections, severe malformations.

Classification of prematurity

External signs of prematurity

Premature babies are characterized by a number of clinical signs, the severity of which correlates with the degree of prematurity.

Anatomical and physiological features of premature babies

Prematurity is determined not so much by anthropometric indicators as by morphological and functional immaturity of vital organs and body systems.

Further physical and psychomotor development of premature babies may be on par with their peers or be delayed.

Women born prematurely in adult life often suffer from menstrual irregularities, signs of sexual infantilism; they may be at risk of spontaneous abortion and premature birth.