Prematurity is defined as the birth of an infant before 37 weeks of gestation. According to the World Health Organization (WHO), prematurity is the leading cause of neonatal mortality and morbidity worldwide.


Causes of prematurity

The exact causes of prematurity are not fully understood, but there are several factors that have been identified as potential contributors. These factors can be categorized into maternal, environmental, and medical factors.

A) Maternal Factors:

1. Previous Preterm Birth: Women who have previously given birth prematurely are at an increased risk of experiencing another preterm birth.

2. Multiple Pregnancies: Carrying twins, triplets, or more significantly increases the risk of preterm birth.

3. Infections: Certain infections during pregnancy, such as urinary tract infections, vaginal infections, and sexually transmitted infections, can increase the risk of preterm birth.

4. Chronic Conditions: Maternal chronic conditions like high blood pressure, diabetes, kidney disease, and autoimmune disorders can contribute to preterm birth.

5. Cervical Incompetence: Weakness in the cervix can lead to premature dilation and subsequent preterm birth.

6. Placental Problems: Issues with the placenta, such as placental abruption (separation of the placenta from the uterus) or placenta previa (placenta covering the cervix), can result in preterm birth.

7. Maternal Age: Both very young mothers (under 17 years old) and older mothers (over 35 years old) have a higher risk of preterm birth.


B) Environmental Factors:

1. Socioeconomic Status: Women from lower socioeconomic backgrounds may face challenges accessing adequate prenatal care and nutrition, increasing their risk of preterm birth.

2. Stress: High levels of stress during pregnancy have been associated with an increased likelihood of preterm birth.

3. Substance Abuse: Smoking tobacco, using illicit drugs, or consuming alcohol during pregnancy can significantly increase the risk of preterm birth.

4. Air Pollution: Exposure to high levels of air pollution, particularly fine particulate matter (PM2.5), has been linked to an increased risk of preterm birth.


C) Medical Factors:

1. Assisted Reproductive Technologies (ART): Women who conceive through in vitro fertilization (IVF) or other ART methods have a higher likelihood of preterm birth.

2. Fetal Growth Restriction: When the fetus does not grow adequately in the womb, it can lead to preterm birth.

3. Incompetent Cervix: A weakened cervix that is unable to support the weight of the growing fetus can result in preterm birth.

4. Maternal Medical Interventions: Certain medical interventions, such as induced labor or cesarean section without medical indication, may increase the risk of preterm birth.

It is important to note that prematurity often occurs due to a combination of these factors rather than a single cause. Additionally, in many cases, the exact cause remains unknown.


Assessment of Gestational Age at Birth

Gestational age refers to the length of time a fetus has been developing in the womb, typically measured in weeks. Accurate assessment of gestational age at birth is crucial for various reasons, including determining the appropriate management of preterm or post-term infants, estimating fetal growth and development, and predicting potential complications.

There are several methods used to assess gestational age at birth, each with its own advantages and limitations. These methods can be broadly categorized into two groups: prenatal and postnatal assessments.

A) Prenatal assessments of gestational age involve estimating the age of the fetus based on various parameters observed during pregnancy. These parameters include menstrual history, ultrasound measurements, and certain biochemical markers.

1. Menstrual History:

The most common method used to estimate gestational age is based on the woman’s last menstrual period (LMP). This method assumes a regular 28-day menstrual cycle with ovulation occurring on day 14. By subtracting 3 months from the LMP and adding 7 days, an estimated due date can be calculated. However, this method relies on accurate recall of the LMP and assumes a regular menstrual cycle, which may not always be the case.

2. Ultrasound Measurements:

Ultrasound is widely used to assess gestational age during pregnancy. It involves measuring various fetal parameters, such as crown-rump length (CRL), biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), and femur length (FL). These measurements are compared to standardized growth charts to estimate gestational age accurately. Ultrasound is considered one of the most reliable methods for assessing gestational age, especially in early pregnancy when fetal structures are well-defined.

3. Biochemical Markers:

Certain biochemical markers can also be used to estimate gestational age. For example, levels of human chorionic gonadotropin (hCG) and pregnancy-associated plasma protein-A (PAPP-A) can be measured in maternal blood samples. These markers are used in conjunction with other parameters, such as maternal age and nuchal translucency measurements, to estimate gestational age and assess the risk of chromosomal abnormalities.

B) Postnatal assessments of gestational age involve evaluating physical characteristics and developmental milestones observed in newborns. These assessments are particularly useful when prenatal information is unavailable or unreliable.

1. Ballard Score:

The Ballard score is a widely used postnatal assessment tool that evaluates physical and neuromuscular maturity in newborns. It involves assessing various physical characteristics, such as skin texture, lanugo, plantar creases, breast development, and genitalia development. The score obtained from this assessment can be correlated with gestational age.

2. Dubowitz Score:

The Dubowitz score is another postnatal assessment tool that evaluates physical and neuromuscular maturity in newborns. It involves assessing various parameters, including skin texture, lanugo, breast development, eye and ear formation, muscle tone, and reflexes. The score obtained from this assessment can also be correlated with gestational age.

3. New Ballard Score:

The New Ballard score is an updated version of the Ballard score that incorporates additional parameters and refinements to improve accuracy. It includes assessments of physical characteristics, neuromuscular maturity, and behavioral responses in newborns.

It is important to note that while these methods provide estimates of gestational age, they are not always precise. Variations in fetal growth patterns and individual differences can affect the accuracy of these assessments. Additionally, certain factors such as maternal health conditions or fetal abnormalities may further complicate the estimation of gestational age.

In conclusion, accurate assessment of gestational age at birth is crucial for various clinical purposes. Prenatal methods such as menstrual history, ultrasound measurements, and biochemical markers provide valuable information during pregnancy. Postnatal assessments using tools like the Ballard score, Dubowitz score, and New Ballard score help evaluate physical and neuromuscular maturity in newborns. However, it is important to consider the limitations and potential sources of error associated with these methods.


Complications of Prematurity

Premature babies are at higher risk for various health complications due to their underdeveloped organs and systems. Some common complications include:

1. Respiratory Distress Syndrome (RDS): Premature babies often have immature lungs, leading to difficulty in breathing. RDS occurs when the baby’s lungs lack a substance called surfactant, which helps keep the air sacs open.

2. Intraventricular Hemorrhage (IVH): IVH is bleeding into the brain’s ventricles, which can occur in premature infants due to fragile blood vessels in their underdeveloped brains.

3. Necrotizing Enterocolitis (NEC): NEC is a serious intestinal disease that primarily affects premature infants. It occurs when the tissue in the intestine becomes inflamed and starts to die.

4. Retinopathy of Prematurity (ROP): ROP is an eye disorder that affects premature infants. It occurs when abnormal blood vessels grow in the retina, potentially leading to vision problems or blindness.

5. Jaundice: Premature babies are more prone to jaundice, a condition characterized by yellowing of the skin and eyes due to elevated bilirubin levels.

6. Infections: Premature infants have a higher risk of developing infections due to their immature immune systems and prolonged hospital stays.


Prevention and Management of Prematurity

1. Progesterone supplementation: Progesterone supplementation has been shown to reduce the risk of preterm birth in women with a history of previous preterm birth or other risk factors.

2. Corticosteroid therapy: Corticosteroid therapy has been shown to improve fetal lung maturity and reduce the risk of RDS and BPD.

3. Antibiotic therapy: Antibiotic therapy is used to treat infections that can lead to preterm birth.

4. Bed rest: Bed rest may be recommended for women with preterm labor or other risk factors for preterm birth.

5. Cesarean delivery: Cesarean delivery may be recommended for women with certain risk factors for preterm birth.

6. Close monitoring: Close monitoring of the mother and fetus during pregnancy can help identify potential complications and prevent preterm birth.


Prognosis of Prematurity

The prognosis for premature infants has improved significantly over the past few decades due to advances in medical technology and care. However, premature infants are still at risk for a number of complications, including RDS, BPD, intracranial hemorrhage, and NEC. With proper care and management, many premature infants can grow up to lead healthy lives.