Prematurity

Symptoms

• Regular uterine contractions or tightening, often every 10 minutes or more frequent (maternal)
• Change in vaginal discharge (watery, mucus-like, or bloody) (maternal)
• Constant low, dull backache (maternal)
• Pelvic or lower abdominal pressure (maternal)
• Mild abdominal cramps, with or without diarrhea (maternal)
• Small size and low birth weight (less than 2500 grams) (neonate)
• Disproportionately large head (neonate)
• Low body temperature (hypothermia) due to lack of body fat (neonate)
• Respiratory distress, including grunting, nasal flaring, retractions (pulling in of the skin between the ribs or under the breastbone), apnea (pauses in breathing), or cyanosis (bluish skin color) (neonate)
• Fine body hair (lanugo) (neonate)
• Weak cry and poor muscle tone (hypotonia) (neonate)
• Immature reflexes, such as poor suck/swallow coordination (neonate)
• Translucent, thin, or shiny skin (neonate)
• Severe respiratory distress or apnea (emergency neonate)
• Significant temperature instability (emergency neonate)
• Seizures (emergency neonate)
• Poor perfusion (pale or blue skin) (emergency neonate)
• Inability to feed (emergency neonate)

Causes & Risk Factors

• Spontaneous Preterm Labor: Labor begins on its own with intact membranes, accounting for approximately 40-50% of preterm births.
• Preterm Prelabor Rupture of Membranes (PPROM): The amniotic sac breaks before the onset of labor, accounting for approximately 20-30% of preterm births.
• Provider-Initiated (Iatrogenic) Preterm Birth: Delivery is recommended by healthcare providers for maternal or fetal health indications, accounting for approximately 30-35% of preterm births.
• Maternal indications for provider-initiated preterm birth include preeclampsia, eclampsia, HELLP syndrome, placental abruption, or placenta previa with hemorrhage.
• Fetal indications for provider-initiated preterm birth include fetal distress, fetal growth restriction, or certain fetal anomalies.
• The specific trigger for spontaneous preterm labor is often unknown, as it is a complex syndrome with multiple overlapping pathways.
• Potential pathways contributing to spontaneous preterm labor include infection/inflammation (intrauterine or systemic), uterine overdistension (e.g., multiple gestation, polyhydramnios), decidual hemorrhage/vascular issues (e.g., abruption), maternal or fetal stress (activation of the hypothalamic-pituitary-adrenal axis), and cervical disease.
• Previous spontaneous preterm birth (strongest predictor)
• Multiple gestation (e.g., twins, triplets)
• Short cervical length (less than 25 mm in the mid-trimester)
• Uterine or cervical abnormalities (e.g., fibroids, bicornuate uterus, prior cervical surgery)
• Maternal age less than 17 or greater than 35 years
• Race and ethnicity (e.g., higher rates in non-Hispanic Black women in the US)
• Genetic predisposition
• Short interpregnancy interval (less than 18 months between pregnancies)
• Certain infections during pregnancy (e.g., urinary tract infections, bacterial vaginosis, sexually transmitted infections)
• Periodontal disease
• Maternal health conditions such as hypertension, preeclampsia, or diabetes
• Substance use, including smoking, alcohol, or illicit drugs
• Low socioeconomic status, high stress levels, or lack of social support
• Low pre-pregnancy weight or poor nutrition
• In vitro fertilization (IVF) and other assisted reproductive technologies (partially due to increased risk of multiple gestation)
• Adequate interpregnancy interval (a protective factor)
• Progesterone supplementation in high-risk women (e.g., history of preterm birth or short cervix) (a protective factor)
• Cervical cerclage in select high-risk women (a protective factor)
• Good prenatal care and management of chronic health conditions (a protective factor)

Diagnosis

• Review of medical history, including risk factors, prior obstetric history, and current symptoms (e.g., contraction timing, vaginal discharge, bleeding) for preterm labor.
• Physical examination, including a sterile speculum exam to assess for ruptured membranes (pooling of fluid, ferning, nitrazine test) for preterm labor.
• Digital cervical exam to assess for cervical dilation and effacement (may be deferred if preterm prelabor rupture of membranes is suspected) for preterm labor.
• Transvaginal Ultrasound (TVUS) to measure cervical length; a short cervix (less than 25-30mm) increases the likelihood of preterm birth.
• Fetal Fibronectin (fFN) Test on cervicovaginal secretions; a negative result has a high predictive value for ruling out delivery within the next 7-14 days.
• Tocodynamometry, which is external monitoring to assess uterine contraction frequency and duration.
• Diagnosis of preterm labor is made when there are regular uterine contractions accompanied by cervical change (dilation and/or effacement) before 37 weeks of gestation.
• Diagnosis of prematurity in a neonate is based on the assessment of gestational age.
• Methods for assessing gestational age include the date of the mother's last menstrual period (LMP), early pregnancy ultrasound measurements (considered the most accurate method), and postnatal physical and neuromuscular maturity examination (e.g., New Ballard Score).

Treatment Options

• Antenatal Corticosteroids (e.g., Betamethasone, Dexamethasone) administered to the mother between 23 and 34 weeks of gestation at risk of preterm delivery to accelerate fetal lung maturity and reduce the risk of neonatal respiratory distress syndrome, intraventricular hemorrhage, and necrotizing enterocolitis.
• Tocolytic Therapy (e.g., Nifedipine, Indomethacin, Terbutaline) to temporarily stop or slow uterine contractions, typically to allow time for corticosteroids to work and/or for transfer to a facility with a higher level of neonatal care. The choice of first-line tocolytic agent can vary, with some guidelines recommending nifedipine.
• Magnesium Sulfate administered to mothers at risk of imminent preterm birth before 32 weeks of gestation for fetal neuroprotection, to reduce the risk and severity of cerebral palsy.
• Antibiotics for Group B Streptococcus (GBS) prophylaxis if status is positive or unknown, and in cases of preterm prelabor rupture of membranes (PPROM) to prolong latency and reduce maternal/neonatal infection.
• Neonatal Intensive Care Unit (NICU) Admission, required for most preterm infants, especially those born very or extremely preterm.
• Thermoregulation using incubators, radiant warmers, and skin-to-skin contact (Kangaroo Mother Care) to maintain the baby's body temperature.
• Respiratory Support, which may range from supplemental oxygen via nasal cannula to continuous positive airway pressure (CPAP) or mechanical ventilation. Surfactant replacement therapy may be administered for Respiratory Distress Syndrome (RDS).
• Nutritional Support, starting with intravenous (IV) fluids and parenteral nutrition, followed by gradual introduction of enteral feeds (breast milk is strongly recommended) via gavage tube until suck/swallow/breathe coordination develops.
• Careful Fluid and Electrolyte Management due to immature kidney function and high insensible water losses.
• Infection Management, including prophylactic measures and prompt treatment of suspected or confirmed sepsis.
• Long-term, multidisciplinary follow-up to monitor growth, neurodevelopmental outcomes, vision, and hearing for the preterm infant.

Frequently Asked Questions