Post-maturity syndrome

Overview

Post-maturity syndrome, also known as post-term syndrome, is a condition that affects newborns who are delivered after 42 weeks of gestation (294 days), which is beyond the typical full-term pregnancy period of 37–42 weeks. Infants with post-maturity syndrome often show signs of intrauterine growth restriction and decreased placental function, leading to distinctive physical features and health risks. Although many post-term babies are healthy, a subset develops complications due to the aging placenta, reduced amniotic fluid, and compromised oxygen and nutrient delivery.

The incidence of post-maturity syndrome is estimated to affect 10% of pregnancies that go beyond 42 weeks. Early identification and management are essential to prevent adverse outcomes in both the fetus and the mother.

Causes

The precise cause of post-maturity syndrome is not always known, but several factors can contribute to prolonged pregnancy and associated fetal complications:

• Inaccurate dating: Miscalculation of the gestational age due to uncertain last menstrual period (LMP) or late first-trimester ultrasound.

• First-time pregnancies: Primigravida women are more likely to have prolonged gestation.

• Previous post-term pregnancy: A history of post-term delivery increases the likelihood in subsequent pregnancies.

• Genetic factors: Family history may play a role in extended gestational duration.

• Placental insufficiency: Aging placenta may deteriorate in function after 40 weeks, resulting in decreased oxygen and nutrient transfer.

In many cases, the reason for post-term pregnancy is idiopathic (unknown).

Symptoms

Infants with post-maturity syndrome typically show physical and clinical signs of prolonged intrauterine existence and placental compromise. Common features include:

Physical Signs

• Dry, peeling skin: Due to loss of protective vernix caseosa and exposure to amniotic fluid for an extended period.

• Overgrown nails and hair: Fingernails and scalp hair may appear unusually long.

• Minimal subcutaneous fat: Leading to a thin, wasted appearance.

• Wrinkled or parchment-like skin: Often described as "aged" in appearance.

• Green or yellow skin staining: From meconium-stained amniotic fluid, indicating fetal stress.

Clinical Complications

• Fetal distress: Caused by reduced oxygen supply, potentially leading to abnormal heart rate patterns.

• Meconium aspiration syndrome (MAS): Inhalation of meconium-stained fluid can cause breathing problems.

• Hypoglycemia: Due to reduced glycogen and fat reserves.

• Oligohydramnios: Low amniotic fluid levels, increasing the risk of cord compression and labor complications.

• Macrosomia: Some post-term infants may be large for gestational age, increasing the risk of birth trauma.

In severe cases, stillbirth may occur due to prolonged placental insufficiency.

Diagnosis

Post-maturity syndrome is diagnosed based on gestational age and the physical appearance of the newborn. Diagnostic steps include:

• Accurate gestational dating: Based on last menstrual period and confirmed by first-trimester ultrasound to prevent misclassification.

• Prenatal monitoring: In post-term pregnancies, fetal well-being is monitored using:

  • Non-stress test (NST)

  • Biophysical profile (BPP)

  • Amniotic fluid index (AFI)

• Clinical examination at birth: Observation of physical features such as dry skin, meconium staining, and low fat stores.

In cases of suspected fetal compromise, additional investigations like Doppler ultrasound may be used to assess placental blood flow.

Treatment

Treatment of post-maturity syndrome focuses on prenatal monitoring, timely delivery, and immediate postnatal care:

During Pregnancy

• Frequent fetal monitoring: Initiated around 41 weeks to assess fetal health and detect signs of distress.

• Induction of labor: Often recommended between 41 and 42 weeks to avoid complications, particularly if signs of placental insufficiency are present.

At Birth

• Neonatal resuscitation: May be necessary in cases of fetal distress or meconium aspiration.

• NICU admission: For infants with respiratory issues, hypoglycemia, or other complications.

• Glucose monitoring and feeding support: To manage energy deficiencies and prevent hypoglycemia.

• Observation for meconium aspiration: If the infant has difficulty breathing or low oxygen levels.

Long-term monitoring and developmental assessments may be needed in severe or complicated cases.

Prognosis

The prognosis for infants with post-maturity syndrome depends on the timing of intervention and the severity of complications. With proper prenatal care and timely delivery, most post-term infants recover well and go on to lead healthy lives.

However, without appropriate monitoring and intervention, the risks of stillbirth, birth trauma, and neonatal morbidity increase significantly. Key factors that influence prognosis include:

• Quality and timing of prenatal care

• Extent of placental dysfunction

• Presence of complications like MAS or hypoglycemia

• Birth weight and gestational age at delivery

Preventive strategies such as routine prenatal ultrasounds, induction protocols, and close postnatal observation help ensure favorable outcomes in most cases of post-maturity syndrome.