By: Alex Muller, Lauren Harnois, Anna Kuruc, and Urvinder Kaur 

       Infants who are born after 40 weeks’ gestation are technically considered full-term; however, many may develop distresses in utero from a lengthened time in the womb or other predisposing factors. In this specific case, a 35 year-old primigravida has a greater risk for developing complications during pregnancy as compared to younger females. With nearly a 20% increased risk of developing the possibility of a miscarriage and a 25% increased risk of structural defects of the fetus, this newborn seems to have an added chance of developing problems.¹ Although the increased risk of a miscarriage has been surpassed, the concern for structural defects may be one of the underlying concerns for the medical team.

      Prior to the induction of labor at 41 weeks, it was understood that oligohydramnios was present and late and variable decelerations were observed during labor. Oligohydramnios can be defined as having <5 cm amniotic fluid index or <2 cm single deepest pocket of amniotic fluid. It can be found in an otherwise uncomplicated birth, but poses an added threat to a potentially difficult pregnancy.  Many studies found additional complications of oligohydramnios including, meconium staining, meconium aspiration syndrome (MAS), 5 minute APGAR score <7, respiratory distress syndrome, and umbilical cord gas <7.10.² As this is already a high-risk pregnancy, the depleted amniotic fluid index creates more concern for the physician and medical staff. Amniotic fluid is vital to protecting the fetus, so when there is a decreased index, the consequences of variable fetal heart rate and umbilical cord occlusion (UCO) become more apparent.³ It is evident that the fetus has developed both of these risk factors from intrapartum cardiac monitoring as well as post labor assessments of agonal breathing, which may be related to a UCO.³ If the fetus develops UCO for a prolonged period of time, outcome may be poor. Variable decelerations are often associated with moderate to severe acidosis and hypoxemia in infants.

Meconium aspiration syndrome is one of the most common causes of severe respiratory distress inpost-term gestation, so providing adequate ventilatory support is of the utmost concern. Conventional mechanical ventilation can easily cause trauma to the newborn infant, so high frequency oscillatory ventilation (HFOV) has been used as a lung protective strategy.⁴ HFOV produces biphasic pressure changes that oscillate around a constant mean airway pressure at a high frequency, which has been shown to provide acceptable oxygenation and ventilation. In addition to the ventilatory support, reducing the pulmonary vascular resistance and reversing the right-to-left shunt has been shown to have the most favorable outcomes in treating persistent pulmonary hypertension (PPHN) caused by meconium aspiration. Management of PPHN and respiratory distress syndrome can vary depending on the infant’s needs and required care. Therapies such as inhaled nitric oxide, dialysis for support of renal function, and extracorporeal membrane oxygenation (ECMO) may be required if the infant does not respond to conventional support as reflected in an oxygen index of > 40.⁵ If untreated, the typical route this condition follows can lead to ventilatory failure, neurologic problems, bronchopulmonary dysplasia and ultimately, death. Understanding the patient’s needs and efficiently treating the defect may lead to a positive prognosis.

References:

1. Loke AY, Poon CF. The health concerns and behaviours of primigravida: comparing advanced age pregnant women with their younger counterparts. J Clin Nurs 2011;20(7-8):1141-1150.
2. Rabie N, Magann E, Steelman S, Ounpraseuth S. Oligohydramnios in complicated and uncomplicated pregnancies: a systematic review and meta-analysis. Ultrasound Obstet Gynecol 2016.
3. Amaya KE, Matushewski B, Durosier LD, Frasch MG, Richardson BS, Ross MG. Accelerated acidosis in response to variable fetal heart rate decelerations in chronically hypoxic ovine fetuses. Am J Obstet Gynecol 2016;214(2):270.e1-270.e8.
4. Chen DM, Wu LQ, Wang RQ. Efficiency of high-frequency oscillatory ventilation combined with pulmonary surfactant in the treatment of neonatal meconium aspiration syndrome. Int J Clin Exp Med 2015;8(8):14490-14496.
5. https://www.ucsfbenioffchildrens.org/conditions/persistent_pulmonary_hypertension_of_the_newborn
6. https://bugswong.smugmug.com/keyword/meconium/i-w8njRzH