Should newborns at 22 or 23 weeks’ gestational age be aggressively resuscitated?

For many decades the limit of viability was believed to be approximately 24 weeks of gestation. In many medical centers, newborns delivered at less than 25 weeks are evaluated in the delivery room and the decision to resuscitate is based on the infant’s clinical response. In the past, aggressive and extended resuscitation of newborns at 22 and 23 weeks was not common because the prognosis was bleak and clinicians did not want to inflict unnecessary pain when the chances for survival were limited. Recent advances in obstetric and pediatric care, however, have resulted in the survival of some infants born at 22 weeks’ gestation, calling into question long-held beliefs about the limits of viability.

In 2 recent reports, investigators used data from the National Institute of Child Health and Human Development (NICHD) Neonatal Research Network to acquire detailed information about newborn survival and morbidity at 22 through 28 weeks’ gestation (TABLES 1 and 2).^1,2 These data show that the survival of newborns at 23 through 27 weeks’ gestation is increasing, albeit slowly. Survival, without major morbidity, is gradually improving for newborns at 25 through 28 weeks.^1,2 But what is the prognosis for a fetus born at 22 or 23 weeks?

There are several aspects of this issue to consider, including accurate dating of the gestational age and current viability outcomes data.

Determining the limit of viability: Accurate dating is essentialThe limit of viability is the milestone in gestation when there is a high probability of extrauterine survival. A major challenge in studies of the limit of viability for newborns is that accurate gestational dating is not always available. For example, in recent reports from the NICHD Neonatal Research Network the gestational age was determined by the best obstetric estimate, or the Ballard or Dubowitz examination, of the newborn.^1,2

It is well known that ultrasound dating early in gestation is a better estimate of gestational age than last menstrual period, uterine sizing, or pediatric examination of the newborn. Hence, the available data are limited by the absence of precise gestational dating with early ultrasound. Data on the limit of viability with large numbers of births between 22 and 24 weeks with early ultrasound dating would help to refine our understanding of the limit of viability.

At 23 weeks, each day of in utero development is criticalThe importance of each additional day spent in utero during the 23rd week of gestation was demonstrated in a small cohort in 2001.⁴ Overall, during the 23rd week of gestation the survival of newborns to discharge was 33%.⁴ This finding is similar to the survival rate reported by the NICHD Neonatal Research Network in 2012.¹ However, survival was vastly different early, compared with later, in the 23rd week⁴:

• from 23 weeks 0 days to 23 weeks 2 days: no newborn survived
• at 23 weeks 3 days and 23 weeks 4 days: 40% of newborns survived
• at 23 weeks 5 days and 23 weeks 6 days: 63% of newborns survived (a similar survival rate of 24-week gestations was reported by the NICHD Neonatal Research Network¹).

The development of the fetus across the 23rd week of gestation appears to be critical to newborn survival. Hence, every day of in utero development during the 23rd week is critically important. A great challenge for obstetricians is how to approach the woman with threatened preterm birth at 22 weeks 0 days’ gestation. If the woman delivers within a few days, the likelihood of survival is minimal. However, if the pregnancy can be extended to 23 weeks and 5 days, survival rates increase significantly.

Aligning the actions of birth team, mother, and familyFactors that influence the limit of viability include:

• gestational age
• gender of the fetus (Females are more likely than males to survive.)
• treatment of the mother with glucocorticoids prior to birth
• newborn weight.

To increase the likelihood of newborn survival, obstetricians need to treat women at risk for preterm birth with antenatal glucocorticoids and antibiotics for rupture of membranes and to limit fetal stress during the birth process. Guidelines have evolved to encourage clinicians to treat women at preterm birth risk with glucocorticoids either at:

• 23 weeks’ gestation or
• 22 weeks’ gestation, if birth is anticipated to occur at 23 weeks or later.⁵

At birth, pediatricians are then faced with the very difficult decision of whether or not to aggressively resuscitate the severely preterm infant. Complex medical, social, and ethical issues ultimately guide pediatricians’ actions in this challenging situation. It is important for their actions to be in consensus with the obstetrician, the mother, and the mother’s family and for a consensus to be reached. Dissonant plans may increase adverse outcomes for the newborn. In one study when pediatricians and obstetricians were not aligned in their actions, the risk of death of an extremely preterm newborn significantly increased.⁶