Drs Kamath-Rayne and DeFranco have addressed 3 primary concerns with our recent editorial regarding the case for using amniocentesis in the management of complicated pregnancies that are late-preterm and/or early-term. In response to the first concern of potential long-term concerns for preterm neonates, we are not proposing the “elective” delivery of 34 weeks’ gestations or any late-preterm and/or early-term pregnancy before 39 weeks’ gestation. This should only occur if a clinical disorder suggests that delivery may be better than nondelivery for the mother or the fetus, especially if we can anticipate a benign neonatal course. We concur that preterm neonates probably have more long-term consequences than term newborns, but early delivery before term will occur regardless if one were to follow the ACOG and SMFM protocols for late-preterm and/or early-term delivery based on certain clinical disorders without FLM testing or if one were to use FLM testing in the management scheme. What cannot be pared out in any of the neonatal data, including the information supplied in the recent article by Kugelman et al, is whether neurodevelopment issues are less in those preterm neonates that have mature lungs compared with those that are immature in complicated pregnancies.

The second concern describes a neonate that had mild respiratory distress syndrome (RDS) after delivery at 35 weeks 4 days and a mature lecithin to sphingomyelin ratio test result. Nearly every study that has examined a specific type of FLM test will have a small number of cases where RDS has occurred after a mature test result, and virtually always, these cases are mild and not associated with other major neonatal complications of prematurity. Fetal lung maturity tests do not have a 100% negative predictive value. However, these case reports further argue that all centers that perform FLM testing need to have good quality control measures in place to continually analyze overall performance.

Lastly, concerning the issue of using corticosteroid treatment in late-preterm and/or early-term gestations after an immature fetal lung maturity test, the editorial clearly states that further study needs to occur before this can or cannot be recommended. The study of Kamath et al, compared the outcome of 3 different groups of patients that included those delivered after a mature FLM test, those that were expectantly managed after an immature FLM test, and those that received corticosteroids and were delivered within a week after an immature FLM test. The mature amniocentesis and expectant management groups had less adverse respiratory outcomes when compared with the corticosteroid group. However, the study by Yinon et al, analyzed pregnancies that had immature FLM testing and compared outcomes based on those treated with corticosteroids vs no treatment and showed the opposite where the steroid group had less composite neonatal morbidity. Multiple regression analysis in their study showed that corticosteroid treatment was independently associated with a lower composite morbidity outcome. We would argue that the groups of patients in both of these evaluations may not be comparable as these studies were not randomized and there are often clinical differences that dictate the choice of delivery vs expectant management vs corticosteroids. Neither study fully addresses the question regarding whether corticosteroid treatment is of benefit in the setting of an immature FLM test. The only definitive way to evaluate this clinical question would be to perform a multicenter study of a large number of late-preterm and/or early-term pregnancies that have immature FLM testing and randomize this group to corticosteroids vs placebo with delivery in a week of treatment and analyze overall maternal and neonatal outcome. In addition, many neonates delivered after 34 weeks’ gestation will not have significant respiratory complications and the Maternal-Fetal Medicine Units Network ALPS trial will also not fully address the specific question of whether corticosteroids would be beneficial in the setting of an immature FLM test in this gestational age population.

To conclude, not all pregnancies are black and white when it comes to the management of certain complicated obstetric disorders. Many of these pregnancies fall in a gray area and we do not have enough clinical information to abandon FLM amniocentesis as a management option. We would argue that a less selective approach in treating all pregnancies at a given gestational age is a step back in time and the age of fetal medicine was heralded by our ability to determine which neonates are likely to do better in the nursery. Knowing everything we can about mother and fetus will only improve our ability to make the best decision regarding delivery.