In Reply We stated in our article that “[o]utcomes beyond early childhood have not been reported from any of the RCTs to date.” This was correct at the time of submission; however, we acknowledge that the French PREMAG study1 has subsequently reported results at school age prior to our publication. We agree with Drs Marret and Bénichou, from the PREMAG study, that social and environmental variables are important influences on child development and may contribute to difficulty in finding longer-term effects of early treatments. A recent example where this may have occurred was in the Caffeine for Apnea of Prematurity randomized trial in which caffeine therapy during the first weeks after birth reduced the rates of cerebral palsy and developmental delay at 18 months corrected age2 but did not do so for either cerebral palsy3 or intellectual impairment4 at 5 years of age.
Doyle LW, Anderson PJ, Lee KJ. Antenatal Magnesium Sulfate and Outcomes for School-aged Children—Reply. JAMA. 2015;313(3):306-307. doi:10.1001/jama.2014.15915