S1	(MH "Clonidine") OR clonidine	1,632
S2	alpha 2 agonists	664
S3	premature* OR prematurity OR preterm* OR very low birth OR low birth weight* OR vlbw OR lbw OR infant OR infan* OR newborn* OR neonate* OR neonat*	407,226
S4	(MH "Infant+") OR (MH "Infant, Newborn+")	217,072
S5	S3 OR S4	407,226
S6	S1 OR S2	2,193
S7	randomized controlled trial* OR controlled clinical trial OR randomized OR randomised OR randomly OR placebo OR trial OR groups OR study OR PT clinical trial OR clinical trial as topic OR cluster	2,230,803
S8	S5 AND S6 AND S7	139