No differences were observed between the Butantan ( n = 154 ) and control ( n = 173 ) groups in relation to birth weight , gestational age , sex , and prenatal use of corticosteroids , or in mortality rates both at 72 hours ( 14.19 % versus 14.12 % ; p = 0.98 ) and at 28 days ( 39.86 % versus 33.33 % ; p = 0.24 ) of life .