Article 168. If the marriage is terminated and the mother contracted another marriage within three hundred days after such termination of the former marriage, these rules shall govern in the absence of proof to the contrary:

(1) A child born before one hundred eighty days after the solemnization of the subsequent marriage is considered to have been conceived during the former marriage, provided it be born within three hundred days after the termination of the former marriage;

(2) A child born after one hundred eighty days following the celebration of the subsequent marriage is considered to have been conceived during such marriage, even though it be born within three hundred days after the termination of the former marriage. (259a)


     According to the provisions of the above article, one of the requisites for the child to be considered child of the first marriage is that the child must have been born within 300 days after the termination of the first marriage and the said child must have been born within 180 days after the solemnization of the second marriage. 




Reference: 
Family Code by Albano