An illegitimate child is one who is born of parents who were not legally married to one another at the time of the child’s birth, and who remain unmarried to one another.
By law and jurisprudence, the mother of an illegitimate child has sole parental authority and is entitled to keep the child in her company. This rule continues to apply even when the father of the child acknowledges filiation (paternity), although the court may order the father to provide support as a result of the acknowledgment, but not custody.
In one case (Briones vs. Miguel, GR 156343, Oct. 18, 2004), the Supreme Court upheld the illegitimate child’s mother’s custody even when the mother was working in Japan and eventually brought the child out of the country to live with her there.
True, there are exceptions to this rule but only when there are compelling reasons to deprive the mother of custody. Examples are neglect or abandonment, unemployment, immorality, habitual drunkenness, drug addiction, maltreatment of the child, insanity, and affliction with a communicable disease.
Merely working abroad while entrusting the child to the care of the maternal grandparents or other immediate family member does not seem to be one of the grounds for taking away custody from the mother. It cannot be considered as abandonment or neglect as well.