SB 9.20.34

tasyāsan nṛpa vaidarbhyaḥ
 patnyas tisraḥ susammatāḥ
jaghnus tyāga-bhayāt putrān
 nānurūpā itīrite
Synonyms: 
tasya — of him (Mahārāja Bharata); āsan — there were; nṛpa — O King (Mahārāja Parīkṣit); vaidarbhyaḥ — daughters of Vidarbha; patnyaḥ — wives; tisraḥ — three; su-sammatāḥ — very pleasing and suitable; jaghnuḥ — killed; tyāga-bhayāt — fearing rejection; putrān — their sons; na anurūpāḥ — not exactly like the father; iti — like this; īrite — considering.
Translation: 
O King Parīkṣit, Mahārāja Bharata had three pleasing wives, who were daughters of the King of Vidarbha. When all three of them bore children who did not resemble the King, these wives thought that he would consider them unfaithful queens and reject them, and therefore they killed their own sons.