In mother's milk.
1	In	in	ADP	E	_	4	case	_	_
2	mother	mother	NOUN	S	Number=Sing	4	nmod	_	SpaceAfter=No
3	's	's	PART	PART	_	2	case	_	_
4	milk	milk	NOUN	S	Number=Sing	0	root	_	SpaceAfter=No
5	.	.	PUNCT	FS	_	4	punct	_	_
