Ann Wauters has gotten the most career boards by a player younger than 21, with 237 rebounds.

Interpreted as:

most rebounds before turning 21 years old by a player

	NAME	REB	GP	MPG	PPG	RPG	APG	SPG	BPG	FGM	FGA	FG%	3PM	3PA	3P%	FTM	FTA	FT%	TS%	OREB	DREB	TPG	MIN	PTS	AST	STL	BLK	TOV	PF	+/-
1	Ann Wauters A. Wauters	237	55	21.8	7.8	4.3	1.3	0.7	0.7	3.0	5.5	54.3	0.0	0.1	0.0	1.9	2.4	77.4	59.8	1.4	2.9	2.0	1,196	429	69	37	37	111	126	+183
2	Maria Stepanova M. Stepanova	202	52	13.1	6.0	3.9	0.6	0.3	1.4	2.3	5.0	47.1	0.0	0.0	50.0	1.3	2.1	62.7	51.1	1.5	2.4	1.0	681	314	31	16	73	52	115	+67
3	Dominique Malonga D. Malonga	195	42	14.3	7.7	4.6	0.9	0.4	0.7	3.5	6.3	55.1	0.1	0.4	22.2	0.7	1.2	56.9	56.6	1.3	3.4	1.1	600	323	36	17	28	48	87	-20
4	Lauren Jackson L. Jackson	193	29	34.5	15.2	6.7	1.5	1.9	2.2	5.1	14.0	36.7	1.4	4.4	31.0	3.6	4.9	72.7	47.1	2.0	4.7	1.8	1,000	442	44	54	64	53	97	-56
5	Liz Cambage L. Cambage	156	33	20.0	11.5	4.7	0.5	0.8	0.9	4.1	7.9	51.1	0.0	0.2	0.0	3.4	4.3	79.4	58.6	1.6	3.1	2.4	659	380	17	28	29	79	95	-192
6	JiSu Park J. Park	134	57	10.2	1.9	2.4	0.7	0.3	0.4	0.8	2.4	34.1	0.0	0.1	0.0	0.3	0.5	56.7	36.8	0.6	1.7	0.5	579	109	40	15	24	30	77	-25
7	Awak Kuier A. Kuier	122	49	11.4	2.6	2.5	0.8	0.4	0.8	0.9	2.6	36.8	0.1	0.8	17.9	0.6	0.9	66.7	44.5	0.7	1.8	0.7	558	129	38	18	41	35	36	-35
8	Penny Taylor P. Taylor	112	32	17.5	7.2	3.5	1.4	1.1	0.3	2.7	7.0	38.2	0.7	2.3	30.1	1.1	1.4	78.3	46.9	1.1	2.4	1.2	560	230	44	35	11	38	46	+83
9	Quanitra Hollingsworth Q. Hollingsworth	110	34	12.8	4.8	3.2	0.1	0.4	0.2	1.5	3.5	41.7	0.0	0.0		1.9	2.7	70.3	51.2	1.4	1.9	1.0	434	164	5	12	8	34	65	-87
10	Emma Meesseman E. Meesseman	106	34	14.7	4.4	3.1	1.2	0.6	0.7	1.9	4.4	44.6	0.0	0.1	0.0	0.5	0.6	81.0	47.4	1.2	1.9	0.9	498	149	42	19	24	29	54	+67
11	Kristen Veal K. Veal	69	42	18.8	3.4	1.6	3.4	0.9	0.1	1.1	3.6	29.4	0.5	1.5	29.2	0.8	1.1	74.5	41.5	0.4	1.3	2.4	788	144	143	39	4	99	71	-152
12	Maria Kliundikova M. Kliundikova	60	26	8.8	4.4	2.3	0.5	0.4	0.5	1.9	3.6	53.2	0.2	0.6	37.5	0.3	0.5	69.2	57.7	0.7	1.6	0.6	228	115	12	11	14	15	48	+10
13	Svetlana Abrosimova S. Abrosimova	48	9	27.6	8.3	5.3	1.3	1.4	0.1	2.7	7.9	33.8	0.4	2.2	20.0	2.6	3.4	74.2	44.3	1.8	3.6	2.2	248	75	12	13	1	20	19	-39
14	Mwadi Mabika M. Mabika	48	16	17.4	7.0	3.0	1.4	1.4	0.3	3.0	7.1	42.1	0.4	1.9	22.6	0.6	1.1	50.0	45.9	1.3	1.8	1.6	278	112	22	22	4	25	40	-39
15	Sandrine Gruda S. Gruda	32	11	13.9	5.4	2.9	0.6	0.5	0.8	2.3	5.1	44.6	0.0	0.0		0.8	1.3	64.3	47.5	1.0	1.9	1.1	152	59	7	6	9	12	18	+21
16	Jade Melbourne J. Melbourne	31	21	12.1	3.2	1.5	1.4	0.5	0.0	1.1	2.7	41.1	0.1	0.8	17.6	0.9	1.1	75.0	50.3	0.3	1.2	0.9	253	67	29	11	1	19	36	-4
17	Sika Koné S. Koné	30	12	8.5	3.4	2.5	0.3	0.3	0.0	1.1	2.2	50.0	0.0	0.2	0.0	1.3	1.5	83.3	60.4	1.0	1.5	1.0	102	41	4	3	0	12	17	-27
18	Ezi Magbegor E. Magbegor	20	9	13.0	6.9	2.2	0.4	0.3	0.9	3.1	4.7	66.7	0.1	0.1	100.0	0.6	1.1	50.0	66.8	1.1	1.1	0.3	117	62	4	3	8	3	13	+40
19	Iliana Rupert I. Rupert	18	6	16.2	6.5	3.0	0.8	0.3	0.0	2.5	4.7	53.6	1.3	3.0	44.4	0.2	0.3	50.0	67.5	1.0	2.0	0.3	97	39	5	2	0	2	14	-22
20	Iziane Castro Marques I. Castro Marques	17	19	9.4	3.5	0.9	0.4	0.4	0.0	1.3	3.8	33.3	0.1	0.9	5.9	0.9	1.3	68.0	39.8	0.4	0.5	0.9	178	66	7	7	0	18	22	+17
21	Anastasiia Olairi Kosu A. Olairi Kosu	15	21	3.8	1.7	0.7	0.2	0.0	0.2	0.6	1.4	44.8	0.0	0.1	0.0	0.4	0.7	60.0	49.2	0.5	0.2	0.3	80	35	5	1	4	7	9	+35
22	Han Xu H. Xu	15	18	7.9	3.0	0.8	0.1	0.2	0.2	1.3	3.2	41.4	0.3	0.6	50.0	0.1	0.1	50.0	45.9	0.1	0.7	0.1	143	54	2	3	4	2	6	+21
23	Erika de Souza E. de Souza	14	11	3.8	1.1	1.3	0.2	0.3	0.0	0.5	1.3	35.7	0.0	0.0		0.2	0.9	20.0	32.6	0.7	0.5	0.5	42	12	2	3	0	6	14	-32
24	Astou Ndour-Fall A. Ndour-Fall	9	8	4.4	2.1	1.1	0.0	0.0	0.3	1.0	2.4	42.1	0.1	0.4	33.3	0.0	0.0		44.7	0.5	0.6	0.4	35	17	0	0	2	3	4	-4
25	Bernadette Ngoyisa B. Ngoyisa	5	7	1.7	0.9	0.7	0.0	0.0	0.3	0.4	0.7	60.0	0.0	0.0		0.0	0.0		60.0	0.1	0.6	0.0	12	6	0	0	2	0	2	0