( ( ( ( ( Estrogens ( ( are ( responsible ( for ( breast development ) ) ) ) ( at puberty ) ) ) , ) and ) ( ( each month ) ( , ( they ( cause ( ( the lining ) ( of ( the ( uterus ( to ( thicken ( in ( anticipation ( of pregnancy ) ) ) ) ) ) ) ) ) ) ) ) ) ) . )
(ROOT (S (S (NP (NNS Estrogens)) (VP (VBP are) (ADJP (JJ responsible) (PP (IN for) (NP (NN breast) (NN development)))) (PP (IN at) (NP (NN puberty))))) (, ,) (CC and) (S (NP (DT each) (NN month)) (, ,) (NP (PRP they)) (VP (VBP cause) (NP (NP (DT the) (NN lining)) (PP (IN of) (NP (DT the) (NN uterus) (S (VP (TO to) (VP (VB thicken) (PP (IN in) (NP (NP (NN anticipation)) (PP (IN of) (NP (NN pregnancy))))))))))))) (. .)))
Estrogens are responsible for breast development at puberty, and each month, they cause the lining of the uterus to thicken in anticipation of pregnancy.
(ROOT (S (NP (NNP Estrogen)) (VP (VBZ causes) (NP (NP (DT the) (NNS changes)) (PP (IN of) (NP (NN puberty))))) (. .)))