( ( Her ( last ( menstrual period ) ) ) ( ( was ( ( ( approximately 6 ) weeks ) ago ) ) . ) )
(ROOT (S (NP (PRP$ Her) (JJ last) (JJ menstrual) (NN period)) (VP (VBD was) (ADVP (NP (QP (RB approximately) (CD 6)) (NNS weeks)) (RB ago))) (. .)))
Her last menstrual period was approximately 6 weeks ago.
(ROOT (S (NP (DT The) (JJ fetal) (NN period)) (VP (VBZ lasts) (NP (NP (QP (RB approximately) (CD 30)) (NNS weeks)) (NP (NNS weeks)))) (. .)))