Doubt reg enoxparin injection

Patient: My wife aged 33 is in the first trimester (2nd child). she has been directed to have injection Enoxparin 0.6mg for 100 days. she has already been injected for 30 days. her apTT factor is 37.2 secs, in what way this injection is related to pregnancy? in what way this will help the foetus and the mother? is it essential to for her to continue with the injection? she is hypothyroidic and is presently having 87.5 mg of thyronorm. plz clarify me