Inclusion Criteria:  Participant is less than 9 years old for girls and less than 10 years old for boys at initiation of triptorelin treatment or at the time of signing the informed consent. Participant must present evidence of CPP documented by: Onset of development of secondary sex characteristics (breast development in girls or testicular enlargement in boys according to the Tanner method: Stage II) before the age of 8 years in girls and 9 years in boys. Pubertal response of LH to GnRH stimulation test (stimulated peak LH ≥6 IU/L) in both sexes. Difference between bone age (BA) and CA >1 year. Girls with Tanner staging ≥2 for breast development and who have enlarged uterine length and/or ovarian volume and several follicles with diameter >4 mm in the ovary observed by pelvic type B ultrasound at the Screening visit; boys who have testicular volume ≥4 mL observed by testicular orchidometer at the Screening visit. Girls who have already had menophania/menarche must have a negative highly sensitive (urine) pregnancy test as required by local regulations within 24 hours before the first dose of study intervention and should not be at risk of pregnancy throughout the study period.  Exclusion Criteria:  Gonadotropin-independent (peripheral) precocious puberty: extrapituitary secretion of gonadotropins or gonadotropin-independent gonadal or adrenal sex steroid secretion. Non-progressing isolated premature thelarche. Presence of an unstable intracranial tumour or an intracranial tumour requiring neurosurgery or cerebral irradiation. Participants with hamartomas not requiring surgery are eligible. Prior or current therapy with a GnRHa (Gonadotropin-releasing Hormone Agonist) , medroxyprogesterone acetate, growth hormone or insulin-like growth factor 1 (IGF 1).Use of anticoagulants (heparin and coumarin derivatives) within the 2 weeks prior to the Screening visit.