title: Luteinizing hormone pulsatile release and the length of lactational amenorrhoea.
abstract: The pattern of luteinizing hormone (LH) pulsatile release and the mean concentrations of follicle-stimulating hormone, oestradiol and progesterone were studied in nursing and non-nursing women. Blood samples were drawn at 5 min intervals between 10:00 and 14:00 h and between 22:00 and 02:00 h at months 3-4, 5-6, 7-8 and 9-10 postpartum in nursing women and in the follicular phase in non-nursing women. In nursing women, mean LH concentrations at months 3-4 were significantly lower than in non-nursing cycling women only in the subgroup which subsequently experienced > 6 months of lactational amenorrhoea, although all were fully nursing with a similar suckling frequency. LH pulses in plasma were found at all times in nursing women. There were no significant differences in the frequency (about four pulses every 4 h), amplitude or duration of LH pulses related to the duration of amenorrhoea, nor did these parameters vary significantly between amenorrhoeic or cycling nursing women and non-nursing women. Nursing amenorrhoeic women exhibited a normal frequency of LH pulse well in advance of the resumption of the first post-partum menses, suggesting that mechanisms other than the suppression of the gonadotrophin-releasing hormone pulse generator intervened in the inhibition of ovarian function during lactation.
authors.affiliation: Laboratorio de Endocrinología, Facultad de Ciencias Biológicas, P. Universidad Católica de Chile, Santiago, Chile.
authors.forename: S
authors.initials: S
authors.lastname: Díaz
authors.forename: H
authors.initials: H
authors.lastname: Cárdenas
authors.forename: A
authors.initials: A
authors.lastname: Zepeda
authors.forename: A
authors.initials: A
authors.lastname: Brandeis
authors.forename: V
authors.initials: V
authors.lastname: Schiappacasse
authors.forename: P
authors.initials: P
authors.lastname: Miranda
authors.forename: M
authors.initials: M
authors.lastname: Serón-Ferré
authors.forename: H B
authors.initials: HB
authors.lastname: Croxatto
mesh_terms: D000328:Adult; D000568:Amenorrhea / Q000209:etiology / Q000503:physiopathology*; D001942:Breast Feeding; D016022:Case-Control Studies; D004958:Estradiol / Q000378:metabolism; D005069:Evaluation Studies as Topic; D005260:Female; D005640:Follicle Stimulating Hormone / Q000378:metabolism; D005500:Follow-Up Studies; D006801:Humans; D007774:Lactation / Q000502:physiology*; D007986:Luteinizing Hormone / Q000378:metabolism*; D049590:Postpartum Period / Q000502:physiology*; D011374:Progesterone / Q000378:metabolism; D012016:Reference Values; D012636:Secretory Rate / Q000502:physiology; D013997:Time Factors
chemical_list: D011374:Progesterone; D004958:Estradiol; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone