Pituitary-ovarian axis during lactational amenorrhoea. I. Longitudinal assessment of follicular growth, gonadotrophins, sex steroids and inhibin levels before and after recovery of menstrual cyclicity.
BACKGROUND
Comparisons of follicular development and hormonal profile in the same women during and after lactational amenorrhoea (LA) are scarce. We report follicular growth, pituitary and ovarian hormone serum levels in the same women during LA and in follicular phases after resumption of menstrual cyclicity.


METHODS
Serum samples were obtained from 10 women during LA between days 60 and 89 post-partum and between days 1 and 4 (early follicular phase; EFP) and 7 and 10 (mid-follicular phase; MFP) of the second and third cycles after LA.


RESULTS
The number of follicles >3 mm and diameter of the largest follicle were significantly higher during LA when compared to EFP and MFP. Serum levels of inhibin B were similar in LA and EFP and increased significantly in MFP. Pro-alphaC was significantly higher in EFP than in LA and MFP. Estradiol was similar during all stages. In comparison with EFP and MFP, LA is associated with higher prolactin levels, normal or slightly elevated gonadotrophins and increased number and size of follicles without a parallel increase in estradiol, inhibin B and Pro-alphaC.


CONCLUSIONS
During LA, there is a profound dissociation between follicular growth and follicular endocrine activity, which suggests an alteration in the stimulus-response relationship at the follicular level.
Velasquez
E V
EV
Instituto Chileno de Medicina Reproductiva, José Ramón Gutiérrez 295, Departamento 3, e Instituto Milenio de Biología Fundamental y Aplicada, Santiago, Chile.
Trigo
R V
RV
Creus
S
S
Campo
S
S
Croxatto
H B
HB
D000568:Amenorrhea / Q000097:blood*; D005260:Female; D012739:Gonadal Steroid Hormones / Q000097:blood*; D006062:Gonadotropins / Q000097:blood; D006065:Gonadotropins, Pituitary / Q000097:blood*; D006801:Humans; D007265:Inhibins / Q000097:blood*; D007774:Lactation / Q000097:blood; D008137:Longitudinal Studies; D008597:Menstrual Cycle / Q000097:blood; D006080:Ovarian Follicle / Q000000981:diagnostic imaging / Q000254:growth & development* / Q000378:metabolism; D010902:Pituitary Gland / Q000502:physiology; D049590:Postpartum Period / Q000097:blood; D014463:Ultrasonography
D012739:Gonadal Steroid Hormones; D006062:Gonadotropins; D006065:Gonadotropins, Pituitary; D007265:Inhibins