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Clinical Endocrinology

FERTILITY AFTER CHILDBIRTH: CHANGES IN SERUM GONADOTROPHIN LEVELS IN BOTTLE AND BREAST FEEDING WOMEN

Authors

  • ANNA GLASIER,

    Corresponding author
    1. MRC Unit of Reproductive Biology & Department of Obstetrics & Gynaecology, University of Edinburgh, Centre for Reproductive Biology, 37 Chalmers Street, Edinburgh EH3 9EW
      Dr Anna Glasier, Department of Obstetrics and Gynaecology, University of Edinburgh, 37 Chalmers St, Edinburgh EH3 9EW.
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  • A. S. McNEILLY,

    1. MRC Unit of Reproductive Biology & Department of Obstetrics & Gynaecology, University of Edinburgh, Centre for Reproductive Biology, 37 Chalmers Street, Edinburgh EH3 9EW
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  • P. W. HOWIE

    1. MRC Unit of Reproductive Biology & Department of Obstetrics & Gynaecology, University of Edinburgh, Centre for Reproductive Biology, 37 Chalmers Street, Edinburgh EH3 9EW
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    • *

      Department of Obstetrics & Gynaecology, University of Dundee Medical School, Ninewells Hospital, Dundee DD1 9SY.


Dr Anna Glasier, Department of Obstetrics and Gynaecology, University of Edinburgh, 37 Chalmers St, Edinburgh EH3 9EW.

SUMMARY

Changes in basal serum gonadotrophin levels during the resumption of ovarian activity post partum have been studied longitudinally in breast and bottle feeding mothers. On the basis of urinary steroid levels, ovarian activity was classified as showing complete suppression, follicular activity only, deficient luteal phases or normal menstrual cycles. Complete suppression of ovarian activity during lactation was associated with normal levels of FSH but low levels of LH. The resumption of follicular development was not accompanied by any increase in levels of either LH or FSH when compared with the phase of complete suppression and this pattern persisted during menstrual cycles characterized by deficient luteal phase progesterone secretion. Basal LH levels did not rise to normal levels during lactation until the resumption of normal ovulatory cycles. FSH secretion remained at a level comparable with the follicular phase of normal ovulatory cycles throughout the post partum period.

In mothers who did not breast feed, LH levels rose more rapidly than in breast feeding mothers and had returned to within normal limits by three weeks post partum. At 4 weeks post partum FSH levels were lower in bottle feeding mothers than in breast feeders probably in response to the early rise in oestrogen levels among bottle feeders.

These results suggest that decreased LH but not FSH secretion may be important in maintaining infertility associated with breast feeding. The absence of any change in LH or FSH at the onset of follicular development suggests that an alteration in the sensitivity of the ovary to gonadotrophins or in the pattern of gonadotrophin secretion may be involved in the observed patterns of post partum ovarian activity during lactation.

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