Title: Fertility after childbirth: changes in serum gonadotropin levels in bottle and breast feeding women.

POPLINE Document Number: 018606

Author(s):

Glasier A
McNeilly AS
Howie PW

Source citation:

Clinical Endocrinology, 1983 Oct;19(4):493-501.

Abstract:

Changes in basal serum gonadotropin levels were analyzed in relation to level of ovarian activity in a longitudinal study of 24 breastfeeding and 7 nonlactating women ages 21-40 years. Ovarian activity was categorized as showing complete suppression, follicular activity only, inadequate luteal phases, or normal menstrual cycle. Resumption of follicular activity, menstruation, and ovulation was significnatly delayed (p<0.001) among lactating compared with nonlactating women. The 1st postpartum menstrual period was preceded by ovulation in 13 (55%) of lactating women. Complete suppression of ovarian activity during lactation was associated with normal levels of follicle stimulating hormone (FSH) but low levels of luteinizing hormone (LH). Resumption of follicular development was not accompanied by increased levels of either gonadotropin. LH levels were significantly (p<0.01) lower at 4 weeks postpartum than at any other time, but showed significant increases by 8 weeks postpartum and remained unchanged thereafter until normal ovulatory cycles resumed. FSH secretion remained at a level comparable with the follicular phase of normal ovulatory cycles throughout the postpartum period. Nonlactating women did not demonstrate change in mean basal LH levels as ovarian activity resumed. Mean basal FSH levels were significantly (p<0.05) lower when ovarian activity was suppressed than during the follicular phase of normal cycles. In addition, mean FSH levels during absent or reduced ovarian activity were lower at 4 weeks postpartum than they were in lactating women. However, total estrogen levels were significantly (p<0.01) higher among nonlactating women at this time. These results confirm earlier reports that FSH levels increase after pregnancy and remain within the normal range of menstrual cycles in the postpartum period, while LH levels increase to and remain at the lower limit of normal. They suggest that decreased LH but not FSH secretion may be important in maintaining the infertility associated with lactation. The absence of changes in LH or FSH levels at the onset of follicular development suggests that an alteration in the sensitivity of the ovary to gonadotropins or in the pattern of gonadotropin secretion may be involved in postpartum ovarian activity patterns observed during lactation.

Keywords:

Clinical Research
Follicle Stimulating Hormone
Luteinizing Hormone
Gonadotropins, Pituitary
Gonadotropins
Hormones
Lactation
Puerperium
Ovulation
Menstrual Cycle
Menstruation
Research Methodology
Endocrine System
Physiology
Biology
Maternal Physiology
Reproduction