Abstract
In almost all mammals lactation, or more correctly the suckling stimulus, induces a period of infertility designed to provide the optimal birth spacing for survival of the offspring. The duration of lactational infertility depends on the sucking activity of the young with little evidence to support a role for nutritional status. Suckling disrupts the normal pulsatile pattern of hypothalamic gonadotrophin releasing hormone (GnRH)2secretion resulting in reduced LH secretion from the pituitary. Secretion of FSH returns to its normal cyclic pattern early in lactation and ovarian follicles may develop under its influence. However, until suckling declines, the follicles fail to secrete amounts of estradiol adequate to stimulate an LH surge and ovulation. The suckling stimulus may affect GnRH secretion by affecting prolactin, opiate and dopaminergic tone in the hypothalamus but no unifying mechanism has yet been proposed convincingly. The birth spacing effects of breastfeeding in women have a profound effect on infant well-being, and breastfeeding still prevents more pregnancies than all forms of artificial contraception.
Similar content being viewed by others
REFERENCES
P. W. Howie and A. S. McNeilly (1982). Effect of breastfeeding patterns on human birth intervals. J. Reprod. Fertil. 65:545–557.
S. Thapa, R. V. Short, and M. Potts (1988). Breast feeding, birth spacing and their effects on child survival. Nature 335:679–682.
L. M. GrummerStrawn (1996). The effect of changes in population characteristics on breastfeeding trends in fifteeen developing countries. Int. J. Epidemiol. 25:94–102.
R. V. Short (1993). Lactational infertility in family planning. Ann. Med. 25:175–180.
A. S. McNeilly (1993). Lactational amenorrhoea, In J. D. Veldhuis (ed.), Endocrinology and Metabolism Clinics of North America. Neuroendocrinology II, W. B. Saunders Company, Philadelphia pp. 59–73.
A. S. McNeilly, P. W. Howie, and M. J. Houston (1981). Relationship of feeding patterns, prolactin and resumption of ovulation postpartum. In: G. I. Zatuchni, M. H. Labbok and J. J. Sciarra (eds.), Research Frontiers in Fertility, Harper Row, Mexico City, pp. 102–116.
K. I. Kennedy, R. Rivero, and A. S. McNeilly (1989). Consensus statement on the use of breastfeeding as a family planning method. Contraception 39:477–496.
M. H. Labbok, A. Pérez, V. Valdés, F. Sevilla, K. Wade, V. H. Laukaran et al.(1994). The lactational amenorrhea method (LAM): a postpartum introductory family planning method with policy and program implications. Adv. Contracept. 10:93–109.
K. I. Kennedy, M. H. Labbok, and P. F. A. Van Look (1996). Consensus statement: lactational amenorrhoea method for family planning. Int. J. Gynaecol. 54:55–57.
P. F. A. Van Look (1996). Lactational amenorrhoea method for family planning. Br. Med. J. 331:893.
A. S. McNeilly (1994). Suckling and the control of gonadotropin secretion. In E. Knobil and J. Neill (eds.), The Physiology of Reproduction, Raven Press, New York, Chap. 60, pp. 1179–1212.
A. S. McNeilly, C. C. K. Tay, and A. Glasier (1994). Physiological mechanisms underlying lactational amenorrhoea. In K. L. Campbell and J. W. Wood (eds.), Human Reproductive Ecology; Interactions of Environment, Fertility and Behaviour. Annals of the New York Academy of Science709, pp. 145–155.
P. J. Illingworth and A. S. McNeilly (1997). Estrogens and progestogens in the postpartum period. In I.S. Fraser, R.P.S. Jansen, R. Lobo and M. Whitehead, (eds.), Guidelines to Estrogens and Progestogens in Clinical Practice, Churchill-Livingstone, London.
S. F. Lunn and A. S. McNeilly (1982). Failure of lactation to have a consistent effect on interbirth interval in the common marmoset (Callithrix jacchus jacchus). Folia. Primatol. 37,99–105.
A. Flynn, M. Docker, J. B. Brown, and K. I. Kennedy (1991). Ultrasonographic patterns of ovarian activity during breastfeeding. Am. J. Obstet. Gynecol. 165:2027–2031.
M. delaLastra and C. Llados (1977). Luteinizing hormone content of the pituitary gland in pregnant and nonpregnant women. J. Clin. Endocrinol. Metab. 44:921–923.
R. H. Gray, O. M. Campbell, H. A. Zacur, M. H. Labbok, and S. L. MacRae (1987). Postpartum return of ovarian activity in nonbreastfeeding women monitored by urinary assays. J. Clin. Endocrinol. Metab. 64:645–650.
A. S. McNeilly, P. W. Howie, M. J. Houston, A. Cook, and H. Boyle (1982). Fertility after childbirth: adequacy of post-partum luteal phases. Clin. Endocrinol. 17:609–615.
H. G. Burger, H. P. C. Hee, P. Mamers, M. Bangah, M. Zissimos, and P. I. McCloud (1994). Serum inhibin during lactation: relation to the gonadotrophins and gonadal steroids. Clin. Endocrinol. 41:771–777.
J. Kremer, L. A. Schellekens, M. Segers, C. Thomas, and R. Rolland (1994). Circulating inhibin levels in lactating and nonlactating women. Fertil. Steril. 62:1150–1156.
A. F. Glasier, A. S. McNeilly, and P. W. Howie (1984). Pulsatile secretion of LH in relation to the resumption of ovarian activity post partum. Clin. Endocrinol. 20:415–426.
W. C. Nunley, R. J. Urban, and W. S. Evans (1991). Preservation of pulsatile luteinizing hormone release during postpartum lactational amenorrhoea. J. Clin. Endocrinol. Metab. 73:629–636.
C. C. K. Tay, A. F. Glasier, and A. S. McNeilly (1992). The twenty-four hour pattern of pulsatile luteinizing hormone, follicle stimulating hormone and prolactin release during the first eight weeks of lactational amennorhoea in breastfeeding women. Hum. Reprod. 7:951–958.
M. E. Wise (1990). Gonadotropin-releasing hormone secretion during the postpartum anestrous period of the ewe. Biol. Reprod. 143:719–725.
S. R. Fox and M. S. Smith (1984). The suppression of pulsatile luteinizing hormone secretion during lactation. Endocrinology 115:2045–2051.
A. Glasier, A. S. McNeilly, and D. T. Baird (1986). Induction of ovarian activity by pulsatile infusion of LHRH in women with lactational amenorrhoea. Clin. Endocrinol. 24:243–252.
M. J. Zinaman, T. Cartledge, T. Tomai, P. Tippett, and G. R. Merriam (1995). Pulsatile GnRH stimulates normal cycle ovarian function in amenorrhoeic lactating postpartum women. J. Clin. Endocrinol. Metab. 80:2088–2093.
S. M. Moenter, A. Caraty, A. Locatelli, and F. J. Karsch (1991). Pattern of gonadotropin-releasing hormone (GnRH) secretion leading up to ovulation in the ewe: existence of a preovulatory GnRH surge. Endocrinology 129:1175–1182.
P. J. Illingworth, J. E. V. Seaton, C. McKinlay, V. Reid-Thomas, and A. S. McNeilly (1995). Low dose transdermal oestradiol supresses gonadotrophin secretion in breastfeeding women. Hum. Reprod. 10:1671–1677.
K. M. Kurz, J. P. Habicht, and K. M. Rasmussen (1991). Influences of maternal nutrition on lactation and length of postpartum anenorrhea. J. Trop. Pediatr. 37:15–18.
P. Lewis, J. Brown, and M. Renfree (1985). The resumption of ovulation and menstruation in a well-nourished population of women breastfeeding for an extended period of time. Fertil. Steril. 55:529–536.
P. J. Illingworth, R. T. Jung, P. W. Howie, et al.Diminution of energy expenditure during lactation. Br. Med. J. 292:437–441.
A. S. I. Loudon, A. S. McNeilly, and J. A. Milne (1983). Nutrition and lactational control of fertility in red deer. Nature 302:145–147.
P. Ramachandran (1992). Nutrition and its influence on the mother-child dyad. In Nutrition and Population Link—Breastfeeding, Family Planning and Child Health. United Nations Administrative Committee on Coordination, Subcommittee on Nutrition. Nutrition Policy Discussion Paper No. 11, Chap. 5, pp. 47–54.
I. A. Barash, C. C. Cheung, D. S. Weigle, H. Ren, E. B. Kabigting, J. L. Kuijper, D. K. Clifton, and R. A. Steiner (1996). Leptin is a metabolic signal to the reproductive system. Endocrinology 137:3144–3147.
J. D. Neill and G. M. Nagy (1994). Prolactin secretion and its control. In E. Knobil and J. D. Neill (eds.), The Physiology of Reproduction, Second Edition, Raven Press, New York, pp. 1833–1860.
A. S. McNeilly (1987). Prolactin and the control of gonadotrophin secretion. J. Endocrinol. 115:5.
L. A. Arbogast and J. Voogt (1996). The responsiveness of tuberoinfundibular dopaminergic neurons to prolactin feedback is diminished between early lactation and midlactation in the rat. Endocrinology 137:47–54.
P. Callahan, M. H. Baumann, and J. Rabii (1996). Inhibition of tuberoinfundibular dopaminergic neural activity during suckling: involvement of μ and K opiate receptor subtypes. J. Neuroendocrinol. 8:771–776.
H. J. Wang, G. E. Hoffman, and M. S. Smith (1994). Suppressed tyrosine hydroxylase gene expression in the tuberoinfundibular dopaminergic system during lactation. Endocrinology 133:1657–1663.
C. C. K. Tay, A. F. Glasier, and A. S. McNeilly (1993). Effect of antagonists of dopamine and opiates on the basal and GnRH-induced secretion of luteinizing hormone, follicle stimulating hormone and prolactin during lactational amenorrhoea in breastfeeding women. Hum. Reprod. 8:532–539.
K. Gordon, G. D. Hodgen, and D. W. Richardson (1992). Postpartum lactational anovulation in a non-human primate (Macaca fascicularis): endogenous opiate mediation of suckling-induced hyperprolactinaemia. J. Clin. Endocrinol. Metab., 75:59–67.
M. Mattioli, F. Contem, G. Graleatim, et al.(1986). Effect of naloxone on plasma concentrations of prolactin and LH in lactating sows. J. Reprod. Fert. 76:167–73.
G. Lodico, I. Stopelli, G. Delitala, et al.(1983). Effects of naloxone infusion on basal and breast stimulated prolactin secretion in puerperal women. Fert. Steril. 40:600–603.
F. Derensis, J. R. Cosgrove, and G. R. Foxcroft (1993). Luteinizing-hormone and prolactin responses to naloxone vary with stage of lactation in the sow. Biol. Reprod. 48:970–976.
S. Chiu and P. M. Wise (1994). Prolactin receptor mRNA localization in the hypothalamus by in situ hybridization. J. Neuroendocrinol. 6:191–199.
T. Sugiyama, H. Minoura, N. Toyoda, K. Sakaguchi, M. Tanaka, S. Sudo, and K. Nakashima (1996). Pup contact induces the expression of long form prolactin receptor mRNA in the brain of female rats: Effects of ovariectomy and hypophysectomy on receptor gene expression. J. Endocrinol. 149:335–340.
L. Milenkovic, G. D. D'Angelo, P. A. Kelly, and R. I. Weiner (1994). Inhibition of gonadotropin releasing-hormone release by prolactin from GT1 neuronal cell lines through prolactin receptors. Proc. Natl. Acad. Sci. U.S.A. 91:1244–1247.
C. C. K. Tay, A. F. Glasier, and A. S. McNeilly (1996). Twenty-four hour patterns of prolactin secretion during lactation and the relation to suckling and the resumption of fertility in breastfeeding women. Hum. Reprod. 11:950–955.
S. Diaz, H. Cardenas, and A. Brandeis (1991). Early differences in the endocrine profile of long and short lactational amenorrhoea. J. Clin. Endocrinol. Metab. 72:196–201.
J. F. Stallings, C. M. Worthman, C. Panterbrick, and R. J. Coates (1996). Prolactin response to suckling and maintenance of postpartum amenorrea among intensively breastfeeding Nepali women. Endocrinol. Res. 22:1–28.
C. R. Prieto, H. Cardenas, A. M. Salvatierra, C. Boza, C. G. Montes, and H. B. Croxatto (1996). Sucking pressure and its relationship to milk transfer during breastfeeding in humans. J. Reprod. Fertil. 108:69–74.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
McNeilly, A.S. Lactation and Fertility. J Mammary Gland Biol Neoplasia 2, 291–298 (1997). https://doi.org/10.1023/A:1026340606252
Issue Date:
DOI: https://doi.org/10.1023/A:1026340606252