Regulation of Post-Partum Fertility in Lactating Mammals

McNeilly, Alan S.; Forsyth, Isabel A.; McNeilly, J. R.

doi:10.1007/978-94-011-1286-4_11

Cited by 7 publications

(6 citation statements)

References 602 publications

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“…One possible mechanism would be the impact that 396 social stress has on the mammalian female menstrual system (and hence fecundity), the 397 endocrinology of which is now well understood (Abbott 1984;Abbott et al 1984;Gordon et 398 al. 1992;McNeilly et al 1994;McNeilly 2001a,b;von Borrel et al 2007;Son et al 2012;Iwasa et al 2017; see also Wasser & Barash 1983;Huchard & Cowlishaw 2011). To confirm this in the present case, endocrinological studies of gorillas 401 and chimpanzees are needed.…”

Section: Discussionsupporting

confidence: 52%

Fertility as a constraint on group size in African great Apes

Dunbar

2019

Biological Journal of the Linnean Society

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Gorillas and chimpanzees live in social groups of very different size and structure. Here I test the hypothesis that this difference might reflect the way fertility maps onto group demography as it does in other Catarrhines. For both genera, birth rates and the number of surviving offspring per female are quadratic (or ∩-shaped) functions of the number of adult females in the group, and this is independent of environmental effects. The rate at which fertility declines ultimately imposes a constraint on the size of social groups that can be maintained in both taxa. The differences in group size between the two genera seem to reflect a contrast in the way females buffer themselves against this cost. Gorillas do this by using males as bodyguards, whereas chimpanzees exploit fission–fusion sociality to do so. The latter allows chimpanzees to live in much larger groups without paying a fertility cost (albeit at a cognitive cost).

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Section: Discussionsupporting

confidence: 52%

Fertility as a constraint on group size in African great Apes

Dunbar

2019

Biological Journal of the Linnean Society

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“…There is some evidence to suggest that, independently of any glucocorticoid involvement, endorphin up-regulation in response to any social or physical stress inhibits the GnRH, thereby blocking the LH surge needed to precipitate ovulation (Howlett and Rees, 1986;Ziegler et al, 1990;Gordon et al, 1992;McNeilly et al, 1994;Kalra and Kalra, 1996;McNeilly, 2001;Son et al, 2012;Iwasa et al, 2017). In rats, even the stress induced by being physically constrained for short periods can be sufficient to block the cyclic release of gonadotrophins necessary for ovulation (Euker and Riegle, 1973).…”

Section: A Mechanism For Reproductive Suppressionmentioning

confidence: 99%

The Infertility Trap: The Fertility Costs of Group-Living in Mammalian Social Evolution

Dunbar

Shultz

2021

Front. Ecol. Evol.

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Mammal social groups vary considerably in size from single individuals to very large herds. In some taxa, these groups are extremely stable, with at least some individuals being members of the same group throughout their lives; in other taxa, groups are unstable, with membership changing by the day. We argue that this variability in grouping patterns reflects a tradeoff between group size as a solution to environmental demands and the costs created by stress-induced infertility (creating an infertility trap). These costs are so steep that, all else equal, they will limit group size in mammals to ∼15 individuals. A species will only be able to live in larger groups if it evolves strategies that mitigate these costs. We suggest that mammals have opted for one of two solutions. One option (fission-fusion herding) is low cost but high risk; the other (bonded social groups) is risk-averse, but costly in terms of cognitive requirements.

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“…Interestingly, the finding that progesterone is not elevated in mice during lactation may be a useful characteristic to model lactation in humans, as humans similarly do not have elevated progesterone levels during lactation ( 77 ). Data both from women and nonhuman primates show that duration of lactational infertility is correlated to the levels of prolactin produced ( 44 , 78-80 ), with women with higher concentrations of prolactin having longer-lasting lactational infertility ( 81-84 ).…”

Section: Discussionmentioning

confidence: 99%

Mechanisms of Lactation-induced Infertility in Female Mice

et al. 2023

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Lactation in mammals is associated with a period of infertility, which serves to direct maternal metabolic resources towards caring for the newborn offspring rather than supporting another pregnancy. This lactational infertility is characterized by reduced pulsatile luteinizing hormone (LH) secretion and lack of ovulation. The mechanisms mediating suppression of LH secretion during lactation are unclear. There are potential roles for both hormonal cues such as prolactin and progesterone, and pup-derived cues such as suckling, on the inhibition of reproduction. To enable future studies using transgenic animals to investigate these mechanisms, in the present study our aim was to characterize lactational infertility in mice, and to investigate the effect of removing pup-derived cues on LH secretion, time to ovulation and kisspeptin immunoreactivity. We firstly confirmed that C57BL/6J mice experience prolonged anestrus during lactation, which is dependent on establishment of lactation, as removal of pups on the day of parturition led to immediate resumption of pulsatile LH secretion and normal estrous cycles. Once lactation is established, however, the lactational anestrus persisted for several days even after premature removal of pups. Pharmacological suppression of prolactin following premature weaning significantly reduced this period of lactational infertility. Progesterone does not appear to play a significant role in the suppression of fertility during lactation in mice, as levels measured during lactation were not different from non-pregnant mice. These data suggest that prolactin plays a key role in mediating anestrus during early lactation in mice, even in the absence of the suckling stimulus.

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Regulation of Post-Partum Fertility in Lactating Mammals

Cited by 7 publications

References 602 publications

Fertility as a constraint on group size in African great Apes

Fertility as a constraint on group size in African great Apes

The Infertility Trap: The Fertility Costs of Group-Living in Mammalian Social Evolution

Mechanisms of Lactation-induced Infertility in Female Mice

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