Female reproductive development: A hazards model analysis

Foster, Andrew D.; Menken, Jane; Chowdhury, A. I.

doi:10.1080/19485565.1986.9988638

Cited by 11 publications

(9 citation statements)

References 9 publications

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“…In one study (Apter and Vihko, 1983;Vihko and Apter, 1984) of Finnish girls, later age at menarche was correlated with a protracted period of adolescent subfecundity, which, if characteristic of adolescents at high altitude, could reduce total lifetime fertility compared to low altitude populations having a comparable median age at first sexual intercourse. However, other studies (MacMahon et al, 1982;Foster et al, 1986) have found no such correlation; hence any delay in maturation at high altitude cannot be assumed to result in prolonged adolescent subfecundity having demographic significance.…”

Section: Age At Menarchementioning

confidence: 89%

The Proximate Determinants of Fertility in Populations Exposed to Chronic Hypoxia

Vitzthum

Wiley

2003

High Altitude Medicine & Biology

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It has been hypothesized that hypoxia reduces fertility, but comparative studies of high and low altitude populations have been unable to verify or refute this proposal because it is difficult to control for the behavioral and sociocultural factors that may also either underlie fertility differentials or compensate for physiological changes caused by varying partial pressure of oxygen. Taken collectively, estimates of fertility in populations exposed to chronic hypoxia range widely and do not suggest any reproductive patterns specific to high altitude. Here we review the available data from the Andes and the Himalaya on the proximate determinants of fertility, that set of factors through which any and all environmental, behavioral, and sociocultural factors must act to influence fertility levels. Although hypoxia could potentially affect some of these factors, there is no unequivocal evidence that this occurs in human populations indigenous to high altitude. At this time, it appears that local variations in infant feeding beliefs and practices, often coupled with prolonged breast-feeding, play a major role in determining fertility variation in Andean populations. In the Himalaya, large numbers of adults are not in sanctioned sexual unions as a consequence of polyandrous marriage practices and religious celibacy. The absence of a clear negative effect of hypoxia on fertility in populations indigenous to high altitude, even though migrants report reproductive difficulties, argues that these populations have adapted to the conditions at high altitude. The experimental and clinical evidence presented in this issue suggests proximate mechanisms by which such adaptation, shaped by natural selection and developmental processes, is possible.

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Section: Age At Menarchementioning

confidence: 89%

The Proximate Determinants of Fertility in Populations Exposed to Chronic Hypoxia

Vitzthum

Wiley

2003

High Altitude Medicine & Biology

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“…Attention has been paid to the onset of menarche because it is a discreet event that marks the transition from partial to full reproductive potential (Altmann, 1986). Since the secular trend in age at menarche was first recognized, good and improved childhood nutrition and health have been associated with earlier menarche, and poor childhood conditions with delayed menarche (Foster et al, 1986;Gain, 1987;Eveleth and Tanner, 1990;Riley et al, 1993;Ellis, 2004). Although this assumption is still deeply embedded in the literature on puberty, growing evidence supports that suboptimal prenatal and childhood conditions also lead to early maturation (Cooper et al, 1996;Ibá ñ ez et al, 2000;Adair, 2001;Koziel and Jankowska, 2002;Coall and Chisholm, 2003).…”

Section: Discussionmentioning

confidence: 99%

“…Apter and Vihko (1983) find that girls who reach menarche at age 12.0-12.9 achieve 50% ovulatory cycles, which is considered normal adult function, 3.0 years after menarche. In contrast, girls who are 13.0 and older at first menses, achieve adult function 4.5 years after menarche (but see Foster et al, 1986). Mean populational differences in menarcheal age are negatively related to ovarian function as inferred from midluteal progesterone levels.…”

Section: Discussionmentioning

confidence: 99%

Early sexual maturity among Pumé foragers of Venezuela: Fitness implications of teen motherhood

Kramer

2008

American J Phys Anthropol

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Because humans have slow life histories, discussions of the optimal age at first birth have stressed the benefits of delayed reproduction. However, given the diversity of ecological, fertility, and mortality environments in which humans live, reproductive maturity is expected to be highly variable. This article uses reproductive histories to examine a pattern of early menarche and first birth among the Pume, a group of South American foragers. Age at menarche and first birth are constructed using both retrospective and cross-sectional data for females over the age of 10 (n = 83). The objectives are first to define these patterns and then discuss their reproductive consequences. On average, Pume girls reach menarche at age 12.9, and give birth to their first child at age 15.3-15.5 (retrospective and cross-sectional data, respectively). This populational average falls several years prior to what often is considered the human norm. Two questions are then considered. What are the infant mortality costs across a mother's reproductive career? How does surviving fertility vary with age at first birth? Results indicate that the youngest of first-time mothers (<14) are four times more likely to loose their firstborns than older first-time mothers (> or =17). Given parity-specific mortality rates, the optimal strategy to minimize infant mortality and maximize reproductive span is to initiate childbearing in the midteens. Women gain no additional advantage in surviving fertility by delaying childbearing until their late teens.

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“…In Finnish girls, menarcheal age and duration of adolescent subfecundity (i.e., age-associated risk of anovulation) was positively correlated (Apter and Vihko, 1983;Vihko and Apter, 1984) and, in a follow-up study in adulthood, age at menarche and follicular-phase (but not luteal phase) estradiol levels were negatively correlated (Apter et al, 1989). But two much larger studies found no evidence of such associations (MacMahon et al, 1982a;Foster et al, 1986). Progesterone, but not estrogen, was lower in ovulatory cycles from New Yorkers with an earlier menarcheal age (Westhoff et al, 1996).…”

Section: Dietary Composition Despite Vast Differences In Diets Mostmentioning

confidence: 91%

The ecology and evolutionary endocrinology of reproduction in the human female

Vitzthum

2009

American J Phys Anthropol

152

114

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Human reproductive ecology (HRE) is the study of the mechanisms that link variation in reproductive traits with variation in local habitats. Empirical and theoretical contributions from biological anthropology, physiology, and demography have established the foundation necessary for developing a comprehensive understanding, grounded in life history theory (LHT), of temporal, individual, and populational variation in women's reproductive functioning. LHT posits that natural selection leads to the evolution of mechanisms that tend to allocate resources to the competing demands of growth, reproduction, and survival such that fitness is locally maximized. (That is, among alternative allocation patterns exhibited in a population, those having the highest inclusive fitness will become more common over generational time.) Hence, strategic modulation of reproductive effort is potentially adaptive because investment in a new conception may risk one's own survival, future reproductive opportunities, and/or current offspring survival. The hypothalamic-pituitary-ovarian (HPO) axis is the principal neuroendocrine pathway by which the human female modulates reproductive functioning according to the changing conditions in her habitat. Adjustments of reproductive investment in a potential conception are manifested in temporal and individual variation in ovarian cycle length, ovulation, hormone levels, and the probability of conception. Understanding the extent and causes of adaptive and non-adaptive variation in ovarian functioning is fundamental to ascertaining the proximate and remote determinants of human reproductive patterns. In this review I consider what is known and what still needs to be learned of the ecology of women's reproductive biology, beginning with a discussion of the principal explanatory frameworks in HRE and the biometry of ovarian functioning. Turning next to empirical studies, it is evident that marked variation between cycles, women, and populations is the norm rather than an aberration. Other than woman's age, the determinants of these differences are not well characterized, although developmental conditions, dietary practices, genetic variation, and epigenetic mechanisms have all been hypothesized to play some role. It is also evident that the reproductive functioning of women born and living in arduous conditions is not analogous to that of athletes, dieters, or even the lower end of the ''normal range'' of HPO functioning in wealthier populations. Contrary to the presumption that humans have low fecundity and an inefficient reproductive system, both theory and present evidence suggest that we may actually have very high fecundity and a reproductive system that has evolved to be flexible, ruthlessly efficient and, most importantly, strategic. It would be instructive to know not only by what physiological mechanisms a just apportionment is made between the nutriment devoted to the gonads and that devoted to the rest of the parental organism, but also what circumstances in the life-history and e...

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Female reproductive development: A hazards model analysis

Cited by 11 publications

References 9 publications

The Proximate Determinants of Fertility in Populations Exposed to Chronic Hypoxia

The Proximate Determinants of Fertility in Populations Exposed to Chronic Hypoxia

Early sexual maturity among Pumé foragers of Venezuela: Fitness implications of teen motherhood

The ecology and evolutionary endocrinology of reproduction in the human female

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