Menstrual patterns and fecundity among non-lactating and lactating cycling women in rural highland Bolivia: implications for contraceptive choice

Vitzthum, Virginia J.; Spielvogel, Hilde; Caceres, Esperanza; Gaines, Julia B.

doi:10.1016/s0010-7824(00)00164-5

Cited by 22 publications

(19 citation statements)

References 11 publications

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“…Ovarian cycle length in rural Aymara women averaged 29.1 days, which falls within the observed range for sea level [ 13 ]. The proportion of ovulatory cycles, as assessed by progesterone levels, was comparable in a sample of Chicago women and economically advantaged women in La Paz, Bolivia (91 % and 88 % respectively); however, it was far lower (45 %) in the poorer women of La Paz [ 14 ].…”

Section: Fertilitysupporting

confidence: 61%

Reproduction and Growth

Niermeyer

2013

High Altitude

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Reproduction and development during infancy and childhood present critical, vulnerable periods in the individual lifecycle and the health of a population. For humans living permanently at high altitude, the environment they inhabit adds risks for maternal and child health and survival. In addition to hypoxia, many high-altitude regions impose other constraints on the circumstances necessary for optimal fetal development and infant/child survival. These include impoverished living conditions, social inequalities, physically demanding livelihoods, nutritional defi ciencies, and infectious diseases. Such determinants infl uence fertility, fetal loss and growth, neonatal survival, and child development. Populations resident at high altitude for millennia, for example the Tibetans in the Himalaya and the Aymara and Quechua of South America, attest to possibility of not only surviving but also thriving, Hypoxia, as well as other environmental and social factors, shapes reproduction and fetal/infant growth at high altitude. Although fertility and early fetal loss differ little from patterns observed at lower altitude, placental development does differ and the medical complications of pre-eclampsia and post-partum hemorrhage pose greater risks at altitude. Reduction in birth weight with increasing altitude of gestation occurs across high-altitude regions, resulting in an increased proportion of lowbirth-weight infants (<2,500 g). However, the magnitude of reduction in fetal growth varies among population groups, depending on maternal ventilation, plasma volume expansion, blood fl ow to the uteroplacental circulation, and nutrient transport. Neonatal, infant, and child mortality are increased at high altitude. Respiratory problems account for the majority of neonatal and infant deaths. Exposure to hypoxia during the fetal and neonatal periods may have consequences that extend into adult life and span generations.

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Section: Fertilitysupporting

confidence: 61%

Reproduction and Growth

Niermeyer

2013

High Altitude

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“…For a sample of 612 cycles observed in 191 rural Aymara women, cycle length averaged 29.1 days (Vitzthum et al, 2000b). Compared to all other populations for which data are available in the literature, this Aymara sample falls neither particularly low nor high in the range of observed lengths, suggesting that if hypoxia does affect ovarian cycle duration the effect is insignificant.…”

Section: Length Of Ovarian Cyclesmentioning

confidence: 70%

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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“…6, 7, S1), the extent of cycle variability remains underappreciated. ''Natural family planning'' (aka ''fertility awareness'') methods are still widely promoted even though they require an uncommon level of cycle regularity (Burkhart et al, 1999;Vitzthum et al, 2000b), and many behavioral studies unjustifiably assume a 28-day cycle having an idealized hormonal profile (Shirtcliff et al, 2001).…”

Section: Segment (Cycle) Lengthmentioning

confidence: 99%

“…For example, of 303 Guatemalan women who self-identified as having regular cycles every 26-32 days, more than half were then observed to have 1 of 3 consecutive cycles fall outside this range (Burkhart et al, 1999). Bolivian, Indian, U.S. and European women all had similarly high levels of variability (Gunn et al, 1937;Chiazze et al, 1968;Mü n-ster et al, 1992;Belsey and Pinol, 1997;Vitzthum et al, 2000b;Creinin et al, 2004;Williams, 2006). About half or more of the woman in each study sample (Supporting Information Table S4) had a range in cycle length of 6 days and about a quarter had a range [2 weeks, even if only a few cycles were recorded by each woman.…”

Section: Segment (Cycle) Lengthmentioning

confidence: 99%

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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Menstrual patterns and fecundity among non-lactating and lactating cycling women in rural highland Bolivia: implications for contraceptive choice

Cited by 22 publications

References 11 publications

Reproduction and Growth

Reproduction and Growth

The Proximate Determinants of Fertility in Populations Exposed to Chronic Hypoxia

The ecology and evolutionary endocrinology of reproduction in the human female

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