Is the age of menopause determined in-utero?

Age at natural menopause and cognition

OBJECTIVES

To examine associations between age at natural menopause, childhood IQ and cognition at age 65 years. To determine if lower age at menopause partly mediates the effect of childhood IQ on cognition at age 65 years.

METHODS

Data were provided by a sub-cohort of women participating in a longitudinal study of brain ageing and health. Main variables were childhood IQ from a 1947 national survey of children born in 1936, age at natural menopause and five cognitive tests measured in 2000-2001.

RESULTS

Age at menopause was associated with childhood IQ (r = 0.221, P = 0.008) and with general cognitive function age 65 years (r = 0.246, P = 0.004). Multiple regression showed 44.4% of the reliable variance in cognitive ability age 65 years is contributed by IQ at an age of 11 years to which, years of education contributed an additional 3.9%. Structural equation modelling suggested that childhood IQ differences contribute 4.8% of the variance to age at natural menopause and that the relation between age at menopause and cognition at age 65 years was accounted for by childhood IQ.

CONCLUSION

Childhood IQ and age at menopause each have significant relations with general cognitive function age 65 years but the link between cognition age 65 years and age at menopause might be wholly explained by childhood IQ. The association between childhood IQ and age at menopause may be attributed to central neural mechanisms or, as argued here, to the effects of childhood IQ on adult general health.

High ponderal index at birth predicts high estradiol levels in adult women

Inter-individual variation in levels of sex hormones results from differences in genetic, developmental, and environmental factors. We tested a hypothesis that programming of the fetal neuroendocrine axis may predispose some women to produce higher levels of steroid hormones during their menstrual cycles as adults. One hundred forty-five regularly menstruating 24- to 36- year-old women collected daily saliva samples for one menstrual cycle. Data on women's birth weights and birth lengths were obtained from medical records. A positive relationship was observed between ponderal index at birth (an indicator of nutritional status, calculated as birth weight/(birth length)(3)) and levels of estradiol (E2) in menstrual cycles, after controlling for potential confounding factors. Mean E2 was 16.4 pmol/l in the low ponderal index tertile, 17.3 pmol/l in the moderate ponderal index tertile, and 19.6 pmol/l in the high ponderal index tertile (the high ponderal index group had significantly higher E2 than both low and moderate ponderal index groups, P=0.0001). This study shows a positive association between ponderal index recorded for women at birth and levels of E2 measured during their menstrual cycles as adults. This suggests that conditions during fetal life influence adult production of reproductive hormones and may contribute to inter-individual variation in reproductive function. In addition, because large size at birth is one of the factors linked with an increased risk of breast cancer, our findings provide a physiological link for the observed positive relationship between indicators of energetic conditions during fetal growth and breast cancer in women.

Intrauterine growth retardation and consequences for endocrine and cardiovascular diseases in adult life: does insulin-like growth factor-I play a role?

Low birth weight has been associated with an increased incidence of ischaemic heart disease (IHD) and type 2 diabetes. Endocrine regulation of fetal growth by growth hormone (GH) and insulin-like growth factor (IGF)-I is complex. Placental GH is detectable in maternal serum from the 8th to the 12th gestational week, and rises gradually during pregnancy where it replaces pituitary GH in the maternal circulation. The rise in placental GH may explain the pregnancy-induced rise in maternal serum IGF-I levels. In the fetal compartment, IGF-I levels increase significantly in normally growing fetuses from 18 to 40 weeks of gestation, but IGF-I levels are four to five times lower than those in the maternal circulation. Thus IGF-I levels in fetal as well as in maternal circulation are thought to regulate fetal growth. Circulating levels of IGF-I are thought to be genetically controlled and several IGF-I gene polymorphisms have been described. IGF-I gene polymorphisms are associated with birth weight in some studies but not in all. Likewise, IGF-I gene polymorphisms are associated with serum IGF-I in healthy adults in some studies, although some controversy exists. Serum IGF-I decreases with increasing age in healthy adults, and this decline could hypothetically be responsible for the increased risk of IHD with ageing. A recent nested case-control study found that adults without IHD, but with low circulating IGF-I levels and high IGF binding protein-3 levels, had a significantly increased risk of developing IHD during a 15-year follow-up period. In summary, the GH/IGF-I axis is involved in the regulation of fetal growth. Furthermore, it has been suggested that low IGF-I may increase the risk of IHD in otherwise healthy subjects. Hypothetically, intrauterine programming of the GH/IGF axis may influence postnatal growth, insulin resistance and consequently the risk of cardiovascular disease. Thus IGF-I may serve as a link between fetal growth and adult-onset disease.

Body mass index but not a polymorphism of the interleukin-1 receptor antagonist (IL-1 RA) gene is associated with age at natural menopause

BACKGROUND

A genetic component of the onset of menopause has been described and several candidate genes have been identified. We hypothesized that carriage of a polymorphism of the interleukin-1 receptor antagonist gene (IL-1 RA) is associated with an early age at menopause.

METHODS

In a prospective cohort study, 90 consecutive postmenopausal Caucasian women were genotyped by PCR for the presence of an 86-base pair tandem repeat polymorphism in intron 2 of IL-1 RA.

RESULTS

We found that 36/90 (40%) women were homozygous for the wild-type allele 1 and 49/90 (54%) women were heterozygous for any of the variant alleles (1/2 [n = 44], 1/3 [n = 3], 2/3 [n = 2]). Two women (2%) were homozygous carriers of the variant allele 2. The wild-type allele 1 was identified on 119 of 180 chromosomes for an allele frequency of 0.66. The polymorphic alleles 2 and 3 were present on 56 and 5 chromosomes, respectively (allele frequencies 0.31 and 0.03, respectively). No correlation between the IL-1 RA genotype and the age at menarche and menopause, the length of the reproductive period, and the number of deliveries and miscarriages was ascertained. As to allele frequencies, homozygous and heterozygous carriers of the variant allele 2 had a median age at menopause of 50 (range 40-48) years, compared to 49.5 (range 39-56) years for women with no allele 2 (p value 0.41). Women with at least one allele 2 had a median age at menarche of 13 (range 10-16) years, compared to 13 (range 10-17) years for women with no allele 2 (p value 0.1). Decreasing body mass index, but not smoking, was correlated with an increasing age at natural menopause (r = -0.23, p = 0.04).

CONCLUSIONS

Our preliminary data suggest that an 86-base pair tandem repeat polymorphism in intron 2 of IL-1 RA does not modulate the onset and cessation of menses in this cohort of Caucasian women.

Early ovarian ageing

Observations from reproductive biology, epidemiology, and clinical assisted reproduction support the hypothesis that the time interval between the onset of accelerated decline of the ovarian reserve and the menopause is more or less fixed. Thus, it is estimated that women who become menopausal by the age of 45 may have experienced an accelerated decline of their fertility before the age of 32. Up to 10% of women in the general population may fall into this category, which has been described as "early ovarian ageing". Because of the long latent phase and predictable natural history, this condition is suitable for screening. High-risk groups include, women with a family history of early menopause. IVF has provided a model for the development of ovarian reserve tests, some of which appear promising as potential screening tools for the detection of early ovarian ageing in asymptomatic women in the general population.

Month of birth predicted reproductive success and fitness in pre-modern Canadian women

Conditions experienced during early development affect human health and survival in adulthood, but whether such effects have consequences for fitness is not known. One surrogate for early conditions is month of birth, which is known to influence health and survival in many human populations. We show that in nineteenth century Canada, month of birth predicted a woman's fitness measured by the number of grandchildren produced, with the genetic contribution to the following generations by women born in different months differing by over seven grandchildren. This difference was mainly caused by differences in the reproductive rates of both mothers and their offspring, rather than differences in their survival. Women born in the best months of the year had longer reproductive lifespans, larger numbers of live births and raised more offspring to adulthood than those who were born in the worst months. Furthermore, the offspring of those women born in the best months also had greater reproductive rates, suggesting that month of birth also influenced a mother's ability to invest in her offspring. Our results suggest that early conditions may have important consequences for human lifetime reproductive performance within and between generations, and that timing of birth had large effects on fitness in this rural community.

Caloric restriction reduces age at menopause: the effect of the 1944–1945 Dutch famine

OBJECTIVE

To assess the effect of caloric restriction, as endured during the 1944-1945 Dutch famine, on the age at which natural menopause occurs and to identify specific vulnerable age periods in which caloric restriction has the largest effect.

DESIGN

This was a population-based cohort study conducted in Utrecht, the Netherlands. Between 1983 and 1986, 9,471 women aged 40 to 73 years at the time of interview were classified regarding their exposure to the famine. Age at natural menopause was obtained from all available data, retrospectively as well as prospectively. We estimated differences in mean age at natural menopause between famine exposure categories (not, moderately, and severely exposed), with adjustment for smoking, parity, socioeconomic status, body mass index, age at menarche, and year of birth.

RESULTS

Women experienced natural menopause on average 0.36 years earlier (95% CI: -0.60, -0.11) when severely exposed to the famine and 0.06 years earlier (95% CI: -0.22, 0.09) when moderately exposed compared with the unexposed women. This effect was particularly pronounced in those severely exposed from 2 to 6 years of age: -1.83 years (95% CI: -3.03, -0.63).

CONCLUSIONS

Our findings suggest that caloric restriction decreases age at natural menopause. Early childhood seems to be a particularly sensitive age period for this effect.

Early developmental conditions and reproductive success in humans: downstream effects of prenatal famine, birthweight, and timing of birth

Growth, survival, and breeding success of individuals in populations of wild mammals are influenced by the climatic and nutritional conditions that individuals experience during their early development. Recent findings have shown that early conditions also have consequences for subsequent survival and reproductive performance in humans. Environmental conditions which affect early development of individuals, such as the quality and quantity of nutrition received in utero and infancy, predict the onset of many chronic diseases in adulthood, affect longevity and may also influence a range of measures of reproductive performance in both food-limited and contemporary Western human populations. These associations are proposed to result from foetal programming, where a stimulus or insult during a critical period early in life may permanently affect body structure, physiology, and metabolism. Here I review studies showing how birthweight, season of birth, or exposure to prenatal starvation affect different aspects of an individual's subsequent reproductive success in humans and the growth, survival, and reproductive performance of the offspring produced. I show that early maternal and environmental conditions can have a large impact on human reproductive strategies and fitness that can span across generations.

Skewed X-chromosome inactivation is associated with trisomy in women ascertained on the basis of recurrent spontaneous abortion or chromosomally abnormal pregnancies

An increase in extremely skewed X-chromosome inactivation (XCI) (> or = 90%) among women who experienced recurrent spontaneous abortion (RSA) has been previously reported. To further delineate the etiology of this association, we have evaluated XCI status in 207 women who experience RSA. A significant excess of trisomic losses was observed among the women who had RSA with skewed XCI versus those without skewed XCI (P=.02). There was also a significant excess of boys among live births in this group (P=.04), which is contrary to expectations if the cause of skewed XCI was only that these women carried X-linked lethal mutations. To confirm the association between skewed XCI and the risk of trisomy, an independent group of 53 women, ascertained on the basis of a prenatal diagnosis of trisomy mosaicism, were investigated. Only cases for which the trisomy was shown to be of maternal meiotic origin were included. The results show a significantly higher level of extreme skewing (> or = 90%) in women whose pregnancies involved placental trisomy mosaicism (17%) than in either of two separate control populations (n=102 and 99) (P=.02 compared with total control subjects). An additional 11 cases were ascertained on the basis of one or more trisomic-pregnancy losses. When all women in the present study with a trisomic pregnancy (n=103) were considered together, skewed XCI was identified in 18%, as compared with 7% in all controls (n=201) (P=.005). This difference was more pronounced when a cutoff of extreme skewing of 95% was used (10% vs. 1.5% skewed; P=.002). Maternal age was not associated with skewing in either the patient or control populations and therefore cannot account for the association with trisomy. Previous studies have shown that a reduced ovarian reserve is associated with increased risk of trisomic pregnancies. We hypothesize that the association between skewed XCI and trisomic pregnancies is produced by a common mechanism that underlies both and that involves a reduction of the size of the follicular pool.

Lifetime socioeconomic position in relation to onset of perimenopause

STUDY OBJECTIVE

To assess the association between lifetime socioeconomic position and onset of perimenopause.

DESIGN

Prospective cohort study.

SETTING

Boston, Massachusetts.

PARTICIPANTS

603 premenopausal women aged 36-45 years at baseline who completed a cross sectional survey on childhood and adult socioeconomic position.

MAIN OUTCOME MEASURES

Time to perimenopause, defined as time in months from baseline interview to a woman's report of (1) an absolute change of at least seven days in menstrual cycle length from baseline or subjective report of menstrual irregularity; (2) a change in menstrual flow amount or duration; or (3) cessation of periods for at least three months, whichever came first.

MAIN RESULTS

Incidence of perimenopause was 1.75 times higher (95%CI 1.10 to 2.79) and median age at onset was 1.2 years younger (44.7 v 45.9 years) for women reporting childhood and adult economic distress compared with women reporting no lifetime economic distress. After adjustment for age, race/ethnicity, age at menarche, parity, oral contraceptive use, family history of early menopause, depression, smoking, and body mass index, the association weakened (incidence rate ratio (IRR)=1.59; 95%CI 0.97 to 2.61). Inverse associations were observed for most, but not all, measures of educational level. Measures of current household income were not associated with risk of perimenopause.

CONCLUSIONS

This study suggests that adverse socioeconomic conditions across the lifespan, when measured in terms of economic hardship and low educational attainment, may be associated with an increased rate of entry into perimenopause.

Early puberty in adopted children

Early puberty is frequently observed in adopted children. In various studies, early puberty has been associated with decreased final height. In Europe, studies were undertaken to treat early puberty in adopted children with GnRH agonist. This article reviews the current understanding of early puberty in adopted children, including prevalence, background and treatment options. Data from the European studies are briefly described. Besides auxological aspects, psychological items are addressed as well. Studies on the psychological effect of early puberty in adopted children are reported. Future issues include further study in the mechanism of early puberty in adopted children, evaluation of final height results of the growth studies and quality of life assessments in this specific group of children.

The perimenopause: definitions, demography, and physiology

The perimenopausal years should serve to remind patients and clinicians that this is a time for education. Certainly preventive health care education is important throughout life, but at the time of midlife, a review of the major health issues can be especially rewarding. The failure to respond appropriately (by either clinician or patient) easily leads to a loss of the patient from a practice, but equally, if not more importantly, is the probability that the loss of a patient from a practice means that another woman has lost her involvement in a preventive health care program. Contrary to popular opinion, the menopause is not a signal of impending decline, but rather a wonderful phenomenon that can signal the start of something positive, a good health program.

Early puberty in girls

Early puberty is not well defined in paediatric endocrinology. This chapter reviews the current insights on definitions, patient groups and treatment modalities in girls with early puberty. It is concluded that there is no clear evidence for a beneficial effect of gonadotrophin releasing hormone agonist (GnRHa) treatment in auxological terms. A clinical approach is presented, including both auxological and psychological items. Further research is needed to answer the question of whether early puberty should be treated with GnRHa.

[Smoking and ovarian fertility]

Smoking reduce the natural fertility and the delay to conceive increase with the number of cigarettes. In In Vitro Fertilization, the pregnancy rates per cycle are reduced with smokers compared with no smokers (OR: 0.66). The menopause arrive on average 2 years before with the smokers and the damages of ovarian reserve increase with smoking. The deleterious effects on ovary arrive, early in utero with regard to maternal smoking, and after the puberty, on the pre-ovulatory period where toxic, vascular and mutagen effects induce inhibition of ovocyte apoptosis, promoting ovocyte aneuploidy and subsequently miscarriage. The protection of ovarian fertility is one argument more to stop early smoking.

Second generation effects of maternal alcohol consumption during pregnancy in rats

1. Previous studies have shown that when female rats are administered alcohol during pregnancy there are adverse effects on their progeny, including decreased birth weight and delayed neuromotor development. Evidence from several sources suggests alcohol exposure may contribute to cytogenetic abnormalities, suggesting the possibility of cross generational effects from prenatal exposure. 2. On day 1 of gestation female rats were randomly allocated to the Alcohol group, which received a liquid diet containing 5% (v/v) ethanol solution until parturition, the Sucrose control group, which received an identical diet, except that sucrose had been isocalorically substituted for ethanol, or the Chow control, which received standard laboratory chow. 3. When the offspring of these rats reached adulthood they were mated with drug-free rats and the development of their offspring was monitored. 4. In comparison with female pups whose sires had been exposed to alcohol in utero, the weight of pups descended from fetally-exposed dams increased more slowly from day 1 to day 7. 5. At five days of age, significant differences favouring the two control groups were found in latency to right for pups descended from fetally-exposed dams. 6. These data suggest that the effects of prenatal exposure to alcohol are more pervasive than previously thought and affect female pups to a greater extent than males.

The menopause transition and the aging process: a population perspective

The menopause transition period, extending from active reproductive capacity with well-characterized hormone profiles through reproductive senescence, has been less well studied than any other period of the life span except extreme old age. Yet, for the gerontologist, this is an important period to understand for at least two reasons. First, during this period changes in the neuroendocrine system and ovary may provide a model for the study of other aging-related processes. Second, specific characteristics of this transitional period (including duration, intensity, and age at menopause) may be considered "aging", and influence short-term health and quality-of-life status, as well as life expectancy. In addition to discussing the menopause transition in terms of age and culture, we include some of the theories and conceptual models that can influence the nature and interpretation of information from this time period, and its ultimate impact on health and health practice.

Postnatal health and welfare of offspring conceived in vitro: a case for epidemiological studies

In vitro fertilization (IVF) has established itself as an important technique in human assisted reproduction and in livestock improvement. In both humans and livestock the possible long-term effects on health and welfare of offspring born after IVF and in vitro culture to the blastocyst stage are still largely unknown. Epidemiological studies in humans, using data collected for individuals born after normal (i.e. non-assisted) pregnancies, have provided evidence for associations between prenatal life events and adult-life disease. Due to the relatively short time that elapsed since the first IVF baby was born, comparable studies for IVF offspring are not yet possible. However, animal experiments and epidemiological studies with the available data from the livestock industry (mainly dairy cattle) may contribute to a better understanding of the risks involved.

Birth weight and age at menopause in Australian female twin pairs: exploration of the fetal origin hypothesis

In a twin sample where duration of gestation can be controlled, a specific example of the fetal origins hypothesis concerning association between low birth weight and early age at menopause is explored. The hypothesis is based on the physiologically plausible path from intrauterine growth retardation and reduced numbers of primary follicles to an earlier menopause. The sample comprised 323 Australian female twin pairs where both co-twins had reached menopause naturally and reported on their weight at birth. Regression analysis showed no linear association between the two variables (P = 0.371, r(2) = 0.0009). Intra-pair differences in age at menopause were investigated in the context of relative birth weight of co-twins. In 265 pairs an intra-pair birth weight difference was reported. In monozygotic (MZ) pairs (n = 168) this allowed for control of genetic effects as well as gestation duration. No significant differences dependent on birth weight relative to co-twin were found for age at natural menopause in either MZ or dizygotic (DZ) twin pairs, even in pairs whose birth weights differed markedly. There was some indication that twins with premature ovarian failure were heavier at birth than twins with normal or later menopausal age. We conclude that the hypothesis that lower birth weight is associated with earlier menopause is not supported by our data.

Maternal effects on the development of social rank and immunity trade-offs in male laboratory mice (Mus musculus)

Social status in randomly constituted groups of male CFLP mice was predictable from early suckling behaviour and rate of weight gain in natal litters. High-ranking males were those that had suckled on more anterior teats and gained weight more quickly. Rank was not predicted by any measures of sibling interaction or hormone (testosterone, corticosterone) concentration. Aggressiveness in eventual high-rankers was associated negatively with the proportion of males in the litter at birth and the amount of maternal attention received. Aggressive social relationships within natal litters did not predict polarized rank relationships in randomized groups. Nevertheless, while still in their natal litters, and in the absence of aggressive rank relationships, eventual rank categories showed the same difference in modulation of testosterone concentration in relation to current immunocompetence (low-rankers modulating, high-rankers not), as has repeatedly been found in randomized groups by earlier studies. The role of maternal condition in determining rank-related life-history development in male mice is discussed.