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PubMed2004

The male red-sided garter snake (Thamnophis sirtalis parietalis): reproductive pattern and behavior.

Among the small group of species (e.g., some temperate zone turtles, snakes, and bats) that exhibit a dissociated reproductive pattern, the red-sided garter snake (Thamnophis sirtalis parietalis) is probably the most well studied. For these species, courtship and mating occur immediately upon emergence from winter dormancy; the gonads remain essentially inactive. Male red-sided garter snakes are a particularly informative animal model for examining the role of neuroendocrine factors associated with reproductive physiology and behavior because unlike species that exhibit an associated reproductive pattern, in which sex steroids initiate and control sexual behavior, reproductive behavior in the male garter snake appears to be independent of circulating sex hormone control. In fact, the only factor associated with the initiation of courtship behavior and mating in the male garter snake is an extended period of low temperature dormancy followed by exposure to warm temperatures. Yet the presence of sex steroid-concentrating neurons within the pathways regulating courtship and mating suggests that sex hormones may be involved in the activation of sexual behavior. Although circulating androgens are elevated upon emergence from hibernation, the initiation of courtship behavior and mating appears to be independent of direct androgen control. Thus steroid hormones may have indirect effects on mating behavior in animals that display "dissociated" reproductive behaviors.

Animal Husbandry↗
PubMed2003

Effects of oyster extract on the reproductive function of zinc-deficient mice: bioavailability of zinc contained in oyster extract.

Zinc is a vital nutrient in the normal reproductive function and embryonic development of mammals, and it is well known that oyster extract contains significant amounts of zinc. The effects of oyster extract on reproductive function, such as embryonic development, serum levels of zinc and sperm maturation were examined in zinc-deficient mice. Zinc deficiency in dams during pregnancy induced a decrease in the successful pregnancy rate, maternal weight gain, the number of live fetuses and fetal body weight. Zinc deficiency for 12 weeks in male mice induced a decrease in body weight, testis weight and sperm count in the epididymis. However, reproductive failure, embryonic defects and decreased sperm motility in zinc-deficient mice were improved by supplementation with oyster extract. Some nutrients contained in oyster extract, such as taurine and glycogen, may be related to the recovery of reproductive function. There were significantly lower serum concentrations of zinc in dams fed a zinc-deficient diet. However, the serum zinc concentration was normal in the oyster extract-supplemented group. No difference in the concentration of serum zinc was observed between the oyster extract- and zinc carbonate-supplemented groups. From these findings, it is suggested that oyster extract is a useful supplement that can prevent reproductive defects from zinc deficiency, and the bioavailability of zinc may be identical to zinc carbonate.

Animals↗
PubMed2003

Human reproductive cloning, embryo stem cells and germline gene intervention: an Israeli perspective.

The perspectives of applying the cloning technology to human reproduction have generated much controversy. Israel was one of the first countries to adopt (in 1998) a Law that prohibits reproductive cloning. This is a moratorium for 5 years during which neither cloning of an entire human being nor genetic changes affecting human reproductive cells will be allowed. An aim of the Law is to allow the examination of the moral, legal, and social aspects of these technologies and their implications for human dignity. With the intention of not being an obstacle to the advancement of medical genetics, the Law provides for a yearly report to the Israel Health Minister on the state of scientific knowledge in these technologies. This article reflects the 2002-3 report, relating to scientific issues and bioethical opinions in Israel and in the world on human reproductive cloning, embryonic stem cell research and germline gene manipulation. In the Jewish tradition, the primary importance of saving lives and helping suffering patients can take precedence over the fears generated by modern genetic and reproductive research. Provided that new technologies are applied for medical indications and respecting human rights and human dignity, it is legitimate to explore their beneficial potential.

Bioethics↗
PubMed2004

Assisted reproductive technology surveillance--United States, 2001.

PROBLEM/CONDITION: In 1996, CDC initiated data collection regarding assisted reproductive technology (ART) procedures performed in the United States to determine medical center-specific pregnancy success rates, as mandated by the Fertility Clinic Success Rate and Certification Act (FCSRCA) (Public Law 102-493, October 24, 1992). ART includes fertility treatments in which both eggs and sperm are handled in the laboratory (i.e., in vitro fertilization and related procedures). Patients who undergo ART treatments are more likely to deliver multiple-birth infants than women who conceive naturally. Multiple births are associated with increased risk for mothers and infants (e.g., pregnancy complications, premature delivery, low-birthweight infants, and long-term disability among infants). REPORTING PERIOD: 2001. DESCRIPTION OF SYSTEM: CDC contracts with a professional society, the Society for Assisted Reproductive Technology (SART), to obtain data from fertility medical centers located in the United States. Since 1997, CDC has compiled data related to ART procedures. The Assisted Reproductive Technology Surveillance System was initiated by CDC in collaboration with the American Society for Reproductive Medicine, the Society for Assisted Reproductive Technology, and RESOLVE: The National Infertility Association. RESULTS: In 2001, a total of 29,344 live-birth deliveries and 40,687 infants resulting from 107,587 ART procedures were reported from 384 medical centers in the United States and U.S. territories. Nationally, 80,864 (75%) of ART treatments used freshly fertilized embryos from the patient's eggs; 14,705 (14%) used thawed embryos from the patient's eggs; 8,592 (8%) used freshly fertilized embryos from donor eggs; and 3,426 (3%) used thawed embryos from donor eggs. Overall, 40% of ART procedures that progressed to the transfer stage resulted in a pregnancy; 33% resulted in a live-birth delivery (delivery of > or =1 infant); and 21% resulted in a singleton live birth. The highest live-birth rates were observed among ART procedures using freshly fertilized embryos from donor eggs (47%). The greatest numbers of ART procedures were performed among residents of California (13,124), New York (12,379), Massachusetts (8,151), Illinois (7,933), and New Jersey (6,011). These five states also reported the highest number of live-birth deliveries and infants born as a result of ART. The ratio of number of ART procedures per million population ranged from 74 in Idaho to 1,273 in Massachusetts, with a national average of 371 ART procedures started per million persons. Among ART treatments in which freshly fertilized embryos from the patient's eggs were used, substantial variation in live birth rates by patient (e.g., women aged < or =40 years) and treatment characteristics (e.g., ovulatory dysfunction, endometriosis, or unexplained infertility) was observed. The risk for a multiple-birth delivery was highest for women who underwent ART transfer procedures using freshly fertilized embryos from either donor eggs (42%) or from their own eggs (36%). Among ART transfer procedures in which the patient's own eggs were used, an inverse relation existed between multiple-birth risk and patient age. Number of embryos transferred and embryo availability (an indicator of embryo quality) were also strong predictors of multiple-birth risk. Of the 40,687 infants born, 46% were twins, and 8% were triplet and higher order multiples. The total multiple-infant birth rate was 53%. Approximately 1% of U.S. infants born in 2001 were conceived through ART. Those infants accounted for 16% of multiple births nationally. INTERPRETATION: Whether an ART procedure resulted in a pregnancy and live-birth delivery varied according to different patient and treatment factors. ART poses a major risk for multiple births. This risk varied according to the patient's age, the type of ART procedure performed, the number of embryos transferred, and embryo availability (an indicator of embryo quality). PUBLIC HEALTH ACTION: ART-related multiple births represent a sizable proportion of all multiple births nationally and in selected states. Efforts should be made to limit the number of embryos transferred for patients undergoing ART.

Adult↗
PubMed2004

[The roles of arabinogalactan-proteins in sexual reproduction of angiosperms].

Arabinogalactan-proteins (AGPs) are a class of proteoglycans distributed mainly in the cell surfaces and extracellular matrix of most plants. Their numerous expressions have been detected in many male reproductive organs (pollen, pollen tube and sperm), female reproductive organs (stigma, style and ovary) and embryos (zygotic and somatic embryos) in many plants. Numerous investigations have demonstrated that AGPs are involved in the process of sexual reproduction of angiosperms and play multiple roles, e.g., providing surface adhesion, nutrients and directional cues or signals for pollen tubes. They may also participate in gametal recognition and embryo development and differentiation. But the mechanisms underlying these roles of AGPs are still unclear. Knowledge of AGPs in the structural components, characteristics, expression in reproductive tissues during the process of reproduction are summarized and the mechanisms underlying their functioning are discussed.

Magnoliopsida↗
PubMed2005

Adolescent reproductive health and gender role attitudes in Oman.

OBJECTIVE: The aim of the study was to investigate the attitudes of Omani adolescents towards the different gender roles and women empowerment with regard to taking household decisions, and to study how they influenced the adolescents' knowledge and attitudes towards some reproductive health issues in a national representative secondary schools-based sample of 1670 boys and 1675 girls. METHODS: In 2001, through a self administrated questionnaire the adolescents answered 2 indices; adolescents Attitudes Toward Gender Roles (ATGR) and adolescents Attitudes Toward Women Empowerment (ATWE) in addition to answering questions on demographic data, environmental factors, and questions assessing their knowledge and attitudes towards reproductive health issues. RESULTS: High scores of ATGR or ATWE were found to significantly predict sound adolescents' reproductive health knowledge or positive attitudes in almost all the logistic regression models. CONCLUSION: The study highlighted the scope of interventions to be initiated for adolescents reproductive health. Changes in attitudes towards gender role have to accompany our endeavors to set up the stage for our future generation's reproductive health.

Adolescent↗
PubMed2005

Reproductive issues for women with spina bifida.

BACKGROUND/OBJECTIVES: Few studies have adequately examined the unique issues of women with spina bifida as they enter their reproductive years. Most studies are anecdotal, retrospective case studies that contribute little to our understanding of the physiological effects of the disability on the reproductive system and, conversely, the effects of the reproductive endocrine changes on the woman's disability. The purpose of this article was to review previously published reports on the reproductive issues facing female adolescents and women and to ascertain the current knowledge so that future research needs can be established. METHODS: Multiple MEDLINE searches were performed for publications from 1957 through the present pertaining to females/women with spina bifida and/or disabilities. Papers were then chosen if information was provided on menarche, menstruation and sexual maturation, gynecologic issues, sexual function, birth control, pregnancy outcomes, and menopause. These were then reviewed and classified according to the level of evidence (as defined by Ball et al). RESULTS: More than 150 titles and abstracts were reviewed for inclusion. Of these, 75 papers met the guidelines for the subject content. Studies were stratified by level of evidence and included 1 study at level 3, 71 studies at level 4, and 3 studies at level 5. CONCLUSION: Little research has examined the reproductive issues of women with spina bifida and women with other neurologic disabilities. Future controlled prospective research studies are needed to examine issues related to puberty and sexual and gynecologic issues throughout the life span and pregnancy in these populations.

Adolescent↗
PubMed2005

[Effects of bisphenol A on the placental function and reproduction in rats].

OBJECTIVES: The aim of this study was to investigate the effects of bisphenol A (BPA), an estrogen-like environmental endocrine disrupter, on the placental function and reproduction in rats. The mRNA levels of the placental prolactin-growth hormone(PRL-GH) gene family, placental trophoblast cell frequency and reproductive data were analyzed. METHODS: The pregnancies of F344 Fisher rats (160 g +/-20 g) were detected by the presence of the copulatory plug or sperm in the vaginal smear, which marked Day 0 of pregnancy. Pregnant rats were divided into three groups. The control group was intraperitoneally injected with a sesame oil vehicle. The two remaining groups were injected with 50 or 500 mg/kg B.W/day of BPA, resuspended in sesame oil, on either days 7 to 11 or 16 to 20 of pregnancy, with the rats sacrificed on either day 11 or 20, respectively. The mRNA levels of PRL-GH and Pit-1a and b isotype genes were analyzed by Northern blot hybridization and reverse transcription-polymerase chain reaction. The hormone concentrations were analyzed by radioimmunoassay, and the frequency of the placental trophoblast cells observed by a histochemical study. Reproductive data, such as the placental weight and litter size, were surveyed on day 20. The fetal weight was surveyed for 4 weeks after birth. A statistical analysis was carried out using the SAS program (version 8.1). RESULTS: The mRNA levels of the PRL-GH gene family, such as placental lactogen I, Iv and II, prolactin like protein A, C and Cv, and decidual prolactin-related protein were significantly reduced due to BPA exposure. The mRNA levels of the Pit-1a and b isotype genes, which induce the expression of the PRL-GH gene family in the rat placenta, were also reduced due to BPA exposure. The PL-Iv and PL-II concentrations were reduced in the BPA exposed group. During the middle to last stage of pregnancy (Days 11-20), a high dose of BPA exposure reduced the frequency of spongiotrophoblast cells, which are responsible for the secretion of the PRL-GH hormones. Reproductive data, such as the placental and fetal weights and the litter size, were reduced, but that of the pregnancy period was extended in the BPA exposed compared to the control group. CONCLUSIONS: BPA disrupts the placental functions in rats, which leads to reproductive disorders.

Animals↗
PubMed2006

Lower group productivity under kin-selected reproductive altruism.

Hamilton's rule provides the foundation for understanding the genetic evolution of social behavior, showing that altruism is favored by increased relatedness and increased productivity of altruists. But how likely is it that a new altruistic mutation will satisfy Hamilton's rule by increasing the reproductive efficiency of the group? Altruism per se does not improve efficiency, and hence we would not expect a typical altruistic mutation to increase the mean productivity of the population. We examined the conditions under which a mutation causing reproductive altruism can spread when it does not increase productivity. We considered a population divided into temporary groups of genetically similar individuals (typically family groups). We show that the spread of altruism requires a pleiotropic link between altruism and enhanced productivity in diploid organisms, but not in haplodiploid organisms such as Hymenoptera. This result provides a novel biological understanding of the barrier to the spread of reproductive altruism in diploids. In haplodiploid organisms, altruism within families that lowers productivity may spread, provided daughters sacrifice their own reproduction to raise full-sisters. We verified our results using three single-locus genetic models that explore a range of the possible reproductive costs of helping. The advantage of female-to-female altruism in haplodiploids is a well-known prediction of Hamilton's rule, but its importance in relaxing the linkage between altruism and efficiency has not been explored. We discuss the possible role of such unproductive altruism in the origins of sociality. We also note that each model predicts a large region of parameter space were polymorphism between altruism and selfishness is maintained, a pattern independent of dominance.

Altruism↗
PubMed2005

NTP-CERHR monograph on the potential human reproductive and developmental effects of methylphenidate.

The National Toxicology Program (NTP) Center for the Evaluation of Risks to Human Reproduction (CERHR) conducted an evaluation of the potential for methylphenidate to cause adverse effects on reproduction and development in humans. Methylphenidate was selected for evaluation because of 1) widespread usage in children, 2) availability of developmental studies in children and experimental animals, and 3) public concern about the effect of this stimulant on child development. Methylphenidate is a central nervous system stimulant approved by the U.S. Food and Drug Administration for the treatment of attention deficit hyperactivity disorder (ADHD) in persons 6 years of age and older and for narcolepsy. The results of this evaluation on methylphenidate are published in an NTP-CERHR monograph which includes: 1) the NTP Brief, 2) the Expert Panel Report on the Reproductive and Developmental Toxicity of Methylphenidate, and 3) public comments received on the Expert Panel Report. As stated in the NTP Brief, the NTP reached the following conclusions regarding the possible effects of exposure to methylphenidate on human development and reproduction. First, there is negligible concern for methylphenidate-induced tics and movement disorders. This conclusion is based on studies showing that children treated with therapeutic doses of methylphenidate have no evidence of movement disorders or tics due to the medication. Second, there is minimal concern for methylphenidate-induced growth restriction. This conclusion is based on growth restriction being observed in animal studies only at high doses of methylphenidate using a non-therapeutic route of exposure. The effect on growth was reversible. Finally, there are insufficient data to draw conclusions on 1) an association between methylphenidate therapy in pregnant women and pregnancy loss and 2) possible reproductive effects of methylphenidate in humans. NTP-CERHR monographs are transmitted to federal and state agencies, interested parties, and the public and are available in electronic PDF format on the CERHR web site http://cerhr.niehs.nih.gov/ and in printed text or CD-ROM from the CERHR.

Animals↗
PubMed1991

Modern approaches to the treatment of human infertility through assisted reproduction.

Medical statistics from the United States show approximately 15 percent of all couples of reproductive age are unable to conceive naturally. In recent years, the numbers of couples with reproductive problems has increased, principally due to changes in life style and delayed childbearing. Only 13 years after the birth of the first "test tube baby", advances in the field of human reproduction have created a wide range of alternatives to help infertile couples conceive a healthy infant. Together, these techniques are called Assisted Reproductive Technology (ART) and include: in vitro fertilization (IVF), intratubal transfer of gametes (GIFT), intratubal transfer of zygotes (ZIFT), tubal transfer of preimplantation embryos (TET), gamete or embryo donation, cryopreservtion, and micromanipulation. The application of these techniques is presented here. While much remains to be learned, the ability to fertilize ova in vitro and sustain early embryonic life outside the body is now a reality. Contrary to the idea that these techniques create life in vitro, they simply remove barriers caused by different forms of infertility which impede the creation of life. More than 30,000 infants have now been produced world-wide through ART. In the future, new developments in the field of assisted reproduction promise to bring new hope to the growing numbers of infertile couples around the world.

Female↗
PubMedDate not supplied

Reproductive health in Romania: reversing the Ceausescu legacy.

As a result of the restrictive reproductive health policies enforced under the 25-year Ceausescu dictatorship, Romania ended the 1980s with the highest recorded maternal mortality of any country in Europe--159 deaths per 100,000 live births in 1989. An estimated 87 percent of these maternal deaths were caused by illegal and unsafe abortion. Under the Ceausescu regime, all contraceptive methods were forbidden and induced abortion was available only for women who met extremely narrow criteria. Immediately after the December 1989 revolution that overthrew Ceausescu, the new government removed restrictions on contraceptive use and legalized abortion. This legislative change has had beneficial effects on women's health, seen in the drop in maternal mortality in 1990 to 83 deaths per 100,000 live births--almost half the ratio in 1989. In addition, changes instituted since the revolution have led to the improved availability of reproductive health services and to the creation of new educational and training opportunities related to reproductive health services and to the creation of new educational and training opportunities related to reproductive health. The newly created contraceptive and abortion services have presented health system managers and policymakers with many challenges as they work to expand the availability of high-quality, comprehensive reproductive health care in a setting of economic hardship, political unrest, insufficient infrastructure, and outdated medical knowledge and practice.

Abortion, Legal↗
PubMed1978

Small animal reproductive problems.

Reproductive problems in the dog and cat are an important segment of the total case load in many veterinary practices. The interest in pet population control, estrus control, artificial insemination and planned pregnancies of pets as well as the advanced knowledge and technology in immunology, microbiology, pathology, physiology and related sciences are expanding the knowledge concerning pet reproduction. The use of radioimmunoassays (RIA) to detect minute amounts of hormones in the serum or plasma of animals has given the physiologist a precise biological measuring stick. As hormone testing laboratories become available, the RIA will become a valuable aide to the veterinary clinician, clients and their pets in diagnosing and possibly preventing or treating reproductive disorders. Knowledge of the normal canine and feline reproductive physiology, pathogenesis of reproductive disorders and a thorough history, genital tract examination, collection and examination of specimens for diagnosis and realistic treatments are all fundamental to a successful management of these disorders.

Animals↗
PubMed1985

Reproductive decision-making in the Upper Ramu District, Papua New Guinea: cognitive aspects of adaptive problem-solving.

This paper identifies specific interrelationships between political-economic, ecological, health and cultural parameters that shape reproductive choice in rural lowland families of the Usino region, Upper Ramu District, Madang Province, Papua New Guinea. Additionally, it compares their reproductive choices and strategies with those of upland groups in the same district. Lowland and upland cultural groups occupy distinct technological niches and follow distinct adaptive reproductive strategies consistent with their different perceptions of the value of children. In both cases, reproductive decisions are largely outcomes of economically rational cost-benefit analyses founded on divergent definitions of ecological, political, economic and technological conditions. This paper examines how reproductive decision-making reflects and is structured by Usino perceptions of the value of children, relative economic opportunity and health status; it elucidates the social levels at which these decisions are made and the adaptive rationality of those decisions; and it suggests both blind and intentional mechanisms of cultural selection.

Adolescent↗
PubMed1985

Nutrition and reproduction.

Adequate nutrition is essential for normal reproductive function in man. Menarche occurs at a critical level of 'fatness' and it appears that the hypothalamic events leading to pubertal development and the achievement of reproductive competence may be triggered by metabolic/endocrinological changes due to an increase in fat. The attainment and maintenance of ovulatory cycles demands a minimum degree of body fat (about 22%). Undernutrition results in weight loss and a reduction in fat tissue. This alteration in body composition in turn precipitates the hypothalamic changes that cause impaired gonadotrophin secretion, inappropriate ovarian stimulation and menstrual abnormalities--usually primary or secondary amenorrhoea. Refeeding with restoration of fat tissue will usually result in recovery of reproductive function. There are many causes of undernutrition and the main ones have been discussed. In developed countries the dietary restriction is usually self-imposed--either by rigid control of intake or by the high energy demands of intensive exercise. In contrast to this 'starvation amidst affluence', in developing countries malnutrition is usually the result of inadequate food supplies and poverty. While infertility is often the consequence of undernutrition, many women with suboptimal nutritional states do succeed in becoming pregnant. Malnutrition prejudices pregnancy outcome and results in increased maternal and fetal morbidity and mortality as well as long-term developmental sequelae in the infant. Dietary supplementation is helpful but cannot always overcome the insult caused by the periconceptional undernutrition. The cessation of reproductive function in the undernourished woman represents an adaptive phenomenon, since pregnancy would be prejudicial both to her and the fetus. In view of this, treatment should always aim at refeeding and not at induction of ovulation. Malnourished communities require dietary support and they present the problem of provision of adequate resources. So-called ethnic and culture differences in pubertal development and reproductive performances are in fact often the result of discrepancies in resources and nutrition. Given equal nutritional opportunities these variations may well disappear within a few decades.

Amenorrhea↗
PubMed1977

[Planned control of reproduction processes in industrialized cattle production].

Reference is made to the authors' own experience and to evaluated literature in an account of possibilities which so far have been explored for planned control of reproduction processes in industrialised cattle production. Synchronisation of oestrus in heifer has been found to be suitable for reproduction control even under conditions of industrialised production. The method has been in use on several farms. Synchronisation of oestrus in cow is an approach which still is in the process of translation into practice. Obtainable advantages, like those in the context of heifer, will include better job conditions. Systematic puerperal monitoring, too, will yield positive effects in controlling post-partum readiness of cow for reproduction. Results so far achieved include progress towards the introduction of a complex reproduction technology in cattle production. Before such complete system of reproduction control can be used, further studies are required into some fundamental aspects of the problem, including calving control, pregnancy examination, and gravidity hagiene.

Animals↗
PubMed1983

The mechanisms of action of reproductive toxins.

A general discussion of the mechanisms of action of reproductive toxins is presented. Reproductive toxicants may produce their adverse effects by one of several mechanisms. Some xenobiotics may act directly, either by virtue of chemical reactivity (eg, oocyte destruction by alkylating agents) or by structural similarity to endogenous molecules (eg, hormone antagonists). Other xenobiotics interrupt reproductive processes indirectly either by metabolic processing to a direct-acting toxicant (eg, prohormone or metabolic activation to reactive intermediate) or by altering endocrine homeostasis (eg, increased steroid clearance). Selected examples of compounds demonstrating reproductive toxicity by one or more of these mechanisms are tabulated and an extensive bibliography of reproductive toxins is attached.

Alkylating Agents↗
PubMed1980

Reproductive behaviour of wild chimpanzees in the Gombe National Park, Tanzania.

(1) The reproductive behaviour of chimpanzees in the Gombe National Park, Tanzania, was studied for 16 months and additional information came from 19 years of demographic data collected by Dr Jane Goodall and members of the Gombe Stream Research Centre. (2) The mating system of the Gombe chimpanzees comprises 3 mating patterns: (a) opportunistic, non-competitive mating, when an oestrous female may be mated by all the males in the group; (b) possessiveness, when a male forms a special short-term relationship with an oestrous female and may prevent lower ranking males from copulating with her; and (c) consortships, when a male and a female leave the group and remain alone, actively avoiding other chimpanzees. While males took the initiative in possessive behaviour and consortships, females had to co-operate for a successful relationship to develop. (3) Data from 14 conceptions indicated that the majority of females (9) became pregnant while participating in the restrictive mating patterns, possessiveness and consorting. Adult males showed differential frequencies of involvement in the restrictive mating patterns. The following male characteristics showed significant, positive correlations with participation in the restrictive patterns: (a) the amount of time spent in the same group as oestrous females, (b) the proportion of that time spent grooming oestrous females, and (c) the frequency with which males shared food with females. Dominance ranks of the adult males showed no consistent correlation with involvement in the restrictive patterns, but it was clear that the most dominant male did gain an advantage. He was the only male able to monopolize oestrous females by showing possessiveness. (4) Developmental and demographic data from observations for 19 years show that female chimpanzees have a very limited reproductive potential. Females reached menarche at about 11 years of age but this was followed by a period of adolescent sterility of median length 26 months. Each birth, if the infant survived, was followed by a long period of lactational amenorrhoea of median duration 42 months. The mean inter-birth interval of the Gombe chimpanzees was 5 years 8 months. Thus, the theoretical lifetime reproductive potential of females is 5-6 offspring who survive to weaning. Data on achieved reproductive success showed that females had a median of 3 births in their lifetime, with only 2 offspring surviving to reproductive age.

Animals↗