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PubMed1978

Mass isolation and fertility testing of temperature-sensitive mutants in Tetrahymena.

A set of 239 heat-sensitive (38 degrees) and 16 cold-sensitive (18 degrees) conditional mutants of Tetrahymena has been generated by combining techniques to manipulate large numbers of clones with a method for the selection of self-fertilized cells after mutagen treatment. A simple technique is presented for determining the fertility of individual clones; 179 of the clones in this set (71%) are fertile. The fertile conditional mutants have already been shown to have lesions in a number of diverse functions, including nucleic acid metabolism, mobility, cell cycle, and cortical pattern.

Animals↗
PubMed1999

Measuring aspects of women's life and work for the study of variations in health.

BACKGROUND: Studies of occupation and health commonly examine only men. This paper draws on reviews of inequalities in health carried out by the Office for National Statistics in London which in recent years have focused more on women. METHODS: Many sources of official statistics such as censuses, surveys, vital registration and health service records are used to explore different ways of measuring and monitoring economic activity, education, socio-economic, and family status and their impact on fertility and health among women. RESULTS: Taking a life cycle approach we first look at fertility and family formation, the time around childbirth, age 15-49, and finally 50+. Some relevant health issues are used to illustrate how we use available data to describe and monitor inequalities in health. CONCLUSIONS: In Britain, there is a wealth of information and linked data sources which enable us to analyze patterns and trends in fertility, morbidity, and mortality. Nevertheless, none of the traditional data sources or methods of analysis are suitable for all purposes nor for keeping up with changes in society. Sources of official statistics and ways of linking and analyzing need then to be continuously developed.

Female↗
PubMed1989

Blunted LH surge after HCG administration in cycles superovulated for in-vitro fertilization.

The preovulatory pattern of serum luteinizing hormone (LH) was investigated in cycles superovulated for in-vitro fertilization (IVF). The method used was immunoradiometric assay which shows no cross-reactivity with human chorionic gonadotrophin (HCG) at concentrations usually found after HCG administration. Of the 245 cycles stimulated by clomiphene citrate + human menopausal gonadotrophin, an endogenous LH surge was observed in 29.8% of the patients shortly prior to the HCG injection. In the post-HCG period, 49.4% of the cycles exhibited a blunted LH rise, whereas in the remaining 20.8% the LH level did not exceed twice the mean preovulatory value. According to the oestradiol-17 beta (E2) and progesterone concentrations, different hormonal patterns were found in patients with pre-HCG and post-HCG elevation of LH. However, the occurrence of a blunted LH surge following HCG administration cannot be attributed to different, HCG-induced secretory patterns of progesterone. There were no significant differences in clinical parameters, the pregnancy rate was slightly but not significantly higher (19.0%) in the post-HCG LH surge group than in the two other groups (13.7%). It is presumed that various factors may contribute to the suspension of preovulatory LH suppression. The possible beneficial influence of a post-HCG surge of LH requires further investigation.

Chorionic Gonadotropin↗
PubMedDate not supplied

The use of breastfeeding as a contraceptive.

Breastfeeding generally is considered an ineffective method of birth control. Yet, in non-Western cultures breastfeeding has been shown to be a beneficial method for spacing births. The physiological effect of breastfeeding on ovulation, breastfeeding patterns that delay the return of ovulatory activity, and the practice of fertility awareness during the postpartum period are reviewed. Guidelines are suggested for assessing, teaching, and referring women desiring to use breastfeeding as a contraceptive method.

Breast Feeding↗
PubMed2000

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

Choosing an appropriate contraceptive method, particularly one based on fertility awareness, depends in part upon the degree of a woman's cycling regularity. However, while the suppressive effect of lactation on ovarian function is well established, the potential influence of continued breastfeeding on menstrual patterns once post-partum cycling has resumed is largely unexamined. This longitudinal study in a population of non-contracepting Aymara women (n = 191 providing 665 non-truncated menstrual segments) identified conceptions and fetal loss via urine tests for hCG and classified segments accordingly to test the hypotheses that (1) cycles in lactating women are significantly different in length and regularity from those of non-lactating women, and (2) cycles in women living at high altitude are significantly different in length and regularity from those at lower altitudes. Analyses found that segments are significantly longer and regularity tends to be less common among lactating than non-lactating women; however, the rate of conception is twice as great among the former than the latter, and the distribution of conception outcomes does not differ between the two groups. Menstrual regularity is not the norm in this population, even among those who are not currently breastfeeding. High altitude per se does not appear to influence menstrual cycling as both regularity and segment length are comparable to other populations, hence women indigenous to high altitude are suitable candidates for a wide variety of contraceptive choices. In addition, these findings suggest that studies of fecundability limited to non-lactating women may be biased towards those of relatively lower fecundity.

Bolivia↗
PubMed1988

Control of fertility and fecundity of sheep by means of hormonal manipulation.

The results of four experiments are presented in summary form. The data are considered in relationship to the improvement of the fecundity and fertility of the Australian ewe breeding flock. In the first, three commonly used methods of oestrous synchronization were examined and showed differences that are attributed to the different patterns of hormonal changes associated with the methods demonstrated. The second experiment looked at the use of active immunization against testosterone and concluded that this method can improve fecundity but not fertility. The third experiment, a group of five trials, studied the use of progestagen sponges and PMSG in anoestrous ewes as a means of inducing normal fertility. The extensive data produced in this experiment allowed the relationships between ovulation rate and fertility and between fertility and prolificacy (fecundity) to be examined. Fertility appeared greatest when the mean flock ovulation rate was about 2.5. At this ovulation rate prolificacy was also improved and a high proportion of twins were produced. We concluded that high fertility and low prolificacy (i.e. of 1.00) are an unlikely combination. In the final experiment the effect of post-mating hormonal supplementation on fertility was examined and a number of earlier reports were confirmed by showing that fertility can be improved with supplementary progesterone between days 10 and 25 post-mating. The effect appears to be modified by hormonal and nutritional factors.

Animals↗
PubMed1984

Nutritional thriftiness and human reproduction: beyond the critical body composition hypothesis.

The 'critical body composition hypothesis' (CBCH) is frequently used to explain variations in the duration of postpartum amenorrhea. The hypothesis predicts that ovulation will not occur it fat reserves fall below a critical threshold. This paper attempts to analytically separate the CBCH from the broader concept of nutritional thriftiness on which it is based. A review of previous research on fat cell metabolism and ovulation finds no direct link between fatness and fecundity. Rather they are each regulated by the lactation and mother-infant interactions associated with breast feeding. As a system which delivers available fat into breast milk and prevents ovulation only during the time when the infant is dependent on the mother, the pathways outlined here represent a nutritionally thrifty method of fertility regulation, one which maximizes reproductive success while minimizing energy investment. The cultural patterning both of infant feeding behaviors and the wider range of maternal activities which affect breast feeding suggest specific testable hypotheses to explain interpopulation variations in fertility and infant nutritional status.

Adipose Tissue↗
PubMed1993

The spatial dynamics of U.S. fertility, 1970-1990.

"The fertility downturn in the U.S. since the baby boom has been accompanied by a growing divergence in regional fertility rates. This paper examines the spatial implications of recent fertility trends. Two interrelated questions are posed. First, how and why have the time trends in fertility varied spatially? Second, how have the regional patterns of fertility changed over time? These questions are investigated using a continuous spatio-temporal model of U.S. fertility built using the Dual Expansion Method. Results indicate that the pace of fertility decline has been the most rapid in the Northeast and the slowest in the West. Further, the traditional North-South distinctions in fertility rates are being replaced by East-West patterns. These changes tentatively suggest that regional ethnic composition is becoming an increasingly important factor in accounting for the spatial variation of U.S. fertility."

Americas↗
PubMed1999

Impaired fertility in HIV-1-infected pregnant women: a clinic-based survey in Abidjan, Côte d'Ivoire, 1997.

OBJECTIVE: Differences in fertility among HIV-1-positive and HIV-negative women tested in prenatal clinics were suspected by routine data collection in Abidjan, Côte d'Ivoire. This study was conducted on detailed fertility patterns among women at the same antenatal care centres, in order to assess these differences. METHOD: The survey was carried out on 1201 consecutive women who agreed to be tested for HIV. Data collected included a detailed account of pregnancies, the time interval between the last two pregnancies, and the health status at the time of the survey. Blood samples were tested for HIV and syphilis with informed consent. RESULTS: Despite an earlier exposure to pregnancy risk, HIV-1-infected women aged 25 years and above, had, on the average, fewer pregnancies than uninfected women. An analysis of the interval between the last two pregnancies among multigravidae showed that, all things being equal, being HIV-1 positive decreased the risk of being pregnant by 17% (Cox regression, hazard ratio = 0.83, 95% confidence interval (CI): 0.69-0.99). This shift in the occurrence of the last pregnancy was more profound among HIV-1-positive women already at the symptomatic or AIDS stage, than among asymptomatic women. CONCLUSION: These data confirm that women infected by HIV-1 would become pregnant less often than uninfected women, for an equal exposure to the risk of pregnancy. Therefore HIV-1-positive women could be under-represented at antenatal centres. Programmes involving such settings both for epidemiological surveillance and the reduction of mother-to-child transmission should take this observation into account.

Adult↗
PubMed2001

Polycystic ovarian syndrome: a follow-up study on fertility and menstrual pattern in 149 patients 15-25 years after ovarian wedge resection.

BACKGROUND: The aim of this study was to evaluate fertility and menstrual pattern in women with polycystic ovarian syndrome (PCOS) 15-25 years after ovarian wedge resection (OWR). METHODS AND RESULTS: The diagnosis was based on the combination of ovarian pathology and symptoms. The 149 patients, all primarily treated at a university teaching hospital, were studied three times by means of a questionnaire up to 25 years after surgery. Kaplan-Meier analysis showed a cumulative rate of spontaneous pregnancies of 76%, increasing to 88% when induced pregnancies were included. The cumulated live birth rate was 78%. A bootstrap simulation indicated that 69.5% would develop post-operative adhesions, which could impede pregnancy in 13.4%. In the majority of the patients a regular menstrual pattern was restored up to 25 years after OWR. CONCLUSION: The results of OWR in PCOS are favourable to most modern treatments. Laparoscopic electrocautery of the ovaries is the only method equally successful, and, by being less invasive, it has made OWR history in the treatment of PCOS.

Female↗
PubMed2001

Simple, directional cDNA cloning for in situ transcript hybridization screens.

Here, we describe a suppression PCR-based method for directional cloning of randomly primed cDNAs from small quantities of tissue. Synthesis of the first cDNA strand is conducted on oligonucleotide-coated magnetic beads. Synthesis of the second strand is accomplished using nonspecifically primed suppression PCR. This method is used to synthesize a cDNA library from zebrafish embryos at 6-9 h after fertilization. The sequencing of the clones and their use in an in situ hybridization screen to detect restricted patterns of gene transcription in zebrafish embryos showed that this method allows the rapid identification of genes that are important for development and genes that are expressed at levels undetectable by whole-mount in situ transcript hybridization. The random priming of cDNA alleviates the problems encountered in the identification of zebrafish genes from poly(dT)-primed cDNA clones caused by the long 3' UTRs frequently found in transcripts from this organism.

Animals↗
PubMed2002

Practice patterns among board-certified reproductive endocrinologists regarding high-order multiple gestations: a united states national survey.

OBJECTIVE: To assess current practice management, attitudes, and strategies of reproductive endocrinologists in the United States regarding high-order (at least three) multiple gestations. METHODS: Questionnaires were mailed to 768 board-certified reproductive endocrinologists of whom 722 were eligible for the study. The questionnaires addressed topics such as practitioner demographics, management strategies, and attitudes regarding high-order multiple gestations. RESULTS: The survey response rate was 52%. Most physicians performed 100-300 cycles of each ovulation induction with intrauterine insemination and in vitro fertilization in 1998 and 1999. The most commonly reported incidence of high-order multiple gestations resulting from each ovulation induction with intrauterine insemination and in vitro fertilization was 2-5% in 1998 and 1999. Strategies used to decrease the rate of high-order multiple gestations varied among practitioners. Informed consent regarding high-order multiple gestations was provided by 99.5% of practitioners. Information regarding selective reduction was provided by 98.3% of respondents. Over 90% of practitioners believed it is worthwhile to attempt to decrease the risk of high-order pregnancies at the risk of decreasing their group's overall pregnancy rates. CONCLUSION: Most reproductive endocrinologists reported concern over the rising risk of high-order multiple gestations resulting from therapies such as superovulation with intrauterine insemination or in vitro fertilization. However, the ways in which patients are counseled regarding such events, their sequelae, and methods to avoid them greatly differ among respondents. Given the inconsistent practice patterns, a multifaceted educational approach may provide an opportunity to reduce the incidence of high-order multiple gestations and their sequelae.

Counseling↗
PubMed2002

Utilization of a particle gun DNA introduction system for the analysis of cis-regulatory elements controlling the spatial expression pattern of the arylsulfatase gene (HpArs) in sea urchin embryos.

We applied a particle gun method to introduce DNA into fertilized sea urchin eggs for the analysis of cis-regulatory elements responsible for spatial gene expression during development. We introduced HpArs (sea urchin arylsulfatase gene) -GFP and HpArs-LacZfusion constructs into the fertilized eggs and obtained high expression levels of the fusion genes. Using this assay system, we demonstrated that a fragment of HpArs (-3,484 to +4,636) is sufficient for aboral ectoderm-specific expression, and that the region in the first intron from +406 to +1,993 contains the control elements responsible for the repression of the HpArs promoter activity in secondary mesenchyme cells.

Animals↗
PubMed1999

Contraceptive use dynamics of Asian women in Britain.

In-depth interviews were conducted with married Asian women from Indian, Pakistani and Bangladeshi backgrounds, to investigate patterns of contraceptive use and influences on contraceptive decision making. The results show two distinctively different contraceptive 'lifecycles'. Non-professional women typically have little knowledge about contraception until after their marriage or first birth. Their patterns of contraceptive behaviour show low levels of contraceptive use until after their first birth, when condom use is most prevalent. Non-professional women are influenced by their extended family, religion and cultural expectations on their fertility and family planning decisions. Professional women show an entirely different pattern of contraceptive behaviour. They are more likely to have knowledge about contraception before marriage, use some method of contraception throughout their childbearing years (typically the pill) and cite personal, practical or economic considerations in their fertility decisions rather than religious, cultural or extended family influences.

Adult↗
PubMed1984

The demographic transition.

Demographic transition is a set of changes in reproductive behavior that are experienced as a society is transformed from a traditional pre-industrial state to a highly developed, modernized structure. The transformation is the substitution of slow growth achieved with low fertility and mortality for slow growth maintained with relatively high fertility and mortality rates. Contrary to early descriptions of the transition, fertility in pre-modern societies was well below the maximum that might be attained. However, it was kept at moderate levels by customs (such as late marriage or prolonged breastfeeding) not related to the number of children already born. Fertility has been reduced during the demographic transition by the adoption of contraception as a deliberate means of avoiding additional births. An extensive study of the transition in Europe shows the absence of a simple link of fertility with education, proportion urban, infant mortality and other aspects of development. It also suggests the importance of such cultural factors as common customs associated with a common language, and the strength of religious traditions. Sufficient modernization nevertheless seems always to bring the transition to low fertility and mortality.

Birth Rate↗