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Results for “Fertile Period”

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PubMed1984

Coitus-induced ovulation and its implications for estimates of some reproductive parameters.

It is estimated here that, at the time of conception, the mean coital rate of young women who subsequently bear DZ twins is about 6% higher than that of the general population of young married women. This differential seems too small to account wholly for the greater promptness in conceiving DZ twins. Accordingly, it is suggested that coital rate is associated with DZ twinning in two ways. The major link seems to be indirect and mediated by erotic response which causes an increase in gonadotrophin levels and thus in double ovulation. In a minority of cases, frequent coitus may give rise to DZ twins via superfecundation, but it seems that, in human beings, the corpus luteum of one ovum will usually inhibit fertilization of any further ova after a short interval. The evidence presented here, though indirect, seems to suggest that, under particularly erotic conditions, double ovulation is sometimes induced. It seems reasonable to infer that coitus also occasionally provokes or accelerates single ovulations, thus impugning some rhythm methods of contraception. But there seems no very good evidence that rape induces ovulation. Some notes are added on the implications of induced ovulation for estimates of fecundability and of the length of the fertile period.

Adult↗

PubMed1999

Fertility estimation from open birth-interval data.

Censuses and surveys frequently collect information on period fertility through questions on the timing of last births. The standard approach to estimating fertility with open-interval data uses the proportion of women giving birth in the year before the interview. I propose a more efficient, maximum likelihood method for estimating fertility from open-interval data. I illustrate a mathematical derivation of the new method, perform sensitivity analyses, and conduct empirical tests with Brazilian census data. The new estimators have small biases and lower variance than standard estimators for open-interval data. Consequently, the new method is more likely to generate accurate results from small or moderately sized samples.

Adolescent↗

PubMed1995

Appendix interposition in the treatment of severe posterior urethral injuries.

The aim of this study was to investigate the applicability of the Mitrofanoff principle in the treatment of severe posterior urethral injuries and determine the feasibility of this technique with its early and late postoperative results. A total of 27 New Zealand rabbits (12 male and 15 female) was used (mean weight 2,272 +/- 343 gm.). Using general anesthesia the proximal part of the posterior urethra was transected completely and a 1 cm. segment was excised. A 2 cm. segment of appendix with its intact vascular pedicle was meticulously mobilized and anastomosed to the proximal and distal site of the urethra. Excretory urograms, voiding cystourethrograms, urodynamic investigation and histopathological examination were performed postoperatively. The fertility of the male rabbits was examined in the late postoperative period as well. These results were compared with those of a control group. There was no problem concerning voiding patterns in the pedicled appendiceal flap group. Excretory urograms revealed a properly functioning urinary system. Voiding cystourethrograms showed a normal bladder capacity and voiding pattern, and an intact urethra. Urodynamic analysis was within normal limits except for a decrease in bladder volume. An intact urethral lumen without any strictures or fibrosis was demonstrated histopathologically. No calculus, mucus formation or urinary tract infection was observed in the late postoperative period. Fertility problems were noted in male rabbits. This animal experiment suggested that the pedicled appendiceal flap technique could be used for the treatment of severe forms of posterior urethral injuries.

Animals↗

PubMed2004

Patterns of low and lowest-low fertility in Europe.

In this paper we conduct descriptive aggregate analyses to revisit the relationship of low and lowest-low period fertility to cohort fertility and key fertility-related behaviour such as leaving the parental home, marriage, and women's labour force participation. Our analyses show that the cross-country correlations in Europe between total fertility and the total first marriage rate, the proportion of extramarital births, and the labour force participation of women reversed during the period from 1975 to 1999. By the end of the 1990s there was also no longer evidence that divorce levels were negatively associated with fertility levels. We argue that lowest-low fertility has been particularly associated with a 'falling behind' of cohort fertility at higher birth orders and later ages. From these analyses we conclude that the emergence of lowest-low fertility during the 1990s was accompanied by a disruption or even a reversal of many well-known relationships that have been used to explain cross-country differences in fertility patterns.

Adult↗

PubMed1994

[Decreasing total fertility rates in Europe].

"Due to an almost overall decrease during the last four decades total (period) fertility rates have reached values below the replacement level of 2.07 in most European countries. Only in Albania (2.8 in 1991), on the Faroe Islands (2.7 in 1990) and Iceland (2.3 in 1992) the last known values are higher. In most other European countries values between 1.4 and 2.0 are registered, but in Italy, Spain and Germany the TFR is about 1.2. Especially in the former German Democratic Republic (0.7), San Marino and most northern Italian regions (1.0) the TFR is low." (SUMMARY IN ENG)

Birth Rate↗

PubMed1998

Sexual maturation and fertility of male and female mice exposed prenatally and postnatally to trivalent and hexavalent chromium compounds.

The reproductive toxicity of trivalent and hexavalent chromium compounds was investigated in male and female mice exposed to 1000 ppm chromium chloride and potassium dichromate via their mother during gestational and lactational periods. Fertility was reduced in male offspring exposed to either trivalent or hexavalent chromium compounds. Body weights and weights of testes, seminal vesicles and preputial glands were reduced in trivalent-exposed male offspring. The exposure of female mice offspring to trivalent and hexavalent chromium compounds delayed sexual maturation. Fertility was reduced in female offspring exposed to either trivalent or hexavalent chromium compounds. The exposure of female mice to hexavalent chromium compound reduced the number of implantations and viable fetuses respectively. Body weight and weights of ovaries and uteri were reduced in trivalent-exposed female offspring. The results indicate that under our experimental conditions, the exposure of male and female mice offspring to either trivalent or hexavalent chromium compounds during gestational and lactational periods impair reproductive functions and fertility in adulthood.

Animals↗

PubMed1978

A hypothesis on the declining dizygotic twinning rates in developed countries.

1) There has been an unexplained drop in dizygotic twinning rates during the past 15--20 years in all the developed countries for which data are available. In this note an explanation is offered for this decline. 2) There has been a decline in birth rates in almost all developed countries over much of the same period. 3) There is good evidence that in recent years there has been a decline in sperm counts--at any rate in the United States. 4) It is suggested here that this decline in sperm counts has been responsible for a decline in the probability that coitus in the fertile period will result in fertilization of the ovum. It is hypothesized that this decline is responsible for the decline in dizygotic twinning rates and--partially--for the decline in birth rates.

Birth Rate↗

PubMed1999

The role of fertility restoration in the maintenance of the inversion In(2L)t polymorphism in drosophila melanogaster.

In order to explain the worldwide latitudinal distribution and seasonal fluctuations in In(2L)t frequencies in Drosophila melanogaster, fitness differences among In(2L)t and Standard (ST ) homo- and heterokaryotypes under high-temperature conditions were determined. Viabilities were measured for high-temperature treatment started at different juvenile stages. The capacity to restore fertility after high-temperature treatment was measured for adults and juveniles. Furthermore, genetic adaptation for increased temperature resistance for these traits was determined for strains which were reared at 33 degrees C for 10 generations. Whereas larva-pupa survival rates were high, highest juvenile mortalities and strongest karyotypic effects were observed during the pupal stage when preceding larval stages were reared at 33 degrees C. ST karyotypes showed lowest viabilities. Although mating rate was hardly influenced, sterility was induced for females and males after high-temperature treatment of adults as well as juveniles. Subsequent transfer to 25 degrees C, however, resulted in restored fertility in some of the individuals, depending on the length of the recovery period. Fertility restoration was significantly higher for heterokaryotype males and females. Heterokaryotype superiority for restored fertility as well as for viability was positively correlated with severity of the treatment. Ten generations of selection at 33 degrees C resulted in significant improvement of juvenile survival and fertility restoration for all karyotypes. These fitness components were positively correlated (r=0.91; P < 0.001), which might suggest pleiotropic effects. It is concluded that the capacity to restore fertility after heat stress is an important fitness component, especially with respect to the In(2L)t polymorphism. The observed heterokaryotypic superiority fits with the idea that the latitudinal distribution of In(2L)t frequencies is maintained by balancing selection, with equilibrium values decreasing with latitude.

Animals↗

PubMed1988

Caffeine promotes in vitro fertilization of mouse ova within 15 minutes.

Epididymal sperm were collected from C57Bl6/J X DBA2/J (B6D2) males and allowed to capacitate for 2 hr. When cumulus-free oocytes were exposed to sperm for 15 min in either the presence (6.0 mM) or absence of caffeine, fertilization did not occur. However, when cumulus cells were left intact, 23% of oocytes were fertilized in caffeine-free medium and 62% in caffeine-containing medium. When cumulus-free oocytes were incubated with sperm for 30 min, none was fertilized in the absence of caffeine, but 33% were fertilized when 6.0 mM caffeine was present (P less than .02). These effects of caffeine were on the sperm, as sperm exposed to caffeine and then coincubated with oocytes for 15 min in essentially caffeine-free media fertilized a similar percent of oocytes (93%) as when sperm and oocytes were exposed to caffeine during the fertilization period (86%). When sperm were capacitated in caffeine-containing medium, the percentage of ova fertilized was similar to capacitation without caffeine. We conclude that both cumulus cells and caffeine speed up the fertilization process with mouse gametes and that the effect of caffeine is on the sperm, but not due to more rapid capacitation.

Animals↗

PubMed2003

Effects of age on hormonal and ultrasound markers of ovarian reserve in Chinese women with proven fertility.

BACKGROUND: A woman's fertility is remarkably reduced with increasing age. Reproductive age can be assessed by a number of ovarian reserve tests. There are very few studies addressing the effects of age on these markers in fertile women, especially in Asia. METHODS: On the second to fourth day of the menstrual period, fertile Chinese women with regular monthly cycles and no history of ovarian surgery underwent a transvaginal scan with colour Doppler to determine ovarian volume, total antral follicle count (AFC) and mean peak systolic velocity (PSV) of ovarian stromal blood flow, and their serum FSH and inhibin B levels were checked. RESULTS: Out of 145 women scanned, 119 were included in the final analysis. AFC is the only ovarian reserve marker that was significantly different among four age groups (</=20, 21-30, 31-40 and >40 years). AFC had the best correlation with the age of the women, followed by FSH level and ovarian volume. The decline of AFC with age was 3.8% per year (95% confidence interval 2.7-4.9%) in the conventional linear regression model, which was not improved by the biphasic linear regression model. CONCLUSION: Of the parameters tested, AFC showed the best correlation with women's age and declined linearly at a rate of 3.8% per year.

Adolescent↗

PubMed2000

Using complete breastfeeding and lactational amenorrhoea as birth spacing methods.

The aim of this study was to evaluate the effectiveness of lactational amenorrhoea and to determine the relationship between extended breastfeeding and the return of fertility. Breastfeeding pattern, basal body temperature, cervical mucus, salivary ferning, vaginal blood discharge, frequency of sexual intercourse, and the presence of ovulation in the first cycle after the resumption of menses with ultrasonography were evaluated in 40 women. All subjects completed the study with only one case of incomplete breastfeeding. No pregnancies were observed. The mean number of feeding sessions and mean interval between sessions decreased significantly (p <0.01) during the first six months postpartum (7.5 +/- 1.3 after 60 days postpartum vs. 5.7 +/- 2.1 after 180 days, and 3.6 +/- 0.8 vs. 5.1 +/- 0.9, respectively). Eight women (20%) menstruated before weaning, but none had an adequate thermal shift, while 32 (80%) had their first vaginal bleeding after weaning with 12 (37.5%) registering an adequate thermal shift. Both basal body temperature and salivary ferning proved to be suggestive of ovarian activity, while mucus characteristics were not reliable in identifying fertile periods. Our study showed that breastfeeding associated with lactational amenorrhoea proved to be a good method of postpartum fertility control. Since the importance of supplementation is still debated, it is recommended that a "complete" breastfeeding program be used.

Adult↗

PubMed2006

High fertilization success in a surface-brooding Caribbean gorgonian.

Colonies of the Caribbean gorgonian Pseudopterogorgia elisabethae release eggs that are retained on the colony surface where they are fertilized and then develop. In December 2001, spawning on San Salvador Island, Bahamas, occurred over 6 d, with spawning by any one colony limited to 1-3 d. With the exception of the first and last days of the spawning period, fertilization success was high, often greater than 90%. Eggs collected in December 2001 had an overall fertilization success of more than 66%. At one site, the increase in fertilization after the first day of spawning correlated with male spawning, but male gonad index was a poor predictor of fertilization success. The number of male colonies close to a female was not correlated with fertilization success. Surface brooding is an efficient mechanism for "harvesting" sperm released upstream of female colonies. By maintaining their eggs at a single location, surface-brooding species can extend the period over which eggs are likely to encounter sperm. As a result, fertilization success is summed across the temporal variance in sperm availability, and the need for very high densities of sperm, with its concomitant risk of polyspermy, may be reduced.

Animals↗

PubMed1983

The relationship of tubal blockage, infertility of unknown cause, suspected male infertility, and endometriosis to success of in vitro fertilization and embryo transfer.

The success of in vitro fertilization (IVF) and embryo transfer has been examined with regard to five categories of infertility over a 2-year period. Fertilization rates in vitro were highest in women with bilateral tubal blockage and women treated for endometriosis. There was a significant reduction of approximately 13% in the fertilization rate of couples with idiopathic infertility and women who had failed to conceive after 12 cycles of artificial insemination by donor. A further substantial reduction in the fertilization rate occurred when the husband had low quality semen, particularly when no abnormality was detected in the wife. Repeated IVF in couples with idiopathic infertility eventually resulted in fertilization. It is recommended that donor spermatozoa not be used for cases of idiopathic infertility, but it may be needed in cases of poor semen quality. There were no differences in the pregnancy rates following embryo replacement in any of the groups studied, nor was there any detectable effect of age on fertilization or pregnancy rates up to the age of 44 years.

Adult↗

PubMed1991

Human cervical mucus: research update.

Evaluation of cervical mucus is a standard for determining the fertile period in natural family planning. Cervical mucus accepts, filters, prepares, and releases sperm for successful transport to the egg and fertilization. Recent scientific advances provide answers to how the mucus regulates fertility as its physical properties change during the menstrual cycle. Transmission electron microscopy reveals small interstices between mucus macromolecules relative to a sperm head. Thus advancing sperm must push aside or cut through the microstructure. The interstices are largest in the periovulatory phase of the cycle. Small magnetic spheres, comparable with the size of a sperm head, are now being used to study the physical properties of the mucus on the scale of individual sperm.

Cervix Mucus↗

PubMed1976

[Epidemiology of endometrial hyperplasia and adenocarcinoma].

In a retrospective study characteristics of 729 climacteric and postmenopausal women with hyperplasia and adenocarcinoma of the endometrium are compared with those of 82 women with atrophic endometrium and 96 women with carcinoma of the cervix. In a prospective study 225 women with glandular-cystic, adenomatous and atypical hyperplasia of the endometrium have been checked by a control-curettage within a period of two months until four years following the first diagnosis. Low parity, disturbances of menstruation with anovulatoric bleedings during fertility period, adipositas, hypertension and diabetes mellitus in climacteric and postmenopausal women indicate a high risk of carcinoma of the endometrium. Hyperplasias of the endometrium in climacteric women cannot be considered as precursors of corpus carcinoma. They are the result of a temporary hormonal dysfunction. Prophylactic hysterectomy, however, should be performed, if adenomatous or atypical hyperplasia appears in older postmenopausal women with the indicators of high risk of endometriumcarcinoma as mentioned above.

Adenocarcinoma↗

PubMed1985

The hormonal situation in the perimenopausal period.

Follicular function starts in the foetal ovary in the 20th week of gestation and continues until or shortly past the menopause. Luteal steroid production occurs only during the fertile period. After the menopause only stromal steroid production continues in the ovary and is probably increased by the increase in gonadotropin levels. The changes in hormonal levels and effects in the pre-, peri- and postmenopausal years are described as a function of these changes.

Adolescent↗

PubMed2005

Fertility in Kenya and Uganda: a comparative study of trends and determinants.

Between 1980 and 2000 total fertility in Kenya fell by about 40 per cent, from some eight births per woman to around five. During the same period, fertility in Uganda declined by less than 10 per cent. An analysis of the proximate determinants shows that the difference was due primarily to greater contraceptive use in Kenya, though in Uganda there was also a reduction in pathological sterility. The Demographic and Health Surveys show that women in Kenya wanted fewer children than those in Uganda, but that in Uganda there was also a greater unmet need for contraception. We suggest that these differences may be attributed, in part at least, first, to the divergent paths of economic development followed by the two countries after Independence; and, second, to the Kenya Government's active promotion of family planning through the health services, which the Uganda Government did not promote until 1995.

Contraception↗

PubMed1999

Some considerations on the human Leydig cell (immunohistochemical observations).

The presence and functional activity of human Leydig cells were assessed at diverse stages of human gonad development in biopsies obtained from healthy controls and subjects with cryptorchidism or varicocele. In our investigation primary antibodies directed against vimentin and testosterone by immunoperoxidase technique of biotin-streptoavidin amplified system were used to analyse immunoreactive sites. The antivimentin antibody is, in general, a specific marker of cells of mesenchymal origin and also detects the presence of Leydig cells, while the antitestosterone antibody shows the functional status of these cells. The immunohistochemical examination revealed the presence of two main populations in the testes of healthy subjects: a foetal and an adult population. The former appeared during the embryonal period, remained throughout foetal life and disappeared after birth. The latter was detected just before puberty and was present for the whole fertile period. Leydig cells in testes affected by cryptorchidism or varicocele showed normal morphology when the disease did not involve intertubular connective tissue. Leydig cells disappeared or were very altered when intertubular tissue was seriously damaged. The intertubular damage was observed in some children with cryptorchidism after prolonged hormonal therapy and in some adults with long term cryptorchidism or varicocele. These observations confirm that if hormonal therapy fails to bring the testis down into the scrotum surgery is required at first years of the life and that in selected cases the varicocele vascular alteration must be surgically corrected.

Adolescent↗