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Results for “Fertility Pattern Method”

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PubMed2005

A saturation screen for cis-acting regulatory DNA in the Hox genes of Ciona intestinalis.

A screen for the systematic identification of cis-regulatory elements within large (>100 kb) genomic domains containing Hox genes was performed by using the basal chordate Ciona intestinalis. Randomly generated DNA fragments from bacterial artificial chromosomes containing two clusters of Hox genes were inserted into a vector upstream of a minimal promoter and lacZ reporter gene. A total of 222 resultant fusion genes were separately electroporated into fertilized eggs, and their regulatory activities were monitored in larvae. In sum, 21 separable cis-regulatory elements were found. These include eight Hox linked domains that drive expression in nested anterior-posterior domains of ectodermally derived tissues. In addition to vertebrate-like CNS regulation, the discovery of cis-regulatory domains that drive epidermal transcription suggests that C. intestinalis has arthropod-like Hox patterning in the epidermis.

Animals↗

PubMed2006

Modelling number of services per conception of Japanese Black cattle by random regression.

Repeated records of number of services per conception (NSC) were collected on 607 Japanese Black cows. Data were analysed by random regression (RRM) and multiple trait (MTM) models, considering NSC in each parity as a separate trait. The chosen RRM included additive genetic and permanent environmental effects fitted with a third-order Legendre polynomials of parity. Heritabilities (h2) estimated by RRM decreased along the NSC trajectory from 0.15 in the first parity to 0.04 in the sixth parity and then increased up to 0.22 in the 10th parity. The corresponding estimates obtained by MTM ranged between 0.04 in parity 9 and 0.13 in parity 1. Permanent environmental proportions (p2) of the total phenotypic variance estimated by RRM showed similar pattern and magnitude to those of h2 estimated by the same method. On the contrary, the p2 estimated by MTM ranged between 0.04 in the first parity and 0.11 in the 10th parity. Additive genetic (r(G)), permanent environmental (r(P)) and phenotypic (r(PH)) correlations were also estimated. The values estimated by RRM between adjacent parities were higher than those of parities far apart. The corresponding values estimated by MTM were lower than those estimated by RRM with no certain trend. The results indicated that NSC in heifers is more heritable than NSC in cows with different parities. Reproductive traits are economically important traits and hence, they should be considered in breeding goals.

Analysis of Variance↗

PubMed2006

Population dynamics of sporogony for Plasmodium vivax parasites from western Thailand developing within three species of colonized Anopheles mosquitoes.

BACKGROUND: The population dynamics of Plasmodium sporogony within mosquitoes consists of an early phase where parasite abundance decreases during the transition from gametocyte to oocyst, an intermediate phase where parasite abundance remains static as oocysts, and a later phase where parasite abundance increases during the release of progeny sporozoites from oocysts. Sporogonic development is complete when sporozoites invade the mosquito salivary glands. The dynamics and efficiency of this developmental sequence were determined in laboratory strains of Anopheles dirus, Anopheles minimus and Anopheles sawadwongporni mosquitoes for Plasmodium vivax parasites circulating naturally in western Thailand. METHODS: Mosquitoes were fed blood from 20 symptomatic Thai adults via membrane feeders. Absolute densities were estimated for macrogametocytes, round stages (= female gametes/zygotes), ookinetes, oocysts, haemolymph sporozoites and salivary gland sporozoites. From these census data, five aspects of population dynamics were analysed; 1) changes in life-stage prevalence during early sporogony, 2) kinetics of life-stage formation, 3) efficiency of life-stage transitions, 4) density relationships between successive life-stages, and 5) parasite aggregation patterns. RESULTS: There was no difference among the three mosquito species tested in total losses incurred by P. vivax populations during early sporogony. Averaged across all infections, parasite populations incurred a 68-fold loss in abundance, with losses of ca. 19-fold, 2-fold and 2-fold at the first (= gametogenesis/fertilization), second (= round stage transformation), and third (= ookinete migration) life-stage transitions, respectively. However, total losses varied widely among infections, ranging from 6-fold to over 2,000-fold loss. Losses during gametogenesis/fertilization accounted for most of this variability, indicating that gametocytes originating from some volunteers were more fertile than those from other volunteers. Although reasons for such variability were not determined, gametocyte fertility was not correlated with blood haematocrit, asexual parasitaemia, gametocyte density or gametocyte sex ratio. Round stages and ookinetes were present in mosquito midguts for up to 48 hours and development was asynchronous. Parasite losses during fertilization and round stage differentiation were more influenced by factors intrinsic to the parasite and/or factors in the blood, whereas ookinete losses were more strongly influenced by mosquito factors. Oocysts released sporozoites on days 12 to 14, but even by day 22 many oocysts were still present on the midgut. The per capita production was estimated to be approximately 500 sporozoites per oocyst and approximately 75% of the sporozoites released into the haemocoel successfully invaded the salivary glands. CONCLUSION: The major developmental bottleneck in early sporogony occurred during the transition from macrogametocyte to round stage. Sporozoite invasion into the salivary glands was very efficient. Information on the natural population dynamics of sporogony within malaria-endemic areas may benefit intervention strategies that target early sporogony (e.g., transmission blocking vaccines, transgenic mosquitoes).

Adult↗

PubMed2003

Pregnancy rate fluctuations during routine work in an assisted reproduction technology unit.

BACKGROUND: Fluctuations in spontaneous pregnancy rates have been observed in the general population. The purpose of this study was to evaluate whether pregnancy rates fluctuate over time in a homogeneous assisted reproduction treatment unit. METHODS: The study sample consisted of 3522 consecutive assisted reproduction cycles conducted from January 1996 to December 1999. Only fresh cycles in women <41 years old were included. All pertinent clinical data were prospectively collected on a computerized database and analysed at the end of the study. RESULTS: Throughout the 4 years of the study, monthly pregnancy rates fluctuated between 10.5 and 34.1% (mean 21.4%) per cycle, and between 13.6 and 41% (mean 27.26%) per transfer. These fluctuations did not follow any specific seasonal pattern. CONCLUSION: During routine work in an assisted reproduction treatment unit, there are random fluctuations in the pregnancy rate. This factor should be considered in studies performed in a specific time-period.

Female↗

PubMed1997

Episodic variations of prolactin, thyroid-stimulating hormone, luteinizing hormone, melatonin and cortisol in infertile women with subclinical hypothyroidism.

Preliminary data have suggested that female infertility due to corpus luteum insufficiency may be caused by subclinical hypothyroidism [exaggerated thyroid-stimulating hormone (TSH) response to thyrotrophin-releasing hormone (TRH) stimulation]. L-Thyroxine supplementation has been recommended to achieve pregnancies in subclinical hypothyroid women. This controlled study was carried out in order to investigate the biochemical diagnosis of subclinical hypothyroidism as a possible infertility factor. Five infertile patients (aged 25-36 years) with subclinical hypothyroidism (n = 4, stimulated TSH >20 microU/ml) or primary hypothyroidism (n = 1) and five healthy controls (aged 22-39 years) with normal thyroid function (stimulated TSH <15 microU/ml), regular cycles and no history of infertility were studied in the early follicular phase. In the pre-study evaluation, eight of 23 volunteers (34.8%) had to be excluded because of subclinical hypothyroidism with stimulated TSH values (TSHs) >15 microU/ml. Cycle function of patients and controls was compared by the method of LH pulse pattern analysis. Therefore blood samples were drawn every 10 min during a 24 h period. Sleep was recorded from midnight to 7 a.m. Repetition of the TRH tests at the end of the 24 h blood sampling period confirmed the difference in stimulated TSH values of the two study groups. Pulse analysis for luteinizing hormone (LH), TSH and prolactin showed no differences between patients and controls for pulse frequency, amplitude, height, length, area under curve (AUC) and the 24 h mean. Even the hypothyroid patient had a normal LH pulse pattern. Additional measurement of melatonin in pooled sera every 30 min gave the well-documented diurnal profiles during day and night for both groups. Patients had significantly higher melatonin values at seven time points during the night. Peaks for LH, TSH, prolactin and cortisol were correlated with the sleep stages wake, rapid eye movement, 1 + 2 and 3 + 4. We concluded that corpus luteum insufficiency in female infertility cannot be explained by subclinical hypothyroidism and thus should not be treated with L-thyroxine for fertility reasons.

Adult↗

PubMed1993

Cytoplasmic inheritance and its effects on development and performance.

In contrast to nuclear inheritance, cytoplasmic inheritance in mammals is derived mostly, if not exclusively, from the maternal line. Mitochondria, and their DNA molecules (mtDNA), are the genetic units of this method of inheritance. Mammalian mtDNA codes for 13 enzymes used in the mitochondrial energy-generating pathway, oxidative phosphorylation, 22 tRNAs and two rRNAs. Although all transcripts of mtDNA and their translational products remain in the mitochondria, most proteins used in mitochondria are from nuclear DNA and are imported after synthesis on cytoplasmic ribosomes. Spermatozoa introduce a small number of mitochondria into the cytoplasm of the egg at fertilization, which appear to be digested soon after penetration. Although the paternal contribution of mtDNA to the offspring is not believed to occur in mammals, some interspecific crosses have suggested that it does occur. Experiments with animals derived from reconstituted embryos, using nuclear or cytoplasmic transplantations, suggest that nuclear-mitochondrial interactions are important but not essential in the survival and replication of exogenous mitochondria introduced into the egg. As the levels of heteroplasmy varied in several tissues of animals derived from reconstituted embryos, it is suggested that differential partitioning of mitochondria occurs during embryogenesis. Mitochondrial morphology changes substantially during oogenesis and throughout early cleavage stages. Somatic morphology and normal replication patterns are regained at the blastocyst stage. In pig oocytes and embryos, mitochondria aggregate and are closely associated with endoplasmic reticulum, lipid granules and large vesicles. Although the direct correlation of mitochondrial genes with reproductive traits is still unclear, some human degenerative diseases and performance traits in cattle can be related directly to specific mtDNA polymorphisms. In pigs, reciprocal-cross comparisons have indicated greater offspring parent similarity with dam than sire for lean:fat ratio. A difference was also observed for oxygen consumption and oxidative phosphorylation, but not for anaerobic energy metabolism, in a pig reciprocal-cross experiment. Information on the transmission of mtDNA and its effects on performance will have many implications not only for our understanding of mitochondrial genetics but also for the increased productivity of animals. There are also potential ramifications to the animal cloning industry.

Animals↗

PubMed1991

Time course and pattern of cortical granule breakdown in hamster eggs after sperm fusion.

We have determined the temporal relationship between sperm fusion and cortical granule breakdown in the hamster egg. Sperm fusion was determined by the Hoechst-transfer method (Stewart-Savage and Bavister: Dev Biol 128:150-157, 1988), and cortical granules were visualized with fluorescein isothiocynate-conjugated Lens culinaris agglutinin (Cherr et al. J Exp Zool 246:81-93, 1988). By 55 min after insemination, there was an 85% reduction in the density of cortical granules (fewer than four granules/100 microns2). Taking this value as the completion of the cortical reaction, analysis of the data indicate that the cortical reaction was completed 9 min after sperm fusion and 3 min after the formation of the zona and cell surface blocks to polyspermy. There was no obvious spatial pattern of granule loss in eggs that had a Hoechst-positive sperm but had not completed the cortical reaction.

Animals↗

PubMed1975

D-norgestrel slow-releasing T device as an intrauterine contraceptive.

A D-norgestrel slow-releasing T device was tried as an IUD in 100 fertile multiparous women for 6 months. The preliminary results were very encouraging. Not a single case of unintended pregnancy or removal due to excessive pain and bleeding was reported. The menstrual patterns and amounts of blood loss during menses did not reveal any marked variations. 3-H-D-norgestrel was used to study the in vitro release rate of D-norgestrel. The in vivo release rate was studied with the use of horseshoe-shaped silicone rubber capsules loaded with D-norgestrel as a temporary device. The uptake of intrauterine H-D-norgestrel in the circulation and genital tissues was estimated in two women.

Female↗

PubMed1990

Endometrial assessment in a group of infertile women on stimulated cycles for IVF: immunohistochemical findings.

An immunohistochemical assessment of the endometrium was carried out in a group of IVF patients on stimulated cycles, in order to evaluate this technique against standard histological methods and to consider its application in a clinical situation. Monoclonal antibodies to the two cycle-dependent proteins: pregnancy associated endometrial alpha 2-globulin (alpha 2-PEG) and 24K (a protein originally isolated from an oestrogen-dependent breast tumour line, MCF-7) were used in the experiment. Immunohistochemical results concerning the effect of drug stimulation, age and date of biopsy on the secretory state of the endometrium revealed trends which were consistent with previous histological data, helping to confirm the value of this new technique. In addition, several specimens were found to have a normal, i.e. in phase, histological appearance but to have an atypical pattern of protein secretion. These observations suggest that biochemical monitoring of the uterus should be used in conjunction with routine histological dating.

Adult↗

PubMed2003

Ovarian follicle growth and consequences for fertility in sheep.

Understanding the pattern of ovarian follicle development is seen as an important step leading to the development of techniques that maximise fertility in sheep. Repeated observations of the growth of individual follicles have led to the understanding that follicles develop in a wave-like pattern during the oestrous cycle, with two to four waves per cycle being the most common. The ease with which follicle waves are described seems to depend on the their frequency and the number of follicles per wave. There is evidence for the largest follicle(s) of a follicle wave inhibiting the development of other follicles; however, in some cases this is not apparent as other follicle waves emerge when a previous large, healthy follicle is still present. Follicle development can be manipulated using exogenous gonadotrophins or progestagens and these have been shown to alter the number or age profile of developing follicles. The ovulation of aged follicles in cattle clearly has a detrimental effect on fertility, but this relationship is less clear and seems to be less critical in sheep. Recent findings at the molecular level show that the bone morphogenetic proteins (BMP) and their receptors are critically involved in the control of ovulation rate, but fully understanding their mechanism remains to be described. This highlights the potential for the integration of molecular and physiological findings to better develop methods to manipulate follicle development and reproduction in sheep.

Anestrus↗

PubMed2002

[Genetics study on photo- and thermo-sensitive genic male sterility of indica rice (O. satival L.)].

The sterility segregation and its genetic patterns of indica P(T)GMS rice were analyzed mainly based on the investigation of bagged seed-set of individuals in reciprocal F2 population from the crosses between P(T)GMS lines of different origin and typical indica conventional varieties of different ecotype under long day-length and high temperature condition by using the software of the maximum likelihood method. The results showed that the sterility of Annong S-1, Hengnong S-1, and W6154S, of which the sterility alteration was mainly induced by temperature fluctuation, was controlled by one major recessive gene. But the sterility of W7415S was controlled by more than two major recessive genes. Apart from the major recessive gene, there was a group of polygenes in controlling of the sterility segregation in F2 population. Moreover, the polygenic variance was different from line to line. It implied that the polygenes of W6154S or W7415S was far more complicated than that of Annong S-1 and Hengnong S-1 according to the maximum likelihood method. All the conventional indica varieties of different ecotypes possessed the major dominant fertility genes. Meanwhile, the genetic background in different ecotype conventional varieties, the essentiality of which lies in the existence of polygenes, was different and influenced the major gene expression deeply. It was also indicated that genetic background of middle-season variety Nanjing 11 was more complicated than that of early-season variety Erjiuqing and late-season variety GER-1 as well. Finally, the differences of drift in critical temperature inducing male sterility of P(T)GMS lines (for short term DCT) and the strategy of breeding practically usable P(T)GMS line with slighter DCT were discussed in the paper.

Crosses, Genetic↗

PubMed2004

Metformin therapy in women with polycystic ovary syndrome.

OBJECTIVE: To determine the clinical, biochemical, hormonal, and ultrasonographic effects of 6 months of metformin therapy in women with polycystic ovary syndrome (PCOS) and compare with pretherapy parameters. METHOD: 50 Indian women with PCOS, 25 unmarried and 25 married, infertile women, were enrolled in this prospective clinical study. After a baseline workup, including body mass index (BMI), waist hip ratio (WHR), Ferriman Gallwey hirsutism scoring, menstrual pattern, levels of fasting insulin, lipids, oral glucose tolerance test (OGTT), serum gonadotropins, estradiol (E2), testosterone, androstenedione, sex hormone binding globulin (SHBG), and dehydroepiandrosterone sulphate (DHEAS), patients were given 1000 gm of metformin for 6 months and then reevaluated. RESULT: In 41 of 50 women who completed treatment, significant improvement in BMI, WHR, menstrual cyclicity (80.5%), ovulation rate (66%), and pregnancy rate (28%) was noted. Statistically significant decrease in lutenising hormone (LH) and LH/FSH ratio with an increase in follicle stimulating hormone (FSH) levels were seen. Levels of high-density lipoprotein (HDL) cholesterol (Chol) increased along with a decrease in total cholesterol. Improvement was noted in ovarian volume, stromal thickness, and number of follicles. There was no change in hirsutism, acne, levels of other sex steroid hormones, and lipids. CONCLUSION: A 6-month course of metformin therapy may improve menstrual cyclicity and fertility in women with PCOS.

Adolescent↗

PubMed1991

The Butajira rural health project in Ethiopia: mortality pattern of the under fives.

A total of 492 deaths of children below 5 years of age were registered during a 2-year period of demographic surveillance in a rural population of Ethiopia, where an epidemiologic study base population of 28,780 individuals was established in 1987. Data were collected by lay-reporters using a verbal autopsy method. The under-five cumulative mortality rate was 209 per 1000 children. When sub-divided into infants and children 1-4 years, the respective yearly mortality rates were 101 and 32.3 per 1000. There were considerable variations within the district by Peasants' Associations. Rural Lowlands experienced the highest mortality rates, especially for children 1-4 years. Mortality trends over a 2-year period indicate a significant increase for the child population, but not for infants. Similar trends were observed for boys and girls although the rates for boys were generally higher especially during infancy. More deaths occurred in the months of April, June, and July, and October and November indicating two peak seasons in both years. More deaths occurred in Peasant's Associations that were furthest from the health centre. Major probable causes of death were acute respiratory infections, measles, and diarrhoea. It is concluded that even in rural areas of a developing country it is possible to collect from mothers the much needed and valid fertility and mortality data through epidemiological surveillance by using lay-reporters.

Age Factors↗

PubMed2003

Substrate specificity of glutaminyl cyclases from plants and animals.

Glutaminyl cyclases (QC) catalyze the intramolecular cyclization of N-terminal glutamine residues of peptides and proteins. For a comparison of the substrate specificity of human and papaya QC enzymes, a novel continuous assay was established by adapting an existing discontinuous method. Specificity constants (kcat/Km) of dipeptides and dipeptide surrogates were higher for plant QC, whereas the selectivity for oligopeptides was similar for both enzymes. However, only the specificity constants of mammalian QC were dependent on size and composition of the substrates. Specificity constants of both enzymes were equally pH-dependent in the acidic pH-region, revealing a pKa value identical to the pKa of the substrate, suggesting similarities in the substrate conversion mode. Accordingly, both QCs converted the L-beta homoglutaminyl residue in the peptide H-beta homoGln-Phe-Lys-Arg-Leu-Ala-NH2 and the glutaminyl residues of the branched peptide H-Gln-Lys(Gln)-Arg-Leu-Ala-NH2 as well as the partially cyclized peptide H-Gln-cyclo(N epsilon-Lys-Arg-Pro-Ala-Gly-Phe). In contrast, only QC from C. papaya was able to cyclize a methylated glutamine residue, while this compound did not even inhibit human QC-catalysis, suggesting distinct substrate recognition pattern. The conversion of the potential physiological substrates [Gln1]-gastrin, [Gln1]-neurotensin and [Gln1]-fertilization promoting peptide indicates that human QC may play a key role in posttranslational modification of most if not all pGlu-containing hormones.

Amino Acids↗

PubMed1986

Fluid in the female pelvis: cyclic patterns.

A total of 254 pelvic sonograms were performed on 40 volunteers in order to determine a cyclic pattern, if any, of free fluid in the pelvis in asymptomatic premenopausal women. Free fluid was observed during all phases of the menstrual cycle. The highest percentage of positive-for-fluid sonograms was observed within 5 days preceding onset of menses in both oral contraceptive users and non-oral contraceptive users. The second highest percentage was observed between days 13 and 21 in non-oral contraceptive users.

Adolescent↗

PubMed1998

Aluminum Phenylphosphonates: A Fertile Family of Compounds.

Six aluminum phenylphosphonates have been synthesized depending upon the synthetic conditions: Al(2)(O(3)PC(6)H(5))(3).2H(2)O (I), Al(2)(O(3)PC(6)H(5))(3) (II), alpha-Al(HO(3)PC(6)H(5))(O(3)PC(6)H(5)).H(2)O (III), beta-Al(HO(3)PC(6)H(5))(O(3)PC(6)H(5)).H(2)O (IV), Al(HO(3)PC(6)H(5))(3).H(2)O (V), and Al(OH)(O(3)PC(6)H(5)) (VI). Thermal analysis, X-ray powder thermodiffractometry, IR spectroscopy, and (27)Al and (31)P MAS NMR data have been obtained to study the structure and thermal stability of these materials. III crystallizes in the orthorhombic system, space group Pbca, with a = 9.7952(1) Å, b = 29.3878(4) Å, c = 9.3537(3) Å, and Z = 8. The structure was solved ab initio, from synchrotron data (lambda approximately 0.4 Å), using direct methods, and refined by Rietveld methods. The final agreement factors were R(wP) = 6.73%, R(P) = 5.24%, and R(F)() = 6.8%. The compound is layered with the aluminum atoms in an octahedral environment of oxygens and two crystallographically independent phosphonate groups, one being protonated. The powder patterns of V and VI have been indexed, and the experimental observations are consistent with layered structures. The unit cell of V contains one octahedral site for Al and three tetrahedral sites for P. Phosphonate I seems to have a three-dimensional tubular structure with aluminum atoms in both octahedral and tetrahedral environments and phosphorus atoms in three different types of sites.

Journal Article↗

PubMed2005

Inter-population variations in concentrations, determinants of and correlations between 2,2',4,4',5,5'-hexachlorobiphenyl (CB-153) and 1,1-dichloro-2,2-bis (p-chlorophenyl)-ethylene (p,p'-DDE): a cross-sectional study of 3161 men and women from Inuit and European populations.

BACKGROUND: The study is part of a collaborative project (Inuendo), aiming to assess the impact of dietary persistent organochlorine pollutants (POPs) on human fertility. The aims with the present study are to analyze inter-population variations in serum concentrations of 2,2',4,4',5,5'-hexachlorobiphenyl (CB-153) and 1,1-dichloro-2,2-bis (p-chlorophenyl)-ethylene (p,p'-DDE), to assess inter-population variations in biomarker correlations, and to evaluate the relative impact of different determinants for the inter-individual variations in POP-biomarkers. METHOD: In study populations of 3161 adults, comprising Greenlandic Inuits, Swedish fishermen and their wives, and inhabitants from Warsaw, Poland and Kharkiv, Ukraine, serum concentrations of CB-153 and p,p'-DDE, were analysed by gas chromatography-mass spectrometry. RESULTS: The median serum concentrations of CB-153 were for male and female Inuits 200 and 110, for Swedish fishermen 190 and their wives 84, for Kharkiv men and women 44 and 27, and for Warsaw men and women 17 and 11 ng/g lipids, respectively. The median serum concentrations of p,p'-DDE were for Kharkiv men and women 930 and 650, for male and female Inuits 560 and 300, for Warsaw men and women 530 and 380, and for Swedish fishermen 240 and their wives 140 ng/g lipids, respectively. The correlation coefficients between CB-153 and p,p'-DDE varied between 0.19 and 0.92, with the highest correlation among Inuits and the lowest among men from Warsaw. Men had averagely higher serum concentrations of CB-153 and p,p'-DDE, and there were positive associations between age and the POP-biomarkers, whereas the associations with BMI and smoking were inconsistent. Dietary seafood was of importance only in the Inuit and Swedish populations. CONCLUSION: CB-153 concentrations were much higher in Inuits and Swedish fishermen's populations than in the populations from Eastern Europe, whereas the pattern was different for p,p'-DDE showing highest concentrations in the Kharkiv population. The correlations between the POP-biomarkers varied considerably between the populations, underlining that exposure sources differ and that the choice of representative biomarkers of overall POP exposure has to be based on an analysis of the specific exposure situation for each population. Age and gender were consistent determinants of serum POPs; seafood was of importance only in the Inuit and Swedish populations.

Adult↗

PubMed1997

[Endometrial interference of synthetic estrogens in fertility regulation.Is it necessary to interfere with the antiovulatory mechanism at the central nervous system level in order to obtain contraception?].

For some time the anti-ovulatory activity of certain estrogen/progestagen preparations was the main approach in fertility control. Up to date a drastic dosage reduction of both steroid hormones has been accomplished ameliorating the side effects on the one hand, and being active compounds as contraceptives, in the other. Currently, there are a wide variety of oral contraceptives available with a variety of estrogen doses combined with different progestagens. The estrogen content is a high as 80 micrograms and as low as 20 micrograms, moreover, such formulations are prescribed beginning the 1st or the 5th day of the menstrual cycle. By studying plasma and endometrial samples simultaneously obtained from chronic oral contraceptive users taking either 30 micrograms or 50 in such pills; a 17-beta-estradiol pattern was attained as that seen during follicular maturation in the ovulatory cycle only women under the lower dose of synthetic estrogen. However, in the endometrium such a cyclicity did not take place; in parallel circulating progesterone in both groups never reach levels greater than 5.0 ng/ml. Results offer to find a local critical period during the ovulatory menstrual cycle to achieve with much lower hormonal dosages a different approach in future methods of contraception.

Contraception↗