首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 46 毫秒
1.
ObjectiveTo compare the effectiveness of different screening policies for the antenatal detection of Down''s syndrome.DesignRetrospective six year survey.SettingMaternity units of eight districts.ParticipantsWomen who completed their pregnancies between 1 January 1994 and 31 December 1999 (155 501 deliveries).Results335 cases of Down''s syndrome were identified, 323 in continuing pregnancies or liveborn children. Of these, 171 were identified antenatally. Seven different screening policies were used, in three principal groups: serum screening offered to all mothers, maternal age with serum screening or nuchal translucency available to limited groups, and maternal age combined with anomaly scans. The districts that used serum screening detected 57%, those using maternal age plus serum or nuchal translucency screening 52%, and those using a maternal age of ⩾35 and anomaly scans detected 54%. The least successful district, which offered amniocentesis only to women aged over 37 years, detected only 31%. If amniocentesis had been offered from 35 years, as in all other districts, the detection rate would have risen to 54%. Across the region 15% (range 12-20%) of pregnant women were 35 years or more at delivery, and 58% (33-69%) of infants with Down''s syndrome were born to women in this age range.ConclusionsCurrent additional serum or nuchal translucency screening techniques for antenatal detection of Down''s syndrome are less advantageous than previously supposed. More pregnant women were aged over 35 than has been presumed in statistical models used in demonstration projects of serum screening and, as a result, the proportion of affected fetuses in this age group is much greater than predicted.

What is already known on this topic

Serum screening for Down''s syndrome has been presumed to be more effective than screening by maternal ageThere have been no controlled studies comparing serum screening with screening by maternal age, and its greater efficacy has been presumed from mathematical modelling, which assumed that only 5% of pregnant women were aged over 35 yearsThe modelling predicted that only 20-30% of cases of Down''s syndrome would arise in women aged over 35 and made no allowance for the effects of routine anomaly scanning

What this study adds

15% of pregnant women were aged over 35 years, more than double the 5-7% presumed in statistical models of screening58% of babies with Down''s syndrome were born to women aged 35 years or moreSerum screening and nuchal scanning did not achieve significantly higher antenatal detection rates of Down''s syndrome than the use of maternal age and routine anomaly scanning  相似文献   

2.
S Perreault  M Dorais  L Coupal  G Paradis  M R Joffres  S A Grover 《CMAJ》1999,160(10):1449-1455
OBJECTIVE: To compare the prevalence of modifiable risk factors for cardiovascular disease among hypertensive and nonhypertensive adults and to estimate the effect of treating hyperlipidemia or hypertension to reduce the risk of death from coronary artery disease. METHODS: The authors evaluated a sample of 7814 subjects aged 35-74 years free of clinical cardiovascular disease from the Canadian Heart Health Surveys to estimate the prevalence of cardiovascular risk factors. They identified hyperlipidemic subjects (ratio of total cholesterol to high-density lipoprotein cholesterol [total-C/HDL-C] 6.0 [corrected] or more for men and 5.0 [corrected] or more for women) and hypertensive subjects (systolic or diastolic blood pressure 160/90 mm Hg or greater, or receiving pharmacologic or nonpharmacologic treatment). A life expectancy model was used to estimate the rate of death from coronary artery disease following specific treatments. RESULTS: An elevated total-C/HDL-C ratio was significantly more common among hypertensive than nonhypertensive men aged 35-64 (rate ratio [RR] 1.56 for age 35-54, 1.28 for age 55-64) and among hypertensive than nonhypertensive women of all ages (RR 2.73 for age 35-54, 1.58 for age 55-64, 1.31 for age 65-74). Obesity and a sedentary lifestyle were also more common among hypertensive than among nonhypertensive subjects. According to the model, more deaths from coronary artery disease could be prevented among subjects with treated but uncontrolled hypertension by modifying lipids rather than by further reducing blood pressure for men aged 35-54 (reduction of 50 v. 29 deaths per 100,000) and 55-64 (reduction of 171 v. 104 deaths per 100,000) and for women aged 35-54 (reduction of 44 v. 39 deaths per 100,000). Starting antihypertensive therapy in subjects aged 35-74 with untreated hypertension would achieve a greater net reduction in deaths from coronary artery disease than would lipid lowering. Nonetheless, the benefits of lipid therapy were substantial: lipid intervention among hypertensive subjects aged 35-74 represented 36% of the total benefits of treating hyperlipidemia in the total hyperlipidemic population. INTERPRETATION: The clustering of hyperlipidemia and the potential benefits of treatment among hypertensive adults demonstrate the need for screening and treating other cardiovascular risk factors beyond simply controlling blood pressure.  相似文献   

3.
BackgroundA nonavalent human papillomavirus (HPV) vaccine has been licensed for use in women and men up to age 45 years in the United States. The cost-effectiveness of HPV vaccination for women and men aged 30 to 45 years in the context of cervical cancer screening practice was evaluated to inform national guidelines.Methods and findingsWe utilized 2 independent HPV microsimulation models to evaluate the cost-effectiveness of extending the upper age limit of HPV vaccination in women (from age 26 years) and men (from age 21 years) up to age 30, 35, 40, or 45 years. The models were empirically calibrated to reflect the burden of HPV and related cancers in the US population and used standardized inputs regarding historical and future vaccination uptake, vaccine efficacy, cervical cancer screening, and costs. Disease outcomes included cervical, anal, oropharyngeal, vulvar, vaginal, and penile cancers, as well as genital warts. Both models projected higher costs and greater health benefits as the upper age limit of HPV vaccination increased. Strategies of vaccinating females and males up to ages 30, 35, and 40 years were found to be less cost-effective than vaccinating up to age 45 years, which had an incremental cost-effectiveness ratio (ICER) greater than a commonly accepted upper threshold of $200,000 per quality-adjusted life year (QALY) gained. When including all HPV-related outcomes, the ICER for vaccinating up to age 45 years ranged from $315,700 to $440,600 per QALY gained. Assumptions regarding cervical screening compliance, vaccine costs, and the natural history of noncervical HPV-related cancers had major impacts on the cost-effectiveness of the vaccination strategies. Key limitations of the study were related to uncertainties in the data used to inform the models, including the timing of vaccine impact on noncervical cancers and vaccine efficacy at older ages.ConclusionsOur results from 2 independent models suggest that HPV vaccination for adult women and men aged 30 to 45 years is unlikely to represent good value for money in the US.

Jane Kim and co-workers estimate the potential cost-effectiveness of papillomavirus vaccination for adults aged 30-45 years in the United States.  相似文献   

4.
Between 1977 and 1985 there was a 65% increase in births to women aged 35 or more in England and Wales, but only a 15% increase in all births. Two factors of roughly equal importance were responsible for this differential increase. Firstly, the proportion of older women (35-44) among all women of reproductive age (15-44) increased from 28% in 1977 to 31% in 1985; and, secondly, in the same period the fertility rate for women aged 35-39 increased from 18·2 to 24·1 per 1000 and for women aged 40-44 from 4·1 to 4·6 per 1000.The increased fertility rate among older women is not due to an extension of the reproductive period but to a delay in childbearing. This delay was seen in women married only once and also in those who had remarried.As prenatal diagnosis for the exclusion of chromosome abnormalities is customarily offered to older mothers the increased numbers of women aged 35 or more and their increased fertility rate have important implications for the provision of obstetric and laboratory services. There were 51 859 live births to women aged 35 and over in 1985; the projected figure for 2001 is 85 000. If the use of prenatal diagnosis continues to increase facilities for about 70 000 prenatal cytogenetic analyses will be needed in 2001.  相似文献   

5.
Humans exhibit an unusual pattern of sexual behavior compared to other mammalian females. Women's extended sexuality has been hypothesized to be related to a variety of possible benefits, especially non-genetic reproductive benefits, such as securing male investment via reinforced pairbonds or paternity confusion. But sexual behavior also comes at a cost, particularly for pregnant women, in terms of energetic costs, potential disease, and possible harm to the fetus. We hypothesize, therefore, that sexual behavior in pregnant women should reflect adaptive strategies and that pregnant women will be particularly strategic about their sexual behavior in order to maximize potential benefits while minimizing potential costs. One hundred twelve pregnant women completed a survey of their partners' qualities and their sexual desires toward their primary partners and men other than their primary partners. Results showed that women's perceptions of relationship threat positively predicted sexual desire for primary partners, while their perceptions of their partner's investing qualities negatively predicted sexual desire for extra-pair mates. These qualities, as well as cues to partner's genetic quality and gestation age, also interacted in ways that suggest that pregnant women's sexual desires are sensitive to cues of future investment and relationship stability.  相似文献   

6.
《BMJ (Clinical research ed.)》1995,310(6987):1099-1104
OBJECTIVE--To determine the effectiveness of health checks, performed by nurses in primary care, in reducing risk factors for cardiovascular disease and cancer. DESIGN--Randomised controlled trial. SETTING--Five urban general practices in Bedfordshire. SUBJECTS--2205 men and women who were randomly allocated a first health check in 1989-90 and a re-examination in 1992-3 (the intervention group); 1916 men and women who were randomly allocated an initial health check in 1992-3 (the control group). All subjects were aged 35-64 at recruitment in 1989. MAIN OUTCOME MEASURES--Serum total cholesterol concentration, blood pressure, body mass index, and smoking prevalence (with biochemical validation of cessation); self reported dietary, exercise, and alcohol habits. RESULTS--Mean serum total cholesterol was 3.1% lower in the intervention group than controls (difference 0.19 mmol/l (95% confidence interval 0.12 to 0.26)); in women it was 4.5% lower (P < 0.0001) and in men 1.6% (P < 0.05), a significant difference between the sexes (P < 0.01). Self reported saturated fat intake was also significantly lower in the intervention group. Systolic and diastolic blood pressures and body mass index were respectively 1.9%, 1.9%, and 1.4% lower in the intervention group (P < 0.005 in all cases). There was a 3.9% (2.4 to 5.3) difference in the percentage of subjects with a cholesterol concentration > or = 8 mmol/l, but no significant differences in the number with diastolic blood pressure > or = 100 mm Hg or body mass index > or = 30 kg/m2. There was no significant difference between the two groups in prevalence of smoking or excessive alcohol use. Annual rechecks were no more effective than a single recheck at three years, but health checks led to a significant increase in visits to the nurse according to patients'' degree of cardiovascular risk. CONCLUSIONS--The benefits of health checks were sustained over three years. The main effects were to promote dietary change and reduce cholesterol concentrations; small differences in blood pressure may have been attributable to accommodation to measurement. The benefits of systematic health promotion in primary care are real, but must be weighed against the costs in relation to other priorities.  相似文献   

7.
OBJECTIVE--To derive demographic weightings to replace the existing system of prescribing units used in analysing prescribing by general practitioners in England. DESIGN--The prescribing data for one year from a sample of 90 practices in 80 family health service authority areas were used to calculate the relative frequency with which items were prescribed, for each sex, in nine age bands and for temporary residents. Data on the variation in cost per item by age and sex then allowed estimates to be made of the relative costs for these groups. Integer values for both the item based and cost based weightings were obtained by conversion to optimal integer scales. MAIN OUTCOME MEASURES--Item based and cost based weightings for each of the 18 age-sex groups and for temporary residents. The cost based weightings were considered more appropriate to the context in which the new system was to be used. RESULTS--Prescribing costs increased noticeably, for both sexes, in the middle years (ages 35-64). Compared with the existing system, the cost based weightings (ASTRO-PUs) gave greater weight to patients aged 45 and over, especially those in the 55-64 age band, at the expense of younger patients. Children under 5 received twice as many items as those aged 5-14, but the inexpensiveness of their drugs made the cost based weightings of the two groups equal. Similarly, women were generally given more items than men, but at a lower average cost per item, which reduced differences between the sexes in the cost based weightings. Costs for patients aged 75 and over, compared with those aged 65-74, were higher only for women. CONCLUSIONS--The cost based weightings proposed are believed to reflect the present distribution of prescribing costs, in relation to age and sex, in English general practice. They are intended for use in analyses at practice level.  相似文献   

8.
The medical costs for a type 2 diabetes patient are two to four times greater than the costs for a patient without diabetes. Bariatric surgery is the most effective weight‐loss therapy and has marked therapeutic effects on diabetes. We estimate the economic effect of the clinical benefits of bariatric surgery for diabetes patients with BMI ≥35 kg/m2. Using an administrative claims database of privately insured patients covering 8.5 million lives 1999–2007, we identify obese patients with diabetes, aged 18–65 years, who were treated with bariatric surgery identified using Healthcare Common Procedure Coding System codes. These patients were matched with nonsurgery control patients on demographic factors, comorbidities, and health‐care costs. The overall return on investment (RoI) associated with bariatric surgery was calculated using multivariate analysis. Surgery and control patients were compared postindex with respect to diagnostic claims for diabetes, diabetes medication claims, and adjusted diabetes medication and supply costs. Surgery costs were fully recovered after 26 months for laparoscopic surgery. At month 6, 28% of surgery patients had a diabetes diagnosis, compared to 74% of control patients (P < 0.001). Among preindex insulin users, insulin use dropped to 43% by month 3 for surgery patients, vs. 84% for controls (P < 0.001). By month 1, medication and supply costs were significantly lower for surgery patients (P < 0.001). The therapeutic benefits of bariatric surgery on diabetes translate into considerable economic benefits. These data suggest that surgical therapy is clinically more effective and ultimately less expensive than standard therapy for diabetes patients with BMI ≥35 kg/m2.  相似文献   

9.
Decision makers are interested in measuring the costs and benefits of various interventions, and sometimes they are presented with the average costs and benefits of alternative interventions and asked to compare these. Usually a newer intervention is being compared with an existing one, and the most appropriate comparison is not of average costs (and benefits) but of the extra--or marginal--costs (and benefits) of the new intervention. Reanalysis of the cost effectiveness ratio of biochemical screening of all women for Down''s syndrome compared with age based screening shows that the marginal cost effectiveness of biochemical screening is 47,786 pounds, compared with an average cost effectiveness of 37,591 pounds. It may sometimes be difficult or costly to calculate marginal costs and benefits, but this should be done whenever possible.  相似文献   

10.
Women attending a family planning clinic were studied to determine the relation between cervical erosion and clinical and social characteristics. The appearance of the cervix was recorded without knowledge of the women''s symptoms. The prevalence of erosion increased with parity but, when the effects of other factors were controlled, decreased in women aged 35 and over. Erosion was significantly more common in women taking the "pill" and less common in women using barrier methods of contraception than in others. There was considerable variation between doctors in the reporting of erosion. No association was found between erosion and postcoital bleeding, dyspareunia, backache, or dysuria. There was a significant but modest association between erosion and vaginal discharge and a suggestion that erosion may sometimes be associated with nocturia and frequency of micturition. Vaginal flora was similar in women with and without erosion. Cervical erosion should not be regarded as pathological in asymptomatic women, nor should it be assumed necessarily to be the cause of symptoms in women with genitourinary complaints.  相似文献   

11.
Because women's preferences for male masculinity reflect tradeoffs between the benefits of greater genetic health and the costs of lower paternal investment, variables that affect the importance of these costs and benefits also affect masculinity preferences. Concern about disease and pathogens may be one such variable. Here we show that disgust sensitivity in the pathogen domain is positively correlated with facial masculinity preferences, but disgust sensitivity in the moral and sexual domains is not. Our findings present novel evidence that systematic variation in women's preferences for masculine men reflects factors that influence how women resolve the tradeoff between the benefits and costs associated with choosing a masculine partner.  相似文献   

12.

Background  

Women have been able to delay childbearing since effective contraception became available in the 1960s. However, fertility decreases with increasing maternal age. A slow but steady decrease in fertility is observed in women aged between 30 and 35 years, which is followed by an accelerated decline among women aged over 35 years. A combination of delayed childbearing and reduced fecundity with increasing age has resulted in an increased number and proportion of women of greater than or equal to 35 years of age seeking assisted reproductive technology (ART) treatment.  相似文献   

13.
OBJECTIVE--To assess attendance at and the characteristics of patients attending health checks for cardiovascular disease offered in a general practice over a period of five years (1984-9). DESIGN--Medical record audit and postal questionnaire survey. SETTING--One general practice in Oxfordshire with a socially diverse population. PARTICIPANTS--1101 Men and 1110 women aged 35-64 registered with the practice. MAIN OUTCOME MEASURES--Age, sex, marital state, social class, smoking habits, alcohol consumption, and diet. RESULTS--Of the 2211 men and women in the target age group (35-64) in 1989, 1458 (65.9%) had been offered screening and 963 (43.6%) had attended for a health check. Attenders were more likely to be women, aged greater than or equal to 45, married, non-smokers, and of higher social class than patients who did not respond to the invitation. The relative likelihood of non-attendance was 1.24 for smokers, 1.20 for the overweight, 1.16 for heavy drinkers, and 1.28 for those with a less healthy diet, even after adjustment for age, sex, marital state, and social class. CONCLUSIONS--After five years of offering health checks, opportunistically (to men) and in the context of cervical smear tests (to women), less than half of the eligible patients had attended. The likelihood of acceptance of an invitation to attend was inversely related to the patient''s cardiovascular risk for all factors measured except age. A coherent strategy to reduce cardiovascular disease depends on more careful targeting of scarce health service resources and more emphasis on public health measures (such as dietary regulation and tobacco taxation). Doctors should be careful not to absolve the government of its public health obligations by substituting unproved preventive interventions aimed at the individual patient.  相似文献   

14.
To determine whether a cervical screening call system based in general practice in a deprived inner city area would increase the numbers of women who came forward for cervical smears the response to letters of invitation for screening was monitored for one year in one general practice in the Paddington and North Kensington district of London. Women aged 20-64 were identified from the computerised age-sex register. Only 16% of these women had had a smear test. A total of 750 call letters was sent out. Initially the response was poor (57 women; 22%), and 85 (32%) letters were returned marked "address unknown." After the age-sex register was updated the response to call was 330 women (44%). The response of women aged over 35 was better than the response of women aged 35 and under (229 (53%) v 101 (32%)). In the year of the study the number of women aged 20-64 on the revised register who had been screened rose by 330 (14%). A general practice based call system can improve uptake of cervical screening even in a highly mobile, socially underprivileged population.  相似文献   

15.

Objective

The number of women aged 45 and older who become pregnant is increasing. The objective of this study was to estimate the risk of medical and obstetric complications among women aged 45 and older.

Methods

The Nationwide Inpatient Sample was used to identify pregnant woman during admission for delivery. Deliveries were identified using International Classification of Diseases, Ninth Revision (ICD-9-CM) codes. Using ICD-9-CM codes, pre-existing medical conditions and medical and obstetric complications were identified in women at the time of delivery and were compared for women aged 45 years and older to women under age 35. Outcomes among women aged 35–44 were also compared to women under age 35 to determine if women in this group demonstrated intermediate risk between the older and younger groups. Logistic regression analyses were used to calculate odds ratios with 95% confidence intervals for pre-existing medical conditions and medical and obstetric complications for both older groups relative to women under 35. Multivariable logistic regression analyses were also developed for outcomes at delivery among older women, while controlling for pre-existing medical conditions, multiple gestation, and insurance status, to determine the effect of age on the studied outcomes.

Results

Women aged 45 and older had higher adjusted odds for death, transfusion, myocardial infarction/ischemia, cardiac arrest, acute heart failure, pulmonary embolism, deep vein thrombosis, acute renal failure, cesarean delivery, gestational diabetes, fetal demise, fetal chromosomal anomaly, and placenta previa compared to women under 35.

Conclusion

Pregnant women aged 45 and older experience significantly more medical and obstetric complications and are more likely to die at the time of a delivery than women under age 35, though the absolute risks are low and these events are rare. Further research is needed to determine what associated factors among pregnant women aged 45 and older may contribute to these findings.  相似文献   

16.
OBJECTIVE--To determine whether there is sufficient benefit to be gained by offering screening for breast cancer with mammography to women aged 65-79, who are not normally invited for screening. DESIGN--Pilot study of women eligible for screening but not for personal invitation. The results of this study were compared with the results of routinely screened younger women (aged 50-64) from the same general practice. SETTING--One group general practice in south Manchester. PATIENTS--The 631 women aged 65-79 on the practice list. A total of 42 (7%) were excluded by the general practitioner, and 22 (4%) invitation letters were returned by the post office. MAIN OUTCOME MEASURES--Response rates to invitation for screening assessed by three indices: crude population coverage ratio, crude invited population coverage ratio, and corrected invited population coverage ratio. RESULTS--344 Patients aged 65-79 (61% of those invited, excluding those who could not be traced) were screened compared with 77% of women aged 50-64. The three response indices were higher for younger women than older: crude population coverage ratio = 66.5%, crude invited population coverage ratio = 69.3%, corrected invited population coverage ratio = 76.8% for women aged 50-64, compared with 54.5%, 58.4%, and 60.7% respectively for women aged 65-79. All four biopsies done in the older women gave positive results, giving a cancer detection rate of 11.6/1000 compared with 4.1/1000 among younger women. CONCLUSIONS--These results show that there is a potential for high attendance at routine screening by older women if they are invited in the same way as younger women. If these results are found elsewhere the costs and benefits of screening older women should be reassessed.  相似文献   

17.
The prevalence of use of oral contraception before the onset of disease was established in 100 consecutive women attending follow up clinics for inflammatory bowel disease. A significant excess of women with Crohn''s disease confined to the colon had taken oral contraceptives in the year before developing symptoms (10/16 (63%] compared with women with small-intestinal Crohn''s disease (12/49 (24%); p less than 0.02) and women with ulcerative colitis (3/35 (9%); p less than 0.0005). When the patient groups were matched for age and year of onset of disease usage of oral contraception before the onset of disease was still more common among women with isolated colonic Crohn''s disease (9/12, 75%) than among those with ulcerative colitis (2/12 (17%); p less than 0.02) and was also more common than would be expected from reported figures for oral contraception in England and Wales (31.4% of women aged under 41; p less than 0.005). A survey of current patient records showed that isolated colonic disease was at least twice as common among women with Crohn''s disease (63/218, 29%) compared with men (25/181, 14%; p less than 0.001). These data support the suggestion made previously that oral contraceptives may predispose to a colitis that resembles colonic Crohn''s disease.  相似文献   

18.
ObjectiveTo estimate the relation between alcohol consumption and risk of death, the level of alcohol consumption at which risk is least, and how these vary with age and sex.DesignAnalysis using published systematic reviews and population data.SettingEngland and Wales in 1997.ResultsA direct dose-response relation exists between alcohol consumption and risk of death in women aged 16-54 and in men aged 16-34. At older ages the relation is U shaped. The level at which the risk is lowest increases with age, reaching 3 units a week in women aged over 65 and 8 units a week in men aged over 65. The level at which the risk is increased by 5% above this minimum is 8 units a week in women aged 16-24 and 5 units a week in men aged 16-24, increasing to 20 and 34 units a week in women and men aged over 65, respectively.ConclusionsSubstantially increased risks of all cause mortality can occur even in people drinking lower than recommended limits, and especially among younger people.

What is already known on this topic

Non-drinkers and heavy drinkers have higher all cause mortality rates than light drinkers—the U shaped curveThe precise shape and location of the U are likely to depend on age and sex, but this has not been quantified

What this study adds

The level of alcohol consumption that carries the lowest mortality ranges from 0 in men and women aged under 35 to 3 units a week in women aged over 65 and 8 units a week in men aged over 65The level of alcohol consumption that carries a 5% increase in mortality increases with age from 8 to 20 units a week in women and from 5 to 34 units a week in menOur calculations were for England and Wales in 1997: nadirs are likely to be lower in the future and in countries with less ischaemic heart disease  相似文献   

19.
The number of cases of intraepithelial carcinoma of the cervix among women of different age groups has been related to the number of cervical smears from women of the same age groups. Among women aged 25 to 34 years the incidence of intraepithelial carcinoma was 0·67% and among those aged 35 to 44 years it was 0·75%. The overall rate of intraepithelial carcinoma in women under 35 years was 0·55% compared with an overall rate of 0·59% in women over 35 years.If screening of women for cervical cancer is to play any part in preventive medicine it is suggested that the national campaign for the early detection of cervical cancer should be expanded to encourage practitioners to take cervical smears from younger women, particularly from those under 35 years.  相似文献   

20.
The goal of this study was to assess the consequences of single versus multiple paternity by identifying paternity of clutches per female to identify whether there were detectable costs or benefits. Multiple mating can occur when the benefits of mating outweigh the costs, but if costs and benefits are equal, no pattern is expected. Previous research on loggerhead sea turtle (Caretta caretta) populations found male‐biased breeding sex ratios and multiple mating by many females nesting in southwestern Florida. A sample of nesting loggerhead females who laid more than one nest over the course of the season and a subset of their hatchlings were examined from 36 clutches in 2016 on Sanibel Island, Florida. Males that fathered hatchlings in the first clutch sampled were identified in subsequent clutches. Interestingly, 75% of the females analyzed had mated singly. No male was represented in more than one female's clutches. The results suggest that females likely mate at the beginning of the season and use stored sperm for multiple clutches. Evidence for mating between laying events was limited. There was no consistent pattern across the subsequent multiple paternity clutches, suggesting benefits to loggerhead females likely equal their costs and subsequent mating is likely determined by female preference.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号