Natural fertility in northeastern Mexico

BACKGROUND: The aims of this study were as follows: 1) to describe the fertility of a sample of Mexican women (> or =45 years of age, married, not using any family planning methods, and residing in the Mexican state of Nuevo León); 2) to determine whether or not the distribution of completed family size fits the negative binomial distribution, as in other populations studied in the world, and 3) to assess the association between fertility and 10 explanatory variables. METHODS: A sample of 410 women was interviewed at and selected from seven medical units of the Instituto Mexicano del Seguro Social (IMSS). The women were grouped by their year of birth (1896-1925 and 1926-1955) and birthplace [persons whose four grandparents were born in northeastern Mexico (NE) and outside northeastern Mexico (Not-NE)]. A binomial negative distribution analysis was assessed. Multiple linear regression was used to assess association between fertility (transformed by the use of inverse hyperbolic sines) and 10 explanatory variables, including age at marriage, heterozygosity, individual admixture, wife's education, husband's education, wife's occupation, husband's occupation, and couple's residence zone, birth year, and birthplace. RESULTS: Completed fertility was only associated with age at marriage. This population showed a fertility pattern similar to those described in Venezuelan and Brazilian populations in 1950 and 1940, respectively. CONCLUSIONS: We conclude that before worldwide family planning programs, fertility was determined mainly by natural selection forces.     

Male fertility in Crohn's disease

The fertility of 70 men with Crohn's disease and a group of age matched controls were compared. Crohn's disease was associated with a significant reduction in family size independent of steroid or sulphasalazine treatment.     

Recent observations on drugs and human fertility

The transmembrane migration method has permitted quantification of the effect of drugs on human sperm motility. Calcium ionophores and calcium antagonists have paradoxical effects on motility depending on the stage of sperm maturity. Drugs with membrane stabilizing properties inhibit sperm motility. Propranolol, for example, has been shown to have contraceptive activity when administered intra-vaginally. Pharmacokinetic studies have shown that the systemic availability of vaginally administered propranolol is markedly greater than after oral administration. Seminal fluid concentrations of propranolol after oral administration are similar to those in plasma, but cervicovaginal mucus concentrations are much higher, and residence times much longer. The clinical consequences of these observations await elucidation.     

生育力保存的伦理问题及思考

生育力保存技术是一项新兴的技术,近年来逐渐成熟,由实验走向临床应用。它一方面满足了人们日益增长的生育力保存的需求,另一方面在技术实施过程中不可避免会面临巨大伦理困境。临床诊疗实践中要坚持尊重、有利、公平的伦理原则,在此基础上发展科学技术、优化医疗资源配置、完善法规政策、加强伦理监管和技术评审等,或许可以为解决伦理难题提供参考和方法。     

Malnutrition, fertility and family planning.

Data derived primarily from published reports is used to assess the relationship between malnutrition and reproductive capacity in India. Findings of numerous studies support the conclusion that improvements in nutritional status are associated with increased fertility in the absence of contraception. Nutritional programs should therefore be provided in conjunction with family planning services in order to avoid an increase in population growth. Improvements in the nutritional status of members of a community may help motivate the community toward family planning. A recent Indian study demonstrates that higher caloric intake is associated with smaller family size, and other studies reveal a relationship between malnutrition and pregnancy failure, stillbirth, and infant mortality. The high infant mortality rate in India at the present time may serve to increase family size since couples tend to over produce in order to insure that some of their children will survive. The hypothesis that an inadequate diet is compensated for by an increase in sexual appetite, and hence, in fertility is not substantiated by recent investigations. For example, Indian states with higher protein intake/person have higher birth rates than those states with lower protein intake/person. Tables provide data on 1) birth rates, death rates, infant mortality rates, % of population increase, and sex ratios for each decade from 1921-1970 for India; 2) the relationship between diet and birth rates in several countries; 3) the relationship between various dietary factors and birth, death, and infant mortality rates forIndia; 4) fertility rates observed in several populations where contraception was not practiced; and 5) the relationship between family size and diet in India.     

Preserving the fertility of children with cancer

Moving beyond the uncertainties of risk, and limited, often difficult, preservation options, will require consensus and collaborative research.     

女性生育力保护的现状与进展

生育力保护是一个新兴的、快速发展的跨学科领域。近年该领域研究取得了巨大进展,生育力保护新技术得到了广泛应用。实施生育力保护是保留生育能力和解决不孕问题的重要环节,首先,能保护患者的生育能力免受疾病或环境因素损伤,如年轻肿瘤患者卵子或卵巢组织的体外冷冻保存;其次,以生育为主要目的的手术,解决部分不孕患者的病因,修复或重建生殖器官的结构与功能;最后,作为辅助生殖措施的补充治疗,可以提高辅助生殖的成功率。本文着重强调生育力保护方面的主要发展,指出这一新的研究领域仍然面临的挑战,并就中国生育力保护的发展提出建议。     

环境因素对男性生育力的影响

随着科学技术的进步和工业化的发展,环境污染严重影响生殖系统功能,男性生殖健康日益受到人们的重视。了解环境因素对精子发生的毒性作用,为临床治疗提供理论依据。