Fertility

About: Fertility is a research topic. Over the lifetime, 29988 publications have been published within this topic receiving 681106 citations.

Sperm Mobility: A Primary Determinant of Fertility in the Domestic Fowl (Gallus domesticus)

Abstract: Previous research demonstrated that sperm mobility is a quantitative trait of the domestic fowl. The trait is quantified by measuring the absorbance of an Accudenz solution after overlay with a sperm suspension and brief incubation at body temperature. In the present work, average and high sperm mobility phenotypes (n = 30 males per phenotype) were selected from a base population. Differences were found between sperm oxygen consumption (p < 0.0001), acylcarnitine content (p < 0.05), linear velocity (p < 0.001), and straightness (p < 0.001), a trajectory variable measured with the Hobson SpermTracker. Oxygen consumption and stearoylcarnitine content of sperm from the high-mobility phenotype were twice those observed with sperm from average males, implying a pivotal role for mitochondria. On the basis of these results, a graded relationship was predicted between fertility and sperm mobility. Males (n = 48) were chosen at random from another base population, sperm mobility was measured per male, and each ejaculate was used to inseminate 8-12 hens (8 x 10(7) viable sperm per hen). When fertility was plotted as a function of sperm mobility, data points approximated a skewed logistic function. The hypothesis that vaginal immunoglobulins constitute an immunological barrier to sperm transport was tested and rejected. Therefore, we concluded that sperm mobility is a primary determinant of fertility in the fowl.

Pregnancies in women with Turner's syndrome.

Abstract: Ovarian failure is a typical feature in Turner's syndrome. Therefore, hormone replacement therapy (HRT) is necessary to achieve the development of normal female sexual characteristics and to prevent cardiovascular complications and osteoporosis. Spontaneous puberty occurs in 5-10% of women with Turner's syndrome, and 2-5% of them become pregnant spontaneously. Sexually active young women with Turner's syndrome need contraception. It can be administered as contraceptive pills, which also serve as HRT. Oocyte donation is now a treatment option for infertility of these women. Excellent results have been obtained with 46% of embryo transfers resulting in pregnancy. The pregnancies carry high risks and have to be followed up carefully. The children born following oocyte donation have no additional risks. Risks can be reduced by transferring only one embryo at a time to the uterus, thus avoiding twin pregnancies. Ovarian tissue from young girls with Turner's syndrome could be cryopreserved for infertility treatment in the future, but the optimal age of ovarian biopsy has to be studied, and methods of replantation and maturation of oocytes in vitro have still to be developed. Fertility counselling has become important in the treatment of girls with Turner's syndrome.

Public Policy as the Fuel of Fertility: Effects of a Policy Reform on the Pace of Childbearing in Sweden in the 1980s:

Abstract: In Sweden the total fertility rate (TFR) stopped declining in the late 1970s and started rising in the mid-1980s. The TFR exceeded the replacement level in 1990 and stayed above it in 1991. Characteristics of this recent fertility increase and the role of public policies are discussed. A technique called improved indirect standardization produced annual indexes of the level of childbearing at various birth orders. Swedish first-birth rates for single years of age for each calendar year from 1961 to 1990 were split into groups of ages. The rates al all ages below 30 generally fell from the mid-1960s through the early 1980s but there has been a mild recovery since 1984. At ages above 30 first-birth rates rose strongly in the 1980s as part of a steady postponement of the first birth to higher ages than before. About 82% of Swedish women who become mothers also had a second child and almost 40% of these also had a third child. Third-order birth rates increased up to the third year after the second birth and then declined steadily. The level of third and fourth birth rates fell from the mid-1960s to about 1977 and then recovered. The curves rose particularly strongly for mothers of children of age 1 with a further boost for this group starting about 1984. The strongly positive fertility gradient for age 1 of the youngest child and the corresponding break in 1986 for age 2 (but not age 2.5) may be a response to policy change. Recent fertility developments can be attributed to the muted pronatalism of social policies the growth of the day-care system and the extension of parental leave from 9 to 12 months. During the 1970s a premium on further childbearing was paid provided the interval between the 2 births did not exceed the period of statutory leave plus 6 months.

Population Policies, Fertility, Women's Human Capital, and Child Quality

Abstract: Population policies are defined here as voluntary programs which help people control their fertility and expect to improve their lives. There are few studies of the long-run effects of policy-induced changes in fertility on the welfare of women, such as policies that subsidize the diffusion and use of best practice birth control technologies. Evaluation of the consequences of such family planning programs almost never assess their long-run consequences, such as on labor supply, savings, or investment in the human capital of children, although they occasionally estimate the short-run association with the adoption of contraception or age-specific fertility. The dearth of long-run family planning experiments has led economists to consider instrumental variables as a substitute for policy interventions which not only determine variation in fertility but are arguably independent of the reproductive preferences of parents or unobserved constraints that might influence family life cycle behaviors. Using these instrumental variables to estimate the effect of this exogenous variation in fertility on family outcomes, economists discover these "cross effects" of fertility on family welfare outcomes tend to be substantially smaller in absolute magnitude than the OLS estimates of partial correlations referred to in the literature as evidence of the beneficial social externalities associated with the policies that reduce fertility. The paper summarizes critically the empirical literature on fertility and development and proposes an agenda for research on the topic.