Determinants Of Female Fertility Research Articles

Dynamics Of Female Fertility In Indonesia, Thailand And The Philippines, 1980-2014

ASEAN-3 countries displayed a high fertility rate and infant mortality rate in the beginning of the formation of ASEAN in 1967, but towards the end of the 20th century and the beginning of the 21st century, there is a reversal of this pattern. Literature review on the determinants of female fertility reveals the importance of infant mortality, income, female secondary education, female employment and age dependency as key determinants of female fertility. This study, therefore, attempts to identify the determinants of female fertility for the ASEAN-3 countries, namely Indonesia, Thailand and the Philippines. Firstly, using the Johansen cointegration method, we identified the presence of a long-run relationship between female fertility rate, infant mortality, income, female secondary education, female employment and age dependency ratio for all three countries. Secondly, we identified three major determinants of female fertility for Indonesia as female education, age dependency ratio and infant mortality which is in line with the theory. For Thailand, two main determinants of female fertility include female education and income. For the Philippines, two important variables that determine female fertility are female employment and infant mortality. Finally, we found a deviation of fertility rate from the short-run to the long-run equilibrium for those three countries, with the highest and lowest speed of adjustment recorded for the Philippines and Indonesia, respectively. Keywords: female fertility, secondary education, female employment, age dependency ratio, cointegration

DETERMINANTS OF FEMALE FERTILITY IN ASEAN-5: EMPIRICAL EVIDENCE FROM BOUNDS COINTEGRATION TEST

The ASEAN countries have been experiencing drastic declines in fertility of more than 10 percent, particularly since the 1990s. Though the literature on fertility has clearly delineated the importance of income, female labor force participation and infant mortality as key determinants of fertility rates (FRs), the empirical findings from previous studies remains at best mixed. This study therefore identifies the determinants of female fertility for the countries, namely Indonesia, Malaysia, Philippines, Singapore and Thailand (ASEAN-5 countries), spanning the period 1980–2010. Using the Autoregressive Distributed Lag (ARDL) cointegration and causality techniques, the main findings of the study are summarized as follows: First, a long-run (LR) stable relationship is evident between female fertility, female labor force participation, income and infant mortality for ASEAN-5. Second, there is a deviation of FRs from the short-run (SR) to the LR equilibrium for ASEAN-5, with the highest and lowest speed of adjustment recorded for Malaysia and Thailand, respectively. Third, FR and economic stability are found to be complementary in the LR for ASEAN-5. When the joint LR and SR causalities are considered, we found that female labor force participation, income and infant mortality have dynamic relationships with FR for all the five ASEAN countries.

Down-regulation of the liver-derived plasma protein fetuin-B mediates reversible female infertility

Does antisense oligonucleotide (ASO)-mediated down-regulation of serum fetuin-B cause infertility like fetuin-B gene deficiency in female mice? Pharmacological fetuin-B down-regulation by ASO therapy results in reversible infertility in female mice. Female fetuin-B deficient (Fetub-/-) mice are infertile owing to premature zona pellucida (ZP) hardening. Enzyme activity studies demonstrated that fetuin-B is a potent and highly specific inhibitor of the zona proteinase ovastacin, which cleaves ZP protein 2 (ZP2) and thus mediates definitive ZP hardening. Ten fetuin-B ASO boli (100 mg/kg) were injected s.c. over 20 days in 12 female mice, and 10 phosphate-buffered saline (PBS)-treated mice were used as control. At day 20 females were mated to evaluate fetuin-B as a potential molecular target for contraception. ASO and PBS treatment was continued for ten injections. After treatment cessation at day 50, mating was continued to investigate if infertility was reversible. We generated fetuin-B/ovastacin double deficient (Fetub-/-, Astl-/-) mice by conventional breeding to test if fertility of Fetub-/- female mice was restored when the target proteinase would likewise be deleted. At least five matings with each female genotype (Fetub-/- single deficient, Astl-/- single deficient, Fetub-/-, Astl-/- double deficient) were performed. To test the contraceptive effect of fetuin-B down-regulation, 22 female mice (6-13 weeks old) were treated with repetitive boli of 100 mg/kg fetuin-B ASO (n=12) or PBS (n=10) and mated continuously. Serum fetuin-B was determined by immunoblot before, during and after the ASO treatment. After 3 weeks of ASO treatment, in 6 females Fetub mRNA in liver was analyzed by PCR, and six PBS-treated females were used as control. Aspartate (AST) and alanine aminotransferase (ALT) were also measured in serum of six mice in each group. To determine the minimum permissive serum fetuin-B concentration required for successful fertilization IVF was performed in five fetuin-B ASO-treated mice. As a control, six females were injected with control oligonucleotides and six females were left untreated. Fertility of Fetub-/- female mice was restored by additional ovastacin deficiency (Astl-/-). Unlike Fetub-/- mice, female Fetub-/-, Astl-/- mice were fertile, confirming ovastacin as a primary molecular target of fetuin-B. At day 20, after receiving 10 fetuin-B ASO boli, serum fetuin-B was down-regulated to 8±6% (mean ± SD) of baseline level. Fetuin-B down-regulation was confirmed at the mRNA level. Fetuin-B ASO-treated females had 12.1±3.1% of the liver Fetub mRNA level seen in PBS-treated females. In the following mating study, 11 out of 12 mated females failed to become pregnant during 50 days of ASO treatment and continuous mating from day 20 onwards. IVF of oocytes derived from ASO-treated females suggested that a serum fetuin-B level of less than 10 µg/ml was required to prevent pregnancy. Withdrawal of ASO treatment normalized serum fetuin-B and restored fertility; all female mice became pregnant and had litters within 60.3±35.9 days after cessation of ASO treatment. The first litter was significantly smaller than that of control mice (4.6±2.3 versus 6.7±1.8 pups, n=20, P=0.04) but the smaller litter size was only temporary. The size of the second litter was similar to the first litter of control mice (7.6±1.3 versus 6.7±1.8 pups, n=18, P=0.25). The repeated dose of 100 mg/kg fetuin-B ASO boli caused an increased serum ALT and AST activity, suggesting hepatotoxicity. Daily vaginal plug checks indicated successful mating, but mating plugs in ASO-treated mice were less stable (vaginal tract not closed) than in control mice. Pharmacological fetuin-B down-regulation in mice caused reversible infertility. Control of ovastacin proteinase activity by fetuin-B is a necessary determinant of female fertility that can serve as a target for female contraception. Although promising in terms of human contraception, further studies analyzing the balance between sufficient fetuin-B down-regulation and tolerable side effects are required to improve safety before transfer into human reproductive biology can be considered. None. The research was supported by a grant from Deutsche Forschungsgemeinschaft and by the START program of the Medical Faculty of RWTH Aachen University. The authors E.D., J.F. and W.J.-D. are named inventors on a patent application of RWTH Aachen University covering the use of fetuin-B in ovary and oocyte culture. No conflict of interest is declared by C.S. and A.C.

The gametic synapse: RNA transfer to the bovine oocyte.

Even after several decades of quiescent storage in the ovary, the female germ cell is capable of reinitiating transcription to build the reserves that are essential to support early embryonic development. In the current model of mammalian oogenesis, there exists bilateral communication between the gamete and the surrounding cells that is limited to paracrine signaling and direct transfer of small molecules via gap junctions existing at the end of the somatic cells' projections that are in contact with the oolemma. The purpose of this work was to explore the role of cumulus cell projections as a means of conductance of large molecules, including RNA, to the mammalian oocyte. By studying nascent RNA with confocal and transmission electron microscopy in combination with transcript detection, we show that the somatic cells surrounding the fully grown bovine oocyte contribute to the maternal reserves by actively transferring large cargo, including mRNA and long noncoding RNA. This occurrence was further demonstrated by the reconstruction of cumulus-oocyte complexes with transfected cumulus cells transferring a synthetic transcript. We propose selective transfer of transcripts occurs, the delivery of which is supported by a remarkable synapselike vesicular trafficking connection between the cumulus cells and the gamete. This unexpected exogenous contribution to the maternal stores offers a new perspective on the determinants of female fertility.

Determinants of Female Fertility in Taiwan, 1966–2001: Empirical Evidence from Cointegration and Variance Decomposition Analysis*

This study investigates the determinants of the fertility rate in Taiwan over the period 1966–2001. Consistent with theory, the key explanatory variables in Taiwan's fertility model are real income, infant mortality rate, female education and female labor force participation rate. The test for cointegration is based on the recently developed bounds testing procedure while the long‐run and short‐run elasticities are based on the autoregressive distributed lag model. Among our key results, female education and female labor force participation rate are found to be the key determinants of fertility in Taiwan in the long run. The variance decom‐position analysis indicates that in the long run approximately 45percent of the variation in fertility is explained by the combined impact of female labor force participation, mortality and income, implying that socioeconomic development played an important role in the fertility transition in Taiwan. This result is consistent with the traditional structural hypothesis.