BACKGROUNDInfertility is one of the most important and underappreciated reproductive health problems in developing countries. However, epidemiological data in the Chinese population are still sparse. The aim of the present study was to determine the current prevalence and prevalence trend of infertility in Beijing, and to identify the risk factors associated with infertility.

METHODSThis cross-sectional study was conducted in Beijing in 2012. A stratified cluster sampling method was used to select 12 448 couples of whom the female partners were born between 1955 and 1985. All subjects were interviewed face to face. Infertility was defined as the failure to achieve a clinical pregnancy after 12 months of regular unprotected sexual intercourse.

RESULTSOf the 12 448 couples, 12 342 (99.1%) answered the questions appropriately. The prevalence of infertility was 4.2% (3.1% as primary and 1.1% as secondary infertility). An increase in the prevalence of infertility according to the age of the female partner was found: 1.3% infertility for married females born in the 1950s and 11.4% for married females born in the 1980s. The increase was found in both urban and suburban areas. In addition, a Logistic regression showed that for the female partner, higher education levels, an older age at first marriage, adverse occupational conditions, mental labor and pre-pregnancy contraception after marriage were all significantly associated with a higher risk of infertility.

CONCLUSIONThe prevalence of infertility has increased significantly among couples in Beijing, possibly because of an interaction among multiple factors.

Adult ; China ; epidemiology ; Cross-Sectional Studies ; Female ; Humans ; Infertility ; epidemiology ; Male ; Middle Aged ; Prevalence ; Risk Factors

To begin with, we constructed cfp10-esat6 fusion gene and its prokaryotic expression vector and had it express in E. coli. By GeneSOEing techniques, a fusion gene was constructed by splicing cfpl0 gene and esat6 gene, and then was cloned into pGEX-4T-1 plasmid. Secondly, we constructed the prokaryotic expression recombinant plasmid pGcfp10-esat6. After identification with restriction enzyme analysis, PCR and nucleotide sequencing analysis, The E. coli BL21 containing the recombinant plasmid was induced by IPTG (Isopropy-beta-D-thiogalatoside). The fusion protein CFP10-ESAT6 with GST-tag about 42 kDa was expressed and purified with GST-fusion protein purification kit,The expression of cfp10-esat6 fusion gene was subsequently detected by SDS-polyacrylamine gel electrophoresis and Western-blot analysis. The sequence of cfp10 and esat6 in recombinant plasmid was consistent with that of GenBank report. The fusion protein existed in cytoplasm in soluble form and represented about 40% total bacterial protein of E. coil. The fusion protein was purified and the purity reached 90%. Its antigenicity was confirmed by Western-blotting. The prokaryotic expression vector (pGcfp1o-esat6) was constructed successfully, and the fusion protein CFP10-ESAT6 was obtained. This study provided an experimental basis for potential application of the recombinant CFP10-ESAT6 in the diagnosis of tuberculosis.
Antigens, Bacterial ; biosynthesis ; genetics ; Bacterial Proteins ; biosynthesis ; genetics ; Cloning, Molecular ; Escherichia coli ; genetics ; metabolism ; Mycobacterium tuberculosis ; genetics ; Recombinant Fusion Proteins ; biosynthesis ; genetics ; isolation & purification