The aim of this study was to investigate a seasonal pattern of preterm births in Korea. Data were obtained from the national birth registry of the Korean Statistics Office and included all births in Korea during the period 2000-2012 (n = 6,310,800). Delivery dates were grouped by month of the year or by season (winter [December, January, February], spring [March, April, May], summer [June, July...

OBJECTIVE To examine the trends in the proportion of annual live births that were male in Canada and to compare the trends with those in the United States. DESIGN Analysis of census data. SETTING Canada as a whole and 4 main regions (West, Ontario, Quebec and Atlantic). SUBJECTS All live births from 1930 to 1990. OUTCOME MEASURES Sex ratio (expressed as the proportion of total live birt...

OBJECTIVE To compare the effects on pregnancy outcomes of changing partner between the first two births with having the same partner for both births. DESIGN Prospective population study. SETTING Norway. PARTICIPANTS 31 683 women who changed partner between their first two births and 456 458 women with the same partner for both births. RESULTS After adjustment for maternal age and educat...

background and purpose: prematurity birth occurs when a newborn is born before the thirty seventh week of pregnancy. preterm birth is the most expensive and the most common health problem. so, the aim of this study was to do epidemiological survey of prematurity in gonbad-e kavous in 2010. materials and methods: this sectional- descriptive study was carried out on 172 premature babies with cens...

The aim of this paper was to investigate seasonal fluctuations of the number of births in Croatia. Vital registration data from the years 1970-2002 was used for analysis of the quarterly data (from the years 1970-1997), and monthly data (from the years 1998-2002). Both data sets were smoothed, using seasonal variation removal for quarterly data, and T4253H smoothing for monthly data. Edwards te...

On the basis of MEDLINE and manual searches, we examined the main papers in the English literature regarding risk factors for spontaneous (i.e. not related to fertility drug use) multiple births. The constant frequency of monozygotic (MZ) pregnancies over time and in different geographical areas suggests that the determination of MZ twins is largely unchanged over time, and that a genetic mecha...