منابع مشابه
Relative frequencies and sex distributions of human multiple births.
Hellin (1895) published evidence indicating that the relative frequencies of multiple births conform to a simple mathematical relationship which may be expressed thus: The frequency of triplet maternities is equal to the square of the frequency of twin maternities, and the frequency of quadruplet maternities is equal to its cube. Stated in general terms, if f is the frequency of twin litters, t...
متن کاملPerinatal problems in multiple births.
BACKGROUND Multiple pregnancies have become more common in the industrialized world because of rising maternal ages and advances in reproductive medicine. METHODS Selective literature review. RESULTS Multiple pregnancy carries a higher risk of prematurity, intrauterine growth restriction, and prenatal death, as well as elevated risks to the mother including preeclampsia, diabetes, and hemor...
متن کاملTehran Survey of Potential Risk Factors for Multiple Births
Background The incidence of multiple pregnancies has increasing worldwide and it is related to concern in the health care system. This study was aimed to determine the frequencyof multiple pregnancies, and to identify factors affecting the frequency of the phenomena in Tehran, Iran. MaterialsAndMethods In this cross sectional study, 5170 mothers in labor between July 6 to 21 2015 referred to 10...
متن کاملThe epidemiology of multiple births.
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...
متن کاملCerebral palsy and multiple births in China.
BACKGROUND A population-based study on prevalence of cerebral palsy in multiple births has not been carried out in China. The purpose of this paper was to determine the prevalence of cerebral palsy in multiple births and to explore the influence of multiple pregnancy on cerebral palsy after controlling for birthweight. METHODS A cross-sectional study of cerebral palsy was carried out among 38...
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ژورنال
عنوان ژورنال: Science
سال: 1914
ISSN: 0036-8075,1095-9203
DOI: 10.1126/science.39.1008.611