purpose: to determine the frequency and severity of retinopathy of prematurity (rop) among singleton and multiple-birth neonates referred to farabi eye hospital, tehran-iran. methods: we reviewed the records of 99 consecutive neonates from multiple-gestation pregnancies including 68 twins, 26 triplets and 5 quadruplets who were screened for rop during 2002-2004. the frequency, severity and risk...

Little research has investigated whether the twin representativeness assumption (that results from twin research generalize to singletons) holds for eating pathology and internalizing symptoms. This study compared disordered eating, depression, and anxiety among young adult female twins versus singletons. Participants included 292 twins and 997 singletons in three samples. Questionnaires includ...

Studies have reported that refractive errors are associated with premature births. As twins have higher prevalence of prematurity than singletons, it is important to assess similarity of the prevalence of refractive errors in twins and singletons for proper interpretations and generalizations of the findings from twin studies. We compared refractive errors and diopter hours between 561 pairs of...

BACKGROUND There is increasing use of cryopreservation in IVF. This study compared singletons born after cryopreservation with singletons born after fresh IVF cycles and singletons born to women in the general population. METHODS Data were collected for Swedish IVF treatments during the years 2002-2006. All singletons from single embryo transfer (SET) and double embryo transfer (DET) after cr...

To investigate whether salient visual singletons capture attention when they appear outside the current endogenous attentional focus, we measured the N2pc component as a marker of attentional capture in a visual search task where target or nontarget singletons were presented at locations previously cued as task-relevant, or in the uncued irrelevant hemifield. In two experiments, targets were ei...

Objective: To compare the infant mortality rate (IMR) due to sudden infant death syndrome (SIDS) in twins and singletons and consider the risk factors of SIDS. Materials and methods: The IMR due to SIDS was analyzed among twins and singletons from 1995 to 2008 using the Japanese Vital Statistics. Results and discussion: The IMR for both twins and singletons decreased (1/3-1/4) significantly dur...

In the present study, we tested whether visual singletons remaining outside awareness are processed. Singletons differ by at least one feature from their more homogeneous neighbors. Here, we used backward masking to prevent awareness of shape singleton primes (Experiments 1-4) or color singleton primes (Experiment 5). Masked singleton primes nonetheless produced a congruence effect: Congruent s...

This study analyzes grouping between singletons (line elements popping out by orientation gradient) when they segregate from textures of uniformly oriented line elements. In the first experiment three adjacent singletons formed a texture bar; in the second experiment the distance between two singletons to be grouped was manipulated. The observer's task was to discriminate the orientation of the...

STUDY QUESTION Among babies born by ART, do singleton survivors of a vanishing twin have lower birth weight than other singletons? SUMMARY ANSWER Vanishing twin syndrome (VTS) was associated with lower birth weight among ART singletons; a sibship analysis indicated that the association was not confounded by maternal characteristics that remain stable between deliveries. WHAT IS KNOWN ALREAD...