The views expressed herein are those of the authors and not necessarily those of the National Bureau of Economic Research. ABSTRACT Recent research into the implications of low birth weight may be plagued by unobserved variable bias. It is unclear whether the later-life consequences found to be associated with low birth weight are a true effect of " poundage " at birth, or whether this associat...

BACKGROUND Necrotizing Enterocolitis (NEC) is the most common gastrointestinal emergency in neonates. Previously established risk factors for the development of NEC include prematurity and low birth weight. However, it is not clear to date as to whether the etiology of NEC is due to host, environmental, or yet other unknown factors. We analyzed the differences in incidence of NEC in twin pregna...

OBJECTIVE The purpose of this study was to evaluate combined fetal fibronectin (fFN) test result and cervical length (CL) as predictors of spontaneous preterm birth in asymptomatic twin pregnancies. STUDY DESIGN We examined a retrospective cohort of 155 twin pregnancies with combined fFN and CL testing between 22 and 32 weeks gestation. RESULTS A positive fFN test result at 22-32 weeks or a...

Norway has a long-standing tradition in twin research, but the data collected in several population-based twin studies were not coordinated centrally or easily accessible to the scientific community. In 2009, the Norwegian Twin Registry was established at the Norwegian Institute of Public Health (NIPH) in Oslo with the purpose of creating a single research resource for Norwegian twin data. As o...

OBJECTIVES To evaluate the effect of cervical cerclage on preventing preterm birth in twin pregnancies. METHODS We searched Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, Current Controlled Trials, China Biology Medicine (CBM), Chinese National Knowlegde Infrastructure (CNKI) and VIP Chinese Journal database (VIP) from April to August 2012. All available randomized...

PURPOSE To compare the distributional parameters for a series of ocular biometric traits between twins and their singleton siblings, to evaluate the generalizability of twin data, as used in heritability analyses to the general population. METHODS A series of birth, anthropometric, and 13 ocular biometric traits were selected for analysis: interpupillary distance (IPD), visual acuity (logMAR)...

Aim. To study the impact of birth characteristics on the risk of atopic dermatitis in a twin population. Methods. In a population-based questionnaire study of 10,809 twins, 3-9 years of age, from the Danish Twin Registry, we identified 907 twin pairs discordant for parent-reported atopic dermatitis. We cross-linked with data from the Danish National Birth Registry and performed cotwin control a...