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This study was designed to reveal structural abnormalities in singleton and twin pregnancies in the Chinese population. This retrospective study spanned 8 years and included 1228 singleton pregnancies (112,919 examinees) and 49 twin pregnancies (1865 examinees) with structural anomalies diagnosed by ultrasound. Detailed descriptions of anomalies, gestational weeks at diagnosis, and maternal age were recorded. The odds ratio was evaluated in twin pregnancies with detectable structural anomalies. The annual average “ultrasound prevalence of fetal anomalies” among singleton and twin pregnancies were 1.09 and 3.06%, respectively. Mothers with twin anomalies were older (P< .001), and twin pregnancies were diagnosed with anomalies in earlier gestational weeks than singleton (P= .011). No differences were found in the types of anomalies between singleton and twin pregnancies. Central nervous system anomaly was the most common type in singleton and twin pregnancies. Twin pregnancies had higher rates of major anomalies than singleton (total OR 2.45), especially cardiovascular, central nervous, and gastrointestinal systems and ear/eye/face/neck disorders. Compared with singleton, twin pregnancies had higher odds of detectable structural anomalies. Twin pregnancies with structural anomalies were diagnosed at earlier gestational age and associated with older maternal age. Central nervous system anomaly was the most common type in singleton and twin pregnancies.

It is reported that the Goos–Hänchen (GH) shift of both TE and TM light beams totally reflected from a dielectric interface can be greatly enhanced by a dielectric thin film without changing the property of total internal reflection. Numerical simulations confirm the theoretical analysis and show that the enhanced GH shift can be as large as the width of the beam for beam's width up to 820 times of the wavelength. This may stimulate investigations in other areas of physics and may lead to interesting applications in optical devices. The enhancement of the GH shift is accompanied by the enhancement of the intensity of the decaying field in the optically thin medium and of the propagating field inside the film.