Background: Assisted reproductive technology (ART) is generally safe, but still associated with risks of various adverse maternal and neonatal outcomes.Methods: This retrospective cohort study included all deliveries (through either ART or unassisted pregnancy) during a period from January 5th, 2015 to September 30th, 2020 at the Obstetrics and Gynecology Hospital of Fudan University, Shanghai, China. A propensity score-matched (PSM) analysis was conducted to compare adverse maternal and neonatal outcomes between ART and unassisted pregnancy. The PSM was performed at a 1:4 ratio using a caliper width that equals to 0.02 of the standard deviation of the propensity score logit. The results are presented as relative risk (RR) and 95% confidence interval (95%CI).Results: We screened a total of 78,022 deliveries: 4,310 (5.5%) through ART and the remaining 73,712 (94.5%) through unassisted pregnancy. The ART group had older age (33.2±3.9 vs 30.4±4.0 years), higher rate of cesarean section (70.2% vs 38.1%) and multiple pregnancies (23.6% vs 1.7%). In the PSM analysis (4,218 and 15,003 deliveries, respectively), the ART group had higher risks of preeclampsia (10.5% vs 5.7%, RR: 1.57, 95%CI: 1.44-1.71), gestational diabetes mellitus (19.5% vs 16.0%, RR: 1.27, 95%CI: 1.16-1.38) and placenta-related diseases, including placenta previa (2.7% vs 1.8%, RR: 1.52, 95% CI: 1.21-1.89), placenta accreta spectrum (6.8% vs 3.0%, RR: 1.95, 95%CI: 1.72-2.22) and abnormal placental morphology (8.4% vs 5.5%, RR: 1.22, 95%CI: 1.14-1.30). In singletons, the ART group had higher risks of large-for-gestational-age (LGA) (13.7% vs 10.2%, RR: 1.40, 95%CI: 1.25-1.57) and stillbirth (0.3% vs 0.1%, RR: 2.24, 95% CI: 1.25-4.03) but lower risk of small-for-gestational-age (SGA) (4.2% vs 5.4%, RR: 0.84, 95%CI: 0.73-0.97). In multiple births, the ART group had lower risks of SGA (13.4% vs 17.8%, RR:0.83, 95%CI: 0.74-0.93), preterm birth (44.8% vs 59.2%, RR: 0.56, 95%CI: 0.49-0.64) and stillbirth (0.1% vs 0.6%, RR: 0.42, 95%CI: 0.20-0.90). Analysis of the overall, pre-matching study population yielded largely similar findings.Conclusion: Pregnancy through ART was associated with higher risks of most maternal outcomes. Interestingly, the risks of neonatal outcomes differed between singleton and multiple birth groups.

Welding is a manufacturing technique that joins metal or other thermoplastic materials in a heated, high-temperature, or high-pressure manner. Harmful dust and the light from welding can cause great harm to the human body. In addition, to improve welding quality and efficiency, intelligent welding has become an urgent need in the manufacturing industry. Herein, a dual-station intelligent welding strategy is designed based on an industrial charge-coupled device (CCD) visual detection system and welding control system. This solves the problem of expensive laser vision sensors and the poor detection effect of the visual system under the conditions of a short distance and strong light intensity. In the actual environment, there is the problem of radial distortion that affects the edge of the image, and the problem of the optical axis of the camera not being consistent with the installation plane. In this study, the camera coordinate system and hand–eye coordinate system are calibrated separately. The abovementioned problems are solved, and the images obtained by the CCD are acquired and processed in real-time. Image segmentation was performed using neighbourhood average filtering, iterative threshold segmentation, and local information extraction. The edge amplitude image was obtained by the Prewitt operator. Under the Hough transform method, the recognition of the weld seam and the extraction of weld feature points are realised. We designed an intelligent weld detection system that contains a friendly human–computer interface. Through numerous repeated experiments on circular and square workpieces, the control error of this intelligent welding system is within 0.2 mm, and the time of single seam feature extraction is 0.8 s.

Abstract

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