Hi,
Welcome to the forum. I am really glad to help you out. Loss of one twin in the first trimester does not appear to impair the development of the surviving twin. However, fetal death occurring after midgestation (17 weeks' gestation) may increase the risk of IUGR, preterm labor, preeclampsia and perinatal mortality.
Consequently, serial assessments of fetal growth and well-being should be considered. Demise of one of the twins is common during the first trimester. The pregnancy should be continued. The risks to the other fetus are more only if the death occurs after 17 weeks of gestation. I sincerely hope that helps. Take care.