Kato K, Fujiki K Multiple Births and Congenital Anomalies in Tokyo Metropolitan Hospitals, 1979-1990. Acta Genet medicae Gemellol twin Res [Internet]. 2014/08/01. 1992;41(4):253-9. Available from: https://www.cambridge.org/core/article/multiple-births-and-congenital-anomalies-in-tokyo-metropolitan-hospitals-19791990/E0EFF17376931D73FB60D91C756B2864
Kong CW, To WWK The predicting factors and outcomes of caesarean section of the second twin. J Obstet Gynaecol. 2017 Aug;37(6):709-713. doi: 10.1080/01443615.2017.1286466. Epub 2017 Mar 21.
Mutihir JE PV Obstetric outcome of twin pregnancies in Jos, Nigeria. Niger J Clin Pract [Internet]. 2007;10. Available from: https://www.ajol.info/index.php/njcp/article/view/11301
Qin JB, Wang H, Sheng X, Xie Q, Gao S Assisted reproductive technology and risk of adverse obstetric outcomes in dichorionic twin pregnancies: a systematic review and meta-analysis. Fertil Steril. 2016 May;105(5):1180-1192. doi: 10.1016/j.fertnstert.2015.12.131. Epub 2016 Jan 19. Review.
Rzyska E, Ajay B, Chandraharan E Safety of vaginal delivery among dichorionic diamniotic twins over 10 years in a UK teaching hospital. Int J Gynaecol Obstet. 2017 Jan;136(1):98-101. doi: 10.1002/ijgo.12017. Epub 2016 Nov 3.
Obstetric and Neonatal Outcomes of Twin Pregnancy (Twin Conception-To-Birth): A Multicenter International Study
Interventional studies are often prospective and are specifically tailored to evaluate direct impacts of treatment or preventive measures on disease.
Observational studies are often retrospective and are used to assess potential causation in exposure-outcome relationships and therefore influence preventive methods.
Expanded access is a means by which manufacturers make investigational new drugs available, under certain circumstances, to treat a patient(s) with a serious disease or condition who cannot participate in a controlled clinical trial.
Clinical trials are conducted in a series of steps, called phases - each phase is designed to answer a separate research question.
Phase 1: Researchers test a new drug or treatment in a small group of people for the first time to evaluate its safety, determine a safe dosage range, and identify side effects.
Phase 2: The drug or treatment is given to a larger group of people to see if it is effective and to further evaluate its safety.
Phase 3: The drug or treatment is given to large groups of people to confirm its effectiveness, monitor side effects, compare it to commonly used treatments, and collect information that will allow the drug or treatment to be used safely.
Phase 4: Studies are done after the drug or treatment has been marketed to gather information on the drug's effect in various populations and any side effects associated with long-term use.