section_path: Research directions/Females
section_name: Females
paragraph_text: Females
  
  Improvements of existing birth control methods are needed, as around half of those who get pregnant unintentionally are using birth control at the time. A number of alterations of existing contraceptive methods are being studied, including a better female condom, an improved diaphragm, a patch containing only progestin, and a vaginal ring containing long-acting progesterone. This vaginal ring appears to be effective for three or four months and is currently available in some areas of the world. For women who rarely have sex, the taking of the hormonal birth control levonorgestrel around the time of sex looks promising.
  
  A number of methods to perform sterilization via the cervix are being studied. One involves putting quinacrine in the uterus which causes scarring and infertility. While the procedure is inexpensive and does not require surgical skills, there are concerns regarding long-term side effects. Another substance, polidocanol, which functions in the same manner is being looked at. A device called Essure, which expands when placed in the fallopian tubes and blocks them, was approved in the United States in 2002. In 2016, a black boxed warning regarding potentially serious side effects was added, and in 2018, the device was discontinued.