(Reuters) - Shares of Evofem Biosciences Inc jumped as much as 38 percent on Monday after its birth control gel showed effectiveness in a late-stage study, bringing the first hormone-free contraceptive close to approval.

Male condoms and oral pills dominate the $5.5 billion contraceptive market in the United States. However, oral pills cause side effects such as bleeding between periods, mood swings and nausea in women.

“These results pave the way for Amphora’s disruption of the contraception market as a novel, highly effective, non-hormonal and woman-controlled method that finally answers women’s long-awaited desire to avoid hormones,” Roth Capital Partners analyst Yasmeen Rahimi said.

Evofem’s Amphora gel works by regulating vaginal pH within the normal range of 3.5 to 4.5, creating a hostile environment for sperm and certain viral and bacterial pathogens that can cause sexually transmitted diseases.

An estimated 16.5 million women in the United States do not use any method of contraception, according to the company, on fear of side effects, leaving them highly susceptible to unwanted pregnancies and sexually transmitted diseases.

Amphora was found to have an 86 percent efficacy rate in avoiding pregnancies and no serious side-effects were observed in the study, which evaluated about 1,400 healthy women belonging to the age group 18-35 years, Evofem said.

Condoms, the most common non-hormonal method of contraception, have an efficacy rate of 82 percent. The rate stands at about 91 percent for oral pills and intrauterine devices, according to brokerage Roth Capital Partners.

“Our research and current understanding of women suggests the time is now for there to be a new non-hormonal category in contraception,” Chief Executive Saundra Pelletier said on a conference call with analysts.

The company’s shares were up 22.6 percent at $4.28 in mid-morning trade after touching a high of $4.90.

Oppenheimer analyst Leland Gershell said he expects Amphora, the company’s lead product, to bring in sales of up to $415 million by 2032.

The company plans to resubmit the marketing application for Amphora in the second quarter next year and if approved, plans to launch the product in January 2020.

Evofem is also testing Amphora as a preventive treatment for chlamydia and gonorrhea - two of the world’s most common sexually transmitted infections.