Does pulling out work for birth control?


Why Withdrawal?

“Pulling out” or withdrawal is a method that people use to prevent pregnancy. It's been around for a long time and lots of people use it. However, we--scientists--STILL don't know very much about how to use it and how effective it really is. Some men have used withdrawal their whole lives without any unwanted pregnancies, whereas others have been less successful…

We want to know why!

Our Questions:

  • If withdrawal is used correctly, is there sperm released in the pre-ejaculatory fluid ("pre-ejaculatory fluid") that can make a woman pregnant?

  • What makes someone more likely to have sperm in their pre-ejaculate?

  • What affects whether someone will have sperm in their pre-ejaculate? Age? Experience? Sperm count? Something else?

Our Study:

There are 3 parts to this study for couples:

  1. Survey: Couples will individually be asked to share their experiences with and use of withdrawal.

  2. At the lab: Male participants will be asked to come to our research center on 3 occasions to collect and provide both pre-ejaculate and ejaculate samples. These samples will be examined under the microscope to compare their sperm concentrations.

  3. At home: Female partners of these men will self-swab their vaginas before sex and after withdrawal is used for each time they use withdrawal with sex for a period of 2-3 months.

Keywords: withdrawal, birth control, family planning, pulling out

Study Sites

1200 N State Street, Los Angeles, CA 90033

  • Men & Women
Age icon
18 - 50

Please visit for more information.

Please text "withdrawal" to 323-797-4336 to see if you and your partner are eligible!


What's involved?

Study length
  • 2-3 months

Number of visits
  • 4 visits for male participants,

  • 1-4 for female participants

  • Masturbation for Semen Analysis in Clinic

  • Vaginal Swab Collection at Home

  • Compensation is available for successful completion of study visits.

Medical cost coverage
  • Study-related tests and procedures are covered.

Why participate?

Medical advances are impossible without volunteers.


Must have

  • Heterosexual couples
  • Willing to use withdrawal for study (other birth control also suggested)
  • Abstinence for 3 days prior to collection
  • Low risk for STI
  • English speaking

Can't have

  • Known or suspected low sperm count
  • Premature ejaculation
  • Genitourinary anomaly
  • Male urinary incontinence
  • Male neurologic impairment
  • Chronic vaginal product use
  • Pregnancy

About This Study

What we already know:

In 2012, Steven Killick and his UK lab tried to answer the question:
"Are there sperm released in pre-ejaculatory fluid that could make someone pregnant?

After examining 40 samples from 27 men, they found that only 37% of the pre-ejaculatory fluid samples had motile sperm (sperm that could successfully travel to an egg and fertilize it). They also noted that some men consistently had sperm in their pre-ejaculate and some did not!

Now in 2019, Dr. Jasmine Patel and her team at the EMERGE Lab are repeating this study with more critical attention and deeper questions. But we need your help... 

Study Team

Principal Investigator
Jasmine Patel

For questions about this study, contact:

Research study materials

We respect your privacy!

All the information you give us is stored in a secure, password protected database. All the information that you choose to share will be kept private and confidential. Read University of Southern California's Privacy Policy here.