You are here:

Urology/Pregnancy Chances


QUESTION: Hi, thank you for taking the time to answer questions.

My girlfriend and I recently had unprotected sex twice. Both times I pulled out. After the first time, a tiny drop touched her outer labia, which we wiped clean thoroughly with tissue about 10 seconds later.

I did not go to the toilet in between this point and thirty minutes later, when we did it for a short period again. Both times I came away from her vagina in time and did not ejaculate inside, although I realise that pre-ejaculate may have contained sperm the second time round.

Given that she's midway through her cycle, I realise that there's a good amount of potential that she was ovulating, although she has irregular periods.

Given that there's a 25-35% chance of conceiving when the man ejaculates inside a woman and the conditions are perfect, what percentage chance do you think she has of becoming pregnant? Taking into consideration that millions of sperm generally need to be expulsed into the woman in order for the few sperm remaining after the journey to have a chance of reaching the egg?

I realise that this answer may need to be given in a range. After all, the semen spilled may not have contained any sperm at all; or millions! But is it less than 10%, 5%, 1% or 0.1% or less, in your opinion? As I find that most answers online give disproportionate and uninformed answers from people who scream that they got pregnant from air.

An expert's guess, is all that I desire, as I realise a serious figure cannot be obtained!

I realise that this was naive of us and we will not be doing this again. It was a irresponsible to use the withdrawal method.

Thanks for your time


My guess would be 10% or less.  For such a smart guy, you are playing with fire trying the "withdrawl" technique during mid-cycle.  Either do something else, wear a condom or have your partner start on birth control measures if a pregnancy is not desired.  Now you have to wait and take your chances.

---------- FOLLOW-UP ----------

QUESTION: Thank you for taking the time to answer my question. I appreciate it greatly.

I was incorrectly informed as to when her last period was. That said, I know it was stupid.

Since asking the question, I watched a video narrated by Courteney Cox for the Discovery Channel. In that video, it's stated that 99% of sperm is killed before leaving the vagina and entering the uterus. What surprises me is that out of 250 million sperm, only a dozen or less make it to the egg in perfect conditions. That's why it seems that the withdrawal method, which has a failure rate of 15% or less a year according to studies, is bizarrely successful in reaching a pregnancy - given the fight that sperm face. Given this information, I would have put the risk at much less - more so in the 0.#% range. I can only presume that a few million sperm (at most) would have entered during our session (if that), given that precum is supposed to contain leftover sperm that isn't supposed to be strong enough to reach the egg on average in the first place.

Of course, all this information is taken from as much information as I could digest from the World Wide Web, and given your expertise in your field I know that you will have a good understanding of all of this, much greater than my own. But given that there's no release inside the woman, why is it still such a high risk? Is there something about sperm contained in precum that makes it particularly effective? Can you argue as to why the chances are so high? I know that during the perfect time, it's easier for sperm to travel, but it isn't that much easier from what I've read, and now watched.


The risk is there because of the possible presence of sperm in the pre-cum.  The fact is that there are not accurate statistics on this question and, of course, it only takes one.  By the way, under normal circumstances, usually around 250-300 sperm actually make it to any given egg.  Further, you had full, unprotected penetration so delivery may have happened near the cervix.

You insisted that I give you a guess so I did.  There is also the fact that when you are trying for a pregnancy, it's hard to get and when you don't want one, you get one!


All Answers

Answers by Expert:

Ask Experts


Stephen W. Leslie, MD


Questions concerning erectile dysfunction, kidney stones and prostate disorders including prostate cancer. I have a special interest in kidney stone disease prevention.


Full time practicing urologist with 30 years experience. Associate Professor of Surgery and Chief of Urology at Creighton University Medical Center. Editor in Chief of eMedicine Urology internet textbook. Author of only NIH approved book written for patients by a urologist on the subject of kidney stones "The Kidney Stones Handbook". Inventor of the "Parachute" and "Escape" kidney stone baskets and the "Calculus" stone prevention analysis computer program.

American Urological Association, Ohio State Medical Association, Sexual Medicine Society

Men's Health, Journal of Urology, Urology, Healthwatch Magazine, Emergency Medicine Monthly, eMedicine, "The Kidney Stones Handbook", and numerous articles in various newspapers. He is also the editor of the Urology Board Review by McGraw-Hill used by urologists to study for their Board Certification Examinations.

Graduate of New York Medical College with residencies completed at Metropolitan Hospital New York, Albany Medical Center and University of Wisconsin-Madison.

Awards and Honors
Thirlby Award of the American Urological Association. Rated as one the country's Best Urologists by the Independent Consumer's Research Institute

©2017 All rights reserved.