Q I have a personal question about pregnancy. I have been married for a year and do not wish to have a baby. My wife and I have been using the withdrawal method. When I get aroused, the tip of my penis will have some sticky fluid. Does this fluid contain sperm? Will my wife get pregnant if I do not pull out in time?
Occasionally during withdrawal, drops of my semen drip outside her private part. Will she get pregnant as a result? Does the sperm in the semen die when it touches air?

A The withdrawal method, or 'coitus interruptus', is a method of contraception in which the penis is removed from the vagina prior to ejaculation to avoid introducing semen into the vagina.

The sticky fluid that comes out of the tip of the penis when you are aroused is called pre-ejaculate. It is a clear, colourless, viscous fluid that serves as a lubricant for the movement of the penis and the foreskin. It is made up of small drops of semen that leave the penis before ejaculation. It may contain sperm, depending upon the length of time since the last ejaculation.

Sometimes it can be difficult for you to know when you are about to ejaculate. Therefore, if the penis is not withdrawn in time, a small amount of semen may be deposited in the vagina and impregnate your wife. The withdrawal method has a failure rate of about 30 per cent.

Semen that accidentally drips on the vulva can migrate up the female reproductive tract via capillary action. This can occasionally result in pregnancy.

With regard to the survival of sperm, it should be noted that sperm cells do not die when they are freshly ejaculated and in contact with air. They can survive 72 hours or longer under optimal conditions. This is especially so when they are deposited in the mucus secretion of the neck of the womb during ovulation.

If you have any questions, please e-mail them to sthealth@sph.com.sg

DR PETER CHEW, CONSULTANT OBSTETRICIAN AND GYNAECOLOGIST, GLENEAGLES HOSPITAL