He's going to do it anyway so at least give him all the info you can on birth control and sexual diseases.

Something you might point out to him - the younger he starts to have sex, the more likely it is that he will contract a sexual disease over his lifetime. Think of it this way - if he starts to experience intimacy within a short period before he settles into a monogomous relationship, he will have had fewer partners and therefore exposed himself to fewer risks. The primary way to reduce the likelihood of contracting a sexual disease is to limit the number of sexual partners one has. Some diseases are not preventable by the use of a condom and he can be stuck with lifelong pain (i.e. outbreaks of Herpes). Do your research with a doctor or thorough web search and give him the facts. Don't tell him what HE should do; tell him only what YOU would do, considering all of the information.  There are other reasons to discourage a 14yr old from having sex, but your son probably won't be impressed by them so I don't suggest you even go there. Just start with the disease angle and see if you can help him to wait a couple of years longer!  Sarah Chana

I just came across this amazing answer for this question from Shmuely Boteach:

No Holds Barred: Sex is for adults

By SHMULEY BOTEACH Three weeks ago Oprah featured two 14-year-olds who had decided they were going to advance their relationship to full-on sex. The mother of the boy, hearing of his plans, bought him a pack of condoms, and put them in his drawer. Asked by Oprah why she bought the condoms, the mom said that if she had told her son not to have sex, he would not have listened. The mother was applauded for her open-minded realism.   Dr. Laura Berman, the expert on the show, said it is best to discuss with teenagers why they want to have sex and alert them to its full repercussions. The only person that seemed to disagree was Oprah's close friend Gayle King, who was adamant that the "couple" were way too young to have sex. "They don't even have driver's licenses," Gayle said.   I found this all pretty illuminating for what it says about the weakened state of modern parenting.   So let's set the record straight.
 1. Sex is for adults in a mature and committed relationship. It is not for kids, and not only because they can get pregnant or contract sexually transmitted disease. Sex brings a tidal wave of emotions which young teens are unequipped to assimilate either psychologically or emotionally. Many studies have linked teen sex to suicide, especially for young girls. Sex creates an artificial sense of closeness and when the relationship terminates (and terminate it will), it leaves a sense of abandonment and severe loneliness.   Moreover, when sex is experienced too early and without the proper emotional preparation, it becomes an empty experience leaving the participants disillusioned and dissatisfied. This explains why so many teens suffer sexual burnout by the time they hit their 20s with grave ramifications for future relationships. In The Kosher Sutra I discuss the shocking statistic that one out of three married couples in America is entirely sexless. I believe that one of the major contributing factors is the vacant sexual experiences that so many young Americans have.   Sex is also diluted when it is overused, especially in an inappropriate context. Later, when we try and draw upon its power to transform our relationship into one of exceptional intimacy and pleasure, we discover that it is powerless to do so.
2. The principal responsibility of a parent is to protect his or her child. Before we love them, before we inspire or educate them, our job is to guard them from harm. If our kids wish to drive a car we give them driving lessons in the belief that it is better to have them drive safely than dangerously. Likewise, no matter how powerless we felt to stop them from taking drugs, we would not go to the local pusher to get them a needle.   This does not mean that I judge the mother who was on the show. She loves her son and was doing what she thought was best. But our responsibility as parents is to have the kind of everyday, loving interactions with our children that allow us to play an active role in their lives and guide them toward positive choices. We dare never abdicate our responsibility through the fear of our own impotence. Indeed, I believe if we give up on our ability to empower our children to make moral choices, they will later hold us accountable. Our children must respect our advice and authority. That means that we can't allow them to drift so far from our influence that we suddenly find ourselves powerless to prevent destructive behavior.   Sure, we parents don't want to alienate our children by being party-poopers. That's why we have to balance discipline with inspiration, attention and love. There can be no substitute for regular family dinners, outings and parent-child conversation. If these central staples of family life are neglected, we will find ourselves in the position this mother did: feeling we have to go along with a child's destructive choice rather than prohibiting it for fear of losing the relationship. Which brings me to my next point.
3. We are not our children's friends. We are their parents. They have many friends. They have only one mom and dad. While it's wonderful to be popular with our kids, that popularity must be experienced within the overall framework of parental authority. We know what is best for our kids. We are older, wiser and more experienced. They must listen to us and we must take the unpopular stand of preventing them from engaging in activities that are against their interests.   We must tell our kids to turn off the TV and do their homework. We must tell our kids that if they are involved with drugs, they will disappoint us greatly and we'll be forced to punish them. And we must tell our kids sex is off limits and that if we see that their relationship is becoming too serious, we will move to terminate it. By all means give good, logical reasons. But be firm as well. Our children should of course love us. But they must also respect us. 
4. Fathers are the principal immunity for young girls to say no to sexual pressure. Where were the dads on the show? It is primarily a father who protects his teenage daughter from succumbing to the wiles of hormonal youths. Girls who are close to their dads are not desperate for male attention and are thus granted an invulnerability to the charms of silver-tongued 15-year -olds.
5. By allowing our sons and daughters to have sex too early, we gradually lose them to strangers. They suddenly get deeply and intensely involved with a non-family member. A 14-year-old girl should be much closer to her parents and siblings than her boyfriend. The former give her unconditional love that builds strength of character. The latter loves her for very conditional things like beauty, charm and a willingness to get physical. This fosters insecurity and an erosion of self-esteem.
6. We must teach our young sons to respect women. That comes from telling them it is unacceptable to see a girl as a means to sexual ends or to pressure her into having sex.
7. Relationship experts should not be averse to discussing morality. Part of teaching men and women how to make love work is to emphasize the moral dimension. Dr. Laura Berman did an admirable job of asking the right questions that led the young girl to pull back from wanting to have sex. But we relationship experts should not be dissuaded from discussing morals as well.   After discussing the issue of teen sex in all its aspects, there is nothing wrong with concluding definitively, as Gayle King did, that it's a bad idea for all involved.  

Sex in teens is so many times a desperate try to find a substitute for respect, proper acknowledgment and sometimes love that any child does not find at home. Because our teen children are persons too, and they do require all of the above. Further on, children do not just transform into adulthood by deep sleep method: so once they go adults they will be responsible...and they will know what to do when it comes to their sex lives...Sex is natural and it appears at the right time. The issue here is  how to teach a teen to use sex and not to be overwhelmed and overpowered by it? With much love and care, having in mind it is really your teen's intimacy he has some right to, also.
For me the main issue is to set healthy boundaries: why, who, when, how; set the difference between sex and porn: when you love each other it is sex, when you look at someone as her body parts it is porn and it leads to addiction and suffering
Also proper measure of prevention would be for the parents to peak a bit into their own intimacy issues and everyday relationship that the teen can observe.

Sex in teens is so many times a desperate try to find a substitute for respect, proper acknowledgment and sometimes love that any child does not find at home. Because our teen children are persons too, and they do require all of the above. Further on, children do not just transform into adulthood by deep sleep method: so once they go adults they will be responsible...and they will know what to do when it comes to their sex lives...Sex is natural and it appears at the right time. The issue here is  how to teach a teen to use sex and not to be overwhelmed and overpowered by it? With much love and care, having in mind it is really your teen's intimacy he has some right to, also.
For me the main issue is to set healthy boundaries: why, who, when, how; set the difference between sex and porn: when you love each other it is sex, when you look at someone as her body parts it is porn and it leads to addiction and suffering
Also proper measure of prevention would be for the parents to peak a bit into their own intimacy issues and everyday relationship that the teen can observe.

let him have it... = )

They're 14 Years old,you can let them do it.

I know how you feel. My boyfriend's niece is 14 and we have reason to believe she is thinking about having sex with her "first love." Whatever that can possibly mean at 14, who knows, but we made it clear that if this behavior continues there will be no more cell phone, no more boyfriend, and no license until she is 18 as opposed to 16. We know that this is extreme, but what else can you do? We realize that you cannot shelter them, but we don't want her to end up side tracking her life by getting pregnant in High School.

It is a duty of parents to inform their young adult offspring about human sexuality based upon reason, science and facts.  Individuals mature at different ages.  While most professionals indicate that the age of consent should be 15; many strongly argue that it should be 14.  Don't allow religious or cultural prejudices to rule.  Also don't look to the mass media for guidance.  Most television programs, such as "Oprah" reinforce the fears and preconceptions of the audience because this is what generates ratings.  I encourage you to inform yourself with the facts.  The books by Marty Klein, PHD (as well as his website) and by Judith Levine are great places to start.  Regardless ultimately it is your son's and his girlfriend's personal private decision.  Just make sure that you are not negatively judgmental.

is 15 yaer old girl is ready for sex????