I had unprotected sex 6 days ago and I took the plain b pill 72 hrs after can I get pregnant?

When taken perfectly, meaning every day at the same time of day with no misses they can be as effective as 99.8 to 99.9% effective. BCP's do change your hormones. They work to supress ovulation. They thin the uterine lining (therefore the lighter periods-you still DO have a period on the pill) this is to help make the uterus a less hospitible place in case of an egg fertilization. Normally the uterus builds a nice plushy lining for the fertilized egg to implant itself into until the placenta fully develops. If there is no fertilized egg, the lining is shed as the menstrual "period". If the lining is thin, it is not as hospitable to the fertilized egg and the fertilized egg may not be able to implant and could just pass on out of the womans body instead of a pregnancy taking place. Another way BCP's work to prevent pregnancy is to thicken the cervical mucous to make it more difficult for the sperm to "swim" to find an egg ready for fertilization. So the pill works in these three ways to prevent pregnancy. BCP's do not protect against STD's so sometimes condoms are recommended unless you are monogamous and are sure your partner does not have an STD. Condoms still need to be used as back up protection if you miss a pill or are more than a few hours late in taking the Pill and also if you are placed on any antibiotic therapy because antibiotics decrease the effectiveness of the pill and a woman can become pregnant if she relies only on the Pill while she is on antibiotics. It is recommended that condoms be used in addition to the pill during the time you are on antibiotics and for at least 7 days after you finish them. BCP's do cause some weight gain in some women but others dont have any gain at all. The gain is usually around 5-10lbs although some women gain more and some less. Some women find that their acne clears when they are on the pill and many women who suffer from heavy debilitating periods find they have much lighter periods and less discomfort due to the pill. So the pill has its good points and its bad points. Plan B is believed to act as an emergency contraceptive principally by preventing ovulation or fertilization (by altering tubal transport of sperm and/or ova). In addition, it may inhibit implantation (by altering the endometrium or uterine lining). It is not effective once the process of implantation has begun. This is why it is so important to take it as soon as possible. It is not meant to be used as a form of birth control. It is not always effective and sometimes a woman becomes pregnant anyway especially the longer she waits to take it because implantation can occur before the Plan b pill can take effect. It wont stop a pregnancy once it has occured-once the fertilized egg has implanted into the uterine lining, Plan b cannot stop that and you are pregnant. There are other methods of birth control other than condoms and BCP's. Some women like the diaphragm. It is another type of barrier method. It is a little soft rubber like cup (it is usually made of a soft plastic) that goes up into the vagina and sits over the cervical opening blocking sperm from going into the uterus and therefore prevents fertilization. It is usually used in tandem with a spermicidal jelly. You put the spermicide around the inner circumference of the diaphragm to kill any sperm getting past the cup. Some women find this method spoils the sponteneity of sex because you have to plan for it and have the diaphragm in place a certain time before sex and you must remove it after a certain time after. Depo-Provera is another popular method because it is an injection you have to get every three months and after a few shots your period stops altogether so some women find this very convenient. There is also the IUD which is a plastic or metal device implanted into the uterus designed to prevent implantation. Some contain hormones they secrete and some do not. All methods of birth control have their good points and their bad points. You need to look over them all and consider your lifestyle and decide which one will work the best for you. Talk to your Dr and he/she will help you decide the best option for you. You age and smoking can be factors too. Really in this day and age there is little reason for accidental pregnancies. Birth control is readily available and some options are very inexpensive and dont need a Dr to get them for you.
good luck, I hope all turns out the best for you!