-Kirsten and Brad Williams have been all-natural since 2003. That's when the couple started practicing natural family planning. -There is something really, really important for all women to know that you don't have to rely on somebody else, you can rely on yourself, and there are huge health benefits to this. To not have a whole bunch of chemicals that are foreign to your body, interfering with your body. -They now have two beautiful children and one on the way but Kirsten and Brad have used NFP to avoid pregnancy as well as to conceive. -Any medicine you take is always got side effects, and with this there isn't. It's just you and that makes the-- for us that was the biggest difference, it takes effort from both of you and it takes participation from both of you. You really got to both want to do it, but if it makes that much of a big deal in your life you put in the effort. -As natural family planning coordinator for the Archdiocese of New York, Katya Peter, helps couples looking to learn about NFP. -Natural Family Planning is a way of true family planning that monitors the biological markers in a woman's body, her cyclical variations so that a couple can always know when they're fertile or infertile. -There are three main natural family planning models used in the US, the Creighton Model, the Billings Tabulation Model and the Sympto-Thermal Model. The Sympto-Thermal Model uses temperature in addition to other markers of ovulation to track a woman's cycle. The Billings and Creighton models monitor fertility by looking at cervical fluid. -It's not just counting days and guessing. It's monitoring the bio markers that your body gives you, that a woman's body produces every month. So, it's not guessing, it's monitoring your-- the signs of fertility so you know when you're fertile and infertile. -Katya teaches the Creighton model, the same model practiced by Kirsten and Brad. -It works, it's easy to learn and easy to interpret. Women feel empowered when they know their cycle. Couples feel the confidence in the Creighton Model System because it tells you each day whether you're fertile or infertile. -We work alongside with doctors trained in NaPro Technology, which is a new reproductive science. It works naturally and cooperatively with the woman's cycle. -With the Creighton Model couple use a chart-like this one to track fertility. A woman monitors her cervical fluid throughout the day then at the end of the day she writes her observations and puts a corresponding sticker on the chart. A lot of time the woman would relay her observations to her partner and he'll put the information on the chart. -It's been amazing to watch your body from the inside so it appear on a page in front of you as you're writing things down as you go through a day. And thing that you didn't think were really all that relevant to what's happening on the inside actually show up. -Kirsten admits the first couple of weeks were challenging. -The biggest challenge was confidence in myself. It's all explained to you so nice and clearly and it's been taking it and making it your own, and having the confidence to say, "Yes, I know that this is the case." And having your partner have that confidence in you. -But it gets easier with time. -Once you get into trusting yourself a little more and your partner then trusts you by putting it down on the page and one cycle comes and your next cycle goes, and you're still not pregnant and it's working out. You do, you develop a trust in it. -And Kirsten says it had a positive impact on her marriage. -It gives him an insight into what's happening with me which made a huge difference to little nuances in your relationship. I think it enriches your relationship in a way that you didn't really have to put effort into it before you could just [unk]. Now, that's [unk] and so you do, you put an effort and you didn't have to in the first place. -Like on the days they have to say no to sex. -You can look at your life and say right, these are the nights we need to pick the non-romantic movies to watch or we will be practicing our Kiss Girls, and then when that's gone, the spontaneity is there or you have the ability to plan something that's a good evening or, you know, we'll get the bed-- kids to bed quickly and it's little things like that so there's an element of specialness to it. That if it's just available all the time that's sometime you miss. -And saying no on the right days can pay off when you're trying to avoid pregnancy. -If you have talked to the system correctly and use it correctly, then you can have 99.5% effectiveness to avoid pregnancy. -For more information about Natural Family Planning check with your local Catholic diocese, but don't worry if you're not Catholic, religious beliefs are just one of many reasons couples begin practicing NFP. Kirsten is Catholic but says faith was not the driving force behind her decision to try NFP. -It wasn't so much about the religious convictions because that had very little to do with it when we started it, and it had nothing to do with it. It was about health, it was about I was not feeling healthy and there's-- it didn't make sense to me. I wanted to feel healthier. I wasn't particularly happy with the birth control at that time and so we changed, and it has made an incredible difference to my health.