The Trying to Conceive and Just Starting Out Primer

This is a "primer" created by Krista (Rudylover) and posted by Jennifer (Tigger062077). We made this as a source of information for the "newbies" who are afraid to ask a "silly question"...and for the "oldies" who have been doing this so long they've forgotten the basics.

If you want to reach us, you can reach Jennifer at and Krista at

Thursday, August 11, 2005

BBT: Is that some new Cable Channel??

BBT stands for basal body temperature, which means your resting body temperature. Charting your basal body temperature can often provide helpful information to women who are trying to conceive or are using natural family planning/fertility awareness method for birth control. The basic premise is this: your average temperature will be higher after ovulation than it is before you ovulate each cycle. After ovulation the corpus luteum produces progesterone, which is a heat producing hormone, which is why most women have a thermal shift after ovulation.

How do you BBT? You take your temperature every morning when you wake up before getting out of bed. It is best to take your temperature at the same time every day and after at least 3 hours of consecutive sleep. You then fill in the temperatures on a chart so you can see the pattern. You can do this online at Fertility Friend or other sites, or you can fill out charts on paper. Here is a link to a paper chart that you can print out: TCOYF

Most people find that using a digital thermometer works best. Many stores sell thermometers specifically for BBT, but as long as the thermometer displays temperatures to the nearest tenth of a degree (98.1, 98.2, 98.3…etc), it should work fine. [Caution: apparently there are thermometers out there that appear to display to the nearest tenth, but actually round to even tenths only (98.0, 98.2, 98.4…etc) which is not accurate enough.] The nicest BBT thermometers have a lighted display and memory. When you turn them on they display the last temperature taken. This allows you to take your temp and go back to sleep without writing the temperature down, as you can check the temperature later when you are ready to get out of bed. The BD Basal Digital Thermometer is one such product.

What should your BBT chart look like? Basically, your temps stay in a lower range before you ovulate and then after you ovulate the temps stay in a higher range and usually start to drop back down around the time of AF. If you are pregnant, the temps should stay higher. Some women get a temperature dip when they ovulate. Some women get a temperature dip when a fertilized egg implants as well.

You can see examples of charts that are filled out by real women on Fertility Friend. There is also a lot of great information in the book “Taking Charge of Your Fertility” by Toni Weschler, which tells you all about how to chart and what charting can show you in regards to pregnancy achievement, birth control, and menopause. TCOYF

Charting can show you several very important things that you may not know, otherwise. It can show you if you are likely ovulating, when in your cycles you ovulated, how long your luteal phase is, and if you have 18 or more days of sustained higher temps, among other things. According to TCOYF, if you have 18 days or more of sustained higher temps, you are most likely pregnant.

When you are charting for TTC, you should make sure you keep having intercourse regularly from the time you see fertility signs until your temps rise and stay higher. You usually ovulate on the last day of your temps being lower. Once the temperature rises, it is usually too late to conceive, but you should BD that day to cover your bases. After the temps rise and stay higher the egg is either fertilized or dead, so you can lay off the BDing at that time if you want to.

BBT is more helpful for some women that others. Some ladies have very ambiguous temperatures and they may find charting is more frustrating than anything. The nice thing is, charting costs you very little money, so if you abandon the practice you have not lost much.