Using BBT Charting for fertility
What is a BBT chart?
Basal body temperature is called the BBT. The BBT chart is where you take your temperature on a daily basis before you get out of bed. Our temperature changes according during our menstrual cycle. This can assist you to understand your menstrual cycle, to help you predict when you ovulate and also if you are pregnant.
What does a BBT chart show us?
The BBT chart gives us information about our entire menstrual cycle. The chart shows the different phases of the menstrual cycle. Our temperature changes according to the hormones that are secreted in our body. It tells us if the phases are at their optimal length for fertility, or not. It can show us what aspects of our menstrual cycle are in balance or whether there is a need help to regulate the cycle and balance the hormones.
Some of the things a BBT chart can show us is if ovulation is occurring, if it is occurring early or late. If your fertile mucus is occurring at the right time and if our luteal phase is long enough for conception.
The Menstrual Phase
The menstrual phase is the first phase to the menstrual cycle. You start the BBT chart on day one of your period. Day 1 is the first day of flow. If you spot pre-period, it is part of the former cycle. With the menstrual phase, there usually is a drop in temperature from the luteal phase. If the temperature doesn’t drop until after the period, this may be a sign of heat or inflammation in your pelvic region.
The Follicular Phase
The next phase is the follicular phase. The follicular phase is dominated by estrogen which aids the thickening of the endometrial lining. During the follicular phase your ovaries are developing follicles for a mature egg to be released at ovulation. So the temperature and length of this phase is telling us about your eggs and endometrial lining.
The Ovulation Phase
The ovulation phase is when the LH (luteinizing hormone) peaks to promote ovulation. The ovulation phase is your fertile window and lasts 3 days before ovulation and a day or 2 after. One of the reasons for not falling pregnant might be that you are ovulating later or early than you think you are and missing the window of opportunity. Ovulation tests are not always accurate. For example, if you think you are ovulating on day 14 of your cycle, but you actually ovulate on day 17 then you won’t fall pregnant. So timing is very important. Once you have charted your BBT for a couple of cycles, and you are ovulating regularly then you can predict when you will ovulate and time appropriately.
There are many apps now that you can use to track your BBT. Fertility Friend is one of the oldest, Kindara is another, though there are many more.
How to record a BBT
- You will need a BBT thermometer. They are available at the clinic or chemist.
- You will need 4 hours of sleep minimum before you can take the BBT. Take the temperature immediately after you wake up, before you get out of bed.
- It is a good idea to take the temperature at the same time each day. If you change the time you take the temperature, please note it down on your chart and we need to take this into account when reading your chart.
- Note down things that can also can change your temperature – this includes sickness, alcohol or interrupted sleep.
- If you struggle to do your BBT you can now purchase tempdrop that automatically tracks your BBT for you. The series 8 apple watch also has a BBT function.
The Luteal Phase
The next phase is the luteal phase. During this phase our temperature rises higher than the follicular phase. This phase is dominated by progesterone. Progesterone keeps the endometrial lining thickened so if an embryo implants into the uterine lining it is well nourished and supported for pregnancy until the development of the placenta which happens in about week 9 of pregnancy.
This is a brief introduction to BBT charting. Learning and understanding your BBT helps you understand your cycle and timing of ovulation. You can even chart your BBT and do ovulation sticks to check the accuracy of the ovulation sticks.
In our online courses, Kickstart your Fertility and Get Your Body Baby Ready, you can support your fertility journey, whether you are trying for natural conception or using assisted reproduction including Invitro fertilization (IVF) or Intrauterine insemination (IUI).
There are many apps now that you can use to track your BBT. Fertility Friend is one of the oldest, though there are many more.
How to record a BBT
- You will need a BBT thermometer. They are available at the clinic or chemist.
- You will need 4 hours of sleep minimum before you can take the BBT. Take the temperature immediately after you wake up, before you get out of bed.
- It is a good idea to take the temperature at the same time each day. If you change the time you take the temperature, please note it down on your chart and we need to take this into account when reading your chart.
- Note down things that can also can change your temperature – this includes sickness, alcohol or interrupted sleep.
- If you struggle to do your BBT you can now purchase tempdrop that automatically tracks your BBT for you. The series 8 apple watch also has a BBT function.
