What exactly is a basal body temperature?
It is important for her to take her temperature before eating, drinking, or going to the bathroom and before any sexual activity. All of these things raise the heart rate and, in turn, the body temperature from its baseline level.
By recording the temperature level every morning over a period of months, a pattern can be seen. Being able to predict when ovulation is just about to occur and therefore when the woman is most likely to be fertile can be useful for couples who are trying to conceive.
Will just a normal thermometer do?
It is important to follow the manufacturer’s instructions when using a basal body thermometer. Each design varies slightly and to ensure accuracy it is important to follow the steps in their correct use.
The thermometer needs to be placed under the tongue and left there until it beeps. If you are using a mercury thermometer, then it needs to be left for 3 minutes to gain an accurate reading.
When do I start taking my basal body temperature?
Keep your chart, a pen, and thermometer beside your bed so they are easy to reach. Even the simple action of getting up and retrieving these from somewhere else like your bathroom may elevate your temperature and give false results.
How do I chart my basal body temperature?
- Take your temperature and mark an X in the first column marked Day 1 of Cycle in the box where the date and temperature lines intersect. Connect each dot with a line and see if over the month there is a variation as the line goes up or down. Over time, you are likely to see a pattern of degrees which reflect your ovulation patterns.
- You may prefer to write the day’s temperature on a notepad and chart it later or write up the day’s temperature directly onto your chart. Whatever works for you is fine.
- Make sure you write up the date and month which you started at the top of the chart. For each new month and each menstrual cycle, it is important to start a new chart.
- For each day of the month when you had intercourse, circle the dot on the corresponding day or place a mark in the box at the bottom of the chart.
- Remember, it’s not so much the individual temperature measurement which is important but the pattern of change between the first and second halves of the cycle. Generally, there is a lower temperature recording in the first half (before ovulation) and a higher spike (after ovulation) in the second half.
- The general recommendation used to be that women needed to take their basal body temperature vaginally rather than under their tongue. But the accuracy of today’s thermometers means that taking a vaginal temperature reading is no longer necessary.
What temperature changes am I looking for?
Generally, it is necessary for women to chart their basal body temperature for around 3 or more months before they see a predictable pattern occurring. It takes time to build confidence in being able to predict ovulation through temperature variations and other body changes.
What other changes can tell me I’m ovulating?
Does keeping a basal body temperature chart work?
How accurate is it?
Keeping a record and then interpreting the pattern of temperature rises and falls will help you to know when your most fertile time frame is likely to be. But remember, this is not a guarantee that you will conceive and there are multiple factors which need to align before conception occurs.
Not all women have a rise in their temperature when they ovulate. Although this is seen as normal, it’s not a consistent pattern among all women. Some who are very fertile and who have no problems at all with their ovulation won’t experience a measurable rise, while others who are infertile will consistently show a mid-cycle rise in their temperature.
What can I do to boost my chances of getting pregnant?
The information of this article has been reviewed by nursing experts of the Association of Women’s Health, Obstetric, & Neonatal Nurses (AWHONN). The content should not substitute medical advice from your personal healthcare provider. Please consult your healthcare provider for recommendations/diagnosis or treatment. For more advice from AWHONN nurses, visit Healthy Mom&Baby at health4mom.org.