Skip to main content

What is an implantation dip on a BBT chart?

What is an implantation dip on a BBT chart?

Some women in Australia will confirm that trying to conceive can be stressful. Most of these women wonder if they’re ovulating regularly and whether they can get pregnant after having unprotected sex during the fertile window. It’s also common to find women wondering if implantation has occurred.

The most obvious way to confirm whether you have conceived is to take a pregnancy test. However, there are other clues you can rely on aside from waiting to see those two lines on a pregnancy test, and this includes implantation dip. To understand more about implantation dip, you will need to familiarise yourself with basal body temperature or BBT.

How do you know if its implantation dip?
What causes an implantation dip?

How do you know if its implantation dip?

Implantation dip can simply be defined as a one-day drop of the basal body temperature (BBT) that occurs in the luteal phase of a menstrual cycle (approximately 7 to 10 days after you ovulate). Although anecdotal evidence suggests the drop in basal body temperature can be seen on pregnancy charts more than on non-pregnancy charts, an implantation dip doesn’t necessarily guarantee that you conceived.

Here is how you can recognise implantation dip on your basal body temperature chart, its causes, and the odds of being pregnant when you see one.

What link does it have with basal body temperature?

When you track your basal body temperature, a process known as ‘temping,’ you will learn more about your hormones and cycles and determine if you had a successful implantation process. This tracking is one of the options you can consider to monitor fertility, including cervical mucus tracking, ovulation prediction kits, medical procedures offered in doctor’s offices, and other fertility prediction apps.

Many women in Australia prefer BBT tracking because it is an affordable and painless way to check what is going on with your cycle. All you have to do is track the basal body temperature for at least three months to know the trends over time. The temperatures are logged in a chart, allowing one to view a biphasic chart, showing two phases.

One phase shows a lower temperature, and it is during this time, that the body’s hormones gear up and trigger ovulation. The second phase will show a slight temperature increase to signify ovulation has occurred. Note that your temperature may show a one-day dip, 7-8 days after you experience the slight temperature rise, which is what people call implantation dip.

What’s an implantation dip?

If you are searching for information regarding implantation dips, you likely know the basal body temperature charting basics. But if you do not know or require a refresher, here’s a summary review of how BBT charting works.

Your basal body temperature is your body’s temperature while at rest. The temperature changes depending on your external and internal environment and may be influenced by factors such as:

  • Temperature changes in your  indoor environment, particularly your bedroom
  • The quality or amount of your sleep (this includes the wake-up time changes)
  • Whether you are  on hormonal birth control 
  • Whether you have consumed alcohol
  • Whether you have a fever and are on medication to minimise the fever
  • Whether you are fighting an infection or illness
  • Your physical and emotional stress levels
  • Your hormone levels

If you want to understand implantation dip clearly, you will need to know how hormones impact your basal body temperature. Once you ovulate, the temperature will be higher by a few tenths of a degree, a temperature jump caused by increasing levels of hormone progesterone after ovulation.

Implantation dips are a 1-day temperature drop on a BBT chart and occur about a week after you ovulate. Normally, the temperature drop signifies that your period will be coming or it is about to start. The periods should not begin 7 –10 days after you ovulate, so you shouldn’t expect a temperature drop during this time.

With the implantation dip, the fall will only last for a day temperature will go up again the next day. This is different from what happens when your period starts, whereby the temperature drops and remains that way for some days. The dip may be slightly lower than the other post-ovulation temperature, or it can drop below the fertility chart’s coverline.

basal body thermometer: benefits of tracking
How to Detect Pregnancy or Ovulation on Your BBT Chart

What is a coverline?

A coverline is a horizontal line (imaginary line) on the BBT chart distinguishes the average temperatures before the ovulation process and the average temperatures after you ovulate.

A dip will appear during the cycle’s luteal phase, the period between ovulation and the next period. If an egg is fertilised, the embryo’s implantation will occur between the 7 and 11 of the luteal phase. So some women attribute the sudden temperature dip to implantation.

What is the cause of an implantation dip?

Regardless of the name, it is unclear if embryo implantation can cause a temporary basal body temperature drop. In some cases, non-pregnancy charts also have a dip, meaning that it is not a unique phenomenon that only occurs after conception.

One theory states that estrogen is responsible for the dip, as it peaks two times during each menstrual cycle. The first and largest surge usually occurs right before you ovulate, and it’s the primary cause of increased sexual desire and more fertile cervical mucus production. The second surge occurs in the middle of the luteal phase, but it’s not as high as the first one.

The progesterone hormone increases the body temperature while estrogen reduces it. The second estrogen surge may be the reason why women get implantation dips.

The estrogen levels are also high in pregnant women, which may explain why some women get a temperature decline on their pregnancy charts more frequently. But women who are not pregnant can also get secondary estrogen surges during a luteal phase, a reason why the dip may also appear on a non-pregnant chart.

Certain women also record a dip a day before ovulation, which is probably caused by an estrogen surge that occurs right before ovulation.

Does implantation dip signify that you’re pregnant?

An analysis of over 116,000 basal body temperature charts was studied to identify if an implantation dip on the user’s BBT charts indicated pregnancy. The findings were interesting. The analysis included charts for both non-pregnant and pregnant women and looked for:

  • BBT Charts that detected ovulation
  • After ovulation temperature dips by about 0.17℃
  • A temperature drop shows occurred within days 5-12 of the luteal phase

On the non-pregnancy charts, 11% of the women who recorded ovulation experienced an implantation dip, and 23% of the pregnant women also experienced an implantation dip. When you look at these findings, you will notice that more pregnant women had an implantation dip. On average, the dip occurred at 8-9DPO. 

About 79% of the BBT charts for pregnant women did not record a dip, meaning that if your chart does not have a dip, it is impossible to determine if you are pregnant or not. And since implantation dip also appears in some cases of the non-pregnancy charts, you cannot assume that you are pregnant if you see a dip on your chart.


Noticing an implantation dip on your basal body temperature chart could mean that you are pregnant, but it is not a surefire sign of pregnancy. Your BBT chart cannot clearly tell if you are pregnant, so you may need to take a pregnancy test to confirm this.