Julie Medical Advisor
Basal Body Temperature (BBT)
Understanding Basal Body Temperature: A Comprehensive Guide
For anyone who’s chosen the natural birth control route (aka, not using hormonal birth control or intrauterine devices), tracking body basal temperature (BBT) can help you determine when you ovulate so you can avoid sex or use a temporary form of protection when your chance of becoming pregnant is at its highest. BBT plays a unique role in reproductive health. Although some people swear by its use to prevent pregnancy, it’s not perfect and requires a lot of personal research ahead of time. Find out more about what your basal body temperature is, how it works, and how to measure it accurately to help you avoid pregnancy.
How does it work
First, it’s important to know that BBT and regular body temperature are not the same thing. Body temperature typically fluctuates throughout the day due to various factors, like exercise, eating, and your environment. On the other hand, BBT is your body's lowest resting temperature and is best measured in the morning before you even get out of bed.
When your BBT rises, that’s a sign that ovulation (when an egg is released from your ovary) is happening or has just happened. The temperature increase stems from the increased progesterone, a hormone responsible for preparing your uterus for pregnancy. Though it’s not an exact prediction of the moment you’re ovulating, tracking it over time can give you a sense of when it’s likely to occur. If you’re trying to prevent pregnancy, it can help you understand when to avoid sex (or take extra precautions) during your cycle.
Keep in mind: once you ovulate, the egg will survive in your fallopian tube for up to 24 hours before dissolving. But sperm can survive in your reproductive system for up to 5 days. If you have sex even a few days before ovulation, you have a higher chance of becoming pregnant. Learn more about conception here.
How to take basal body temperature
Start recording your BBT on the first day of your period. Continue to take it every morning throughout your next few cycles. It may take several cycles to notice a consistent pattern, so be patient.
Here are some other steps to keep in mind:
- Use the right thermometer: Make sure you have a thermometer that measures temperatures to at least one-tenth (or two decimal places) of a degree. This will help you detect subtle temperature changes.
- Take your temperature when you wake up: Keep your thermometer within easy reach next to your bed. When you wake up in the morning, take your temperature before you do anything else, even before you even sit up or reach for your phone.
- Consistency is key: Aim to take your BBT at the same time each morning. Waking up at different times can affect the results.
- Measure from the same place: Take your temperature from the same place on your body every day. Most measure in the mouth (like taking your regular body temp), but some prefer vaginal or rectal measurements.
- Record your temperature daily: Maintain a record of your daily temperatures using a graph, spreadsheet or fertility-tracking app. This will help you identify patterns and trends over time.
- Identify a temperature increase: BBT typically rises less than half of a degree Fahrenheit about halfway through your cycle. This increase is a key sign that ovulation is occurring or just did.
- Determine your fertile period: You’re most likely to get pregnant in the 5 days leading up to and 1 day after ovulation. Trying to conceive? This is your window to get it on. Trying to prevent pregnancy? This is your window to not get it on or to use a backup form of birth control, like condoms.
Why should I use the basal body temperature method?
The BBT method offers a natural and inexpensive way to track your menstrual cycle, fertility, and ovulation. It’s a great option for anyone looking to avoid the cost of hormonal birth control and the side effects that can come with it. However, becoming pregnant is the biggest side effect if the method fails.
What is a normal basal body temperature?
Everyone’s BBT is different but it only varies by a degree or two. Here’s the average estimate:
Before ovulation: The typical BBT range before ovulation falls between 96 to 98 degrees Fahrenheit (35.5 to 36.6 degrees Celsius). This represents your body's lowest resting temperature.
After ovulation: BBT typically ranges from 97 to 99 degrees Fahrenheit (36.1 to 37.2 degrees Celsius). The degree of increase can vary, with some individuals experiencing as little as a 0.4-degree Fahrenheit (0.22-degree Celsius) rise, while others may see an increase as high as 1 degree Fahrenheit (0.56 degrees Celsius).
How do I know when I’m ovulating using basal body temperature?
You won’t know you’re ovulating until you’re in the middle of it or it has passed (although your body can give you clues as to when you’re ovulating, called ovulation symptoms.) That’s why you should track your BBT through several menstrual cycles to understand when your BBT could rise. When your BBT has stayed at a higher temp for three consecutive days, that’s when you’ve most likely ovulated.
Basal body temperature while pregnant
If you become pregnant, your BBT should remain elevated above your pre-ovulation baseline, and you won’t see the drop that normally happens before a period is about to occur.
There isn't a specific "normal" range for BBT during pregnancy, just what’s normal for you.
Factors that affect your basal body temperature
BBT isn’t the most reliable method to prevent pregnancy because many factors, even common lifestyle ones, can influence it. Here are the things that are most likely to affect your BBT reading:
- Breastfeeding: Breastfeeding can affect hormonal levels, potentially leading to fluctuations in BBT.
- Drinking alcohol: Alcohol consumption can disrupt sleep patterns and, consequently, influence BBT readings.
- Fever caused by illness or infection: Elevated body temperature due to fever can temporarily raise your BBT.
- Not getting enough sleep: Sleep disturbances can affect the consistency of BBT readings.
- Stress: High stress levels can lead to hormonal fluctuations and influence your reading.
- Taking some medications: Certain medications can affect hormonal balance and BBT readings.
- Traveling to different time zones: Travel-induced sleep disruptions and changes in your daily routine can influence BBT.
Use Julie as a backup for the BBT method
Using the BBT method means staying on top of your daily menstruation cycle readings so you know when and when not to have unprotected sex. Miscalculations or errors can sometimes happen, and that’s okay.
Have Julie on hand as a backup to the BBT method. Julie, an over-the-counter morning-after pill, delays the release of the egg from the ovary. Take it ASAP within 72 hours (3 days) of unprotected sex. Note: Julie is not effective if you’ve already ovulated. Julie is FDA-approved and legal in all 50 states. Pick it up at Target, CVS, Walmart, or order it through GoPuff (and get it in 30 minutes). No ID, credit card, or insurance is required.
There are a few medications that may interact with the morning-after pill. The most common medications include:
-Some anti-HIV medications
-Some anti-seizure medications
-Rifampin (an antibiotic mainly used to treat tuberculosis)
-St. John’s wort
If you have concerns about a medicine you are taking potentially interacting with the morning-after pill, please consult with a pharmacist or medical provider.
No, studies have confirmed that taking two pills will not change the effectiveness of the morning-after pill, even for those with higher BMIs.
Essentially nothing. Julie is not an abortion pill and it will not harm or end an existing pregnancy. Julie helps prevent pregnancy by stopping or delaying ovulation, but if you’re pregnant, then there’s no ovulation to stop. The medication, levonorgestrel, won’t harm you or your fetus if you do end up taking Julie while pregnant. This makes Julie a great option for people who want to be safe after unprotected sex—if you aren’t pregnant yet, it may stop a pregnancy from occurring, and if you are already pregnant, it won’t impact the fetus.
No. The morning-after pill only stops ovulation short-term. When you take it after unprotected sex, it reduces your chance of getting pregnant now. When you start a new cycle next month, you’ll go through a brand new ovulation phase, which is a new opportunity to get pregnant. So if you’re planning on having babies in the future, rest assured your chances of getting pregnant won’t be affected by Julie.
After taking Julie you can continue on with your regular birth control method if you have one (for example, continue taking birth control pills).
You will know Julie has been effective when you get your next period, which should come at the expected time, or within a week of the expected time. If your period is delayed beyond 1 week, it is possible you may be pregnant. You should get a pregnancy test and follow up with your healthcare professional.
Julie is a backup or emergency method and should not be used as a regular birth control method. Consult with your doctor about a birth control method that makes sense for you.
Please know that taking a dose of Julie will only protect you from one instance of unprotected sex, it will not prevent pregnancy from unprotected sex over the coming days or weeks. If you have unprotected sex in the future and want to prevent pregnancy, be sure to take a new dose of Julie and talk to your doctor about the best birth control options for you.
Your menstrual bleeding patterns may change temporarily after using levonorgestrel. If you find that your period is more than a week late, take a pregnancy test to confirm whether the contraceptive has worked.
Technically, no. Julie can be used by anyone with a uterus regardless of weight. However, studies have shown that the effectiveness of the morning-after pill does decrease in people who have a body mass index (BMI) over 25. For those with a BMI under 25, pregnancy risk after taking the morning-after pill is less than 2%. For those with a BMI over 29.9, the risk of pregnancy increases to 5.8% - meaning that out of every 100 individuals with a BMI over 29.9 who take Julie, six may become pregnant.
Why? Unfortunately, we don’t really know. There is only preliminary research testing the efficacy of the morning-after pill on people with a BMI over 25 and 30. Read more here.
Julie is not an abortion pill and will not harm an existing pregnancy nor will it be effective if a woman is already pregnant.
Julie is a progestin‑only emergency contraception product that helps prevent pregnancy before it starts when taken within 72 hours after unprotected sex.
Julie is a backup method of preventing pregnancy and should not be used as regular birth control. Use as directed.
The medication in the morning-after pill, levonorgestrel, temporarily blocks or delays ovulation, which is when your ovary releases an egg. It essentially puts the emergency brakes on your ovaries so an egg can’t be released. If there’s no egg, then there’s nothing for sperm to fertilize, which means a pregnancy can’t develop.
Read more about how the morning-after pill works here.
The morning-after pill, like Julie, is 89% effective when taken within 72 hours (or 3 days) after unprotected sex. The golden rule is the sooner you take it, the better it will work.
One thing to note: Weight does impact the effectiveness of the morning-after pill. If your BMI is over 25, Julie may not be the best option for you, but there are other options if you have access to a medical provider. Ella® is another type of emergency contraception pill that works more effectively for women with a BMI under 30. Like Julie, it’s a one-time pill but it does require a prescription from your provider. Copper and hormonal IUDs are the most effective form of emergency contraceptive and are not affected by weight at all. However, they do need to be inserted by a healthcare professional up to 5 days after having unprotected sex.
Learn more about how weight impacts Julie here.
You do not need to see a doctor before or after taking Julie because the pill is available without a prescription. However, there are a few reasons you might want to speak with a doctor after unprotected sex. The first reason is that unprotected sex carries the risk of catching sexually-transmitted infections. The second reason is that the morning-after pill is not as effective as regular birth control. A doctor will be able to counsel you on better options if you plan to remain sexually active.
Since emergency contraception can affect the length of your menstrual cycle, your period might come about a week later or earlier than usual after taking Julie. If your period is more than one week late, consider the possibility of pregnancy.
No, the morning-after pill (including Julie) and the abortion pill are two very different medications. The morning-after pill prevents a pregnancy from starting by stopping an egg from being released. If there’s no egg, there’s no chance of pregnancy. Plus, it’s FDA-approved and legal in all 50 states.
On the other hand, the abortion pill ends an existing pregnancy, which is something that the morning-after pill cannot do. If you’re already pregnant, the morning-after pill and the medicine within it, levonorgestrel, cannot end the pregnancy or impact it in any way.
See more common morning-after pill myths here.
No. No one needs a prescription to purchase Julie or EC. However, some insurances require a prescription for reimbursement. Some pharmacies and places where EC is sold may tell you that you need a prescription. You do not.
The morning-after pill—like Julie— is one of the most common and convenient forms of emergency contraception. It’s an over-the-counter pill found at retail chains like Target, CVS, and Walmart nationwide. The morning-after pill is made of the hormone levonorgestrel, the same hormone found in many birth control pills and is FDA-approved and legal in all 50 states. When used correctly, it can significantly reduce your chance of getting pregnant. It doesn’t require a prescription, ID, or credit card, and can be purchased easily by anyone (you, your partner, your friend, or the nice guy from GoPuff). Learn more about the morning-after pill here.
The morning-after pill is a backup method of preventing pregnancy and should not be used as regular birth control.
You should take Julie if you had unprotected penis-to-vagina sex and:
- You didn’t use any form of birth control
- Your birth control method failed—e.g. the condom broke or slipped off
- You missed 2 or more doses of your regular birth control pill
- You’re not sure if he pulled out in time
Remember to take Julie ASAP to have the best chance of it working. It’s 89% effective when taken within 72 hours of unprotected sex, but can be effective up to 120 hours after. Learn more about Julie here.
No. No one needs a prescription to purchase Julie or other brands of the morning-after pill. However, some insurance companies require a prescription for reimbursement. Some pharmacies and other places where emergency contraceptives are sold may tell you that you need a prescription. You do not.
Take the Julie tablet orally (swallowed). It is preferable to take it with water, and you can take it with or without food. Do not insert Julie vaginally.
No. We know this is a common misconception so let’s break it down. Using Julie (no matter how many times you take it) does not affect your fertility — and it will not prevent you from becoming pregnant in the future. You should feel free to use Julie whenever you think it’s necessary. Julie (and all EC) is not recommended as an ongoing form of birth control because it’s not as effective at preventing pregnancy as birth control methods like the IUD, patch, pill, ring, or shot. Also, frequent use of EC may cause periods to become irregular and unpredictable. That’s it!
You can get Julie at your local CVS, Target, Walmart or on our website.
No, that’s not recommended. Emergency contraceptives, like Julie, work when you take them after sex. That’s because emergency contraception prevents pregnancy by delaying when you ovulate, which is when an egg is released from the ovary. Sperm can live inside you for up to 5 days, so if you take Julie and then have unprotected sex, the medication might not be able to delay ovulation for the entire length of the sperm’s life, creating a potential for pregnancy.
Learn more about how Julie works here.
Yes. You are not alone. Often times, people who buy EC are feeling stressed out, concerned, embarrassed, confused or ashamed. The important thing to remember is that you are not alone, you have nothing to be ashamed about, and the Julie community is here to support you. By taking Julie after unprotected sex, you are taking control of your future and taking a safe, effective, approved method of preventing pregnancy.
Julie and other over-the-counter morning-after pills contain a high amount of levonorgestrel, a synthetic hormone that’s also in some birth control pills. The extra amount of this hormone can affect your menstrual cycle and cause some side effects. Most side effects come and go within hours of taking the pill, but some can last up to a couple of days. Learn more about Julie's side effects here.
- Bleeding/spotting between periods
- Temporary changes to a period cycle (the next period comes early or late)
- Heavier or lighter next period
- Abdominal pain
- Breast tenderness
For more information about Julie side effects and how long they last, read this.
Side effects like nausea, abdominal pain, and fatigue can start within a few hours of taking the morning-after pill. If you vomit within two hours of taking the pill, it’s important to talk to a healthcare professional to find out if you should take another dose.
Most side effects are easily manageable, but sometimes they can be annoying. If that headache just won’t go away or your breasts are super tender, it’s safe to take ibuprofen, acetaminophen, or any over-the-counter pain reliever—they won’t interact or interfere with levonorgestrel.
Listen to your body. After all, you’ve just taken a pill that affects your hormones. Feeling a little weird is normal. Rest, keep yourself hydrated, and give yourself some extra compassion.
No. Julie is not what is commonly called “the abortion pill” or “medication abortion”. The active ingredient in the abortion pill is mifepristone. Pregnancy needs a hormone called progesterone to grow normally. Mifepristone blocks your body’s own progesterone, stopping the pregnancy from growing. Julie does not and will not impact an existing pregnancy, and works by delaying ovulation before there is a pregnancy.
The FDA recently made an update in December 2022 to remove any language suggesting that Julie may prevent implantation of a fertilized egg. We are currently working on removing this outdated disclaimer but you may still see it present on some of our packaging in the meantime. Please disregard these statements because they are out of date. Julie will not impact an existing pregnancy.
Your cycle might be temporarily affected after taking Julie. That’s because there’s a higher dose of levonorgestrel compared to what’s found in daily birth control pills. It’s likely to impact your body’s natural hormone levels for a short period of time. This might result in an earlier or later period.
If your period is delayed beyond one week, it is possible you may be pregnant. You should get a pregnancy test and follow up with your healthcare professional if positive. Your period might also be lighter or heavier than usual, or you might experience spotting in between cycles. If your schedule is impacted beyond a month or two, it’s worth checking in with your medical provider. Read more about how Julie might affect your period here.
No! The most common side effects are changes in your period, nausea, lower stomach pain, fatigue, headaches, dizziness, and breast tenderness. These symptoms typically go away within a few hours and shouldn’t last more than a couple of days. If you have any side effects that bother you, call your healthcare professional. Read more about Julie's side effects here.
Yes. You are not alone. Oftentimes, people who buy EC are feeling stressed out, concerned, embarrassed, confused or ashamed. The important thing to remember is that you are not alone, you have nothing to be ashamed about, and the Julie community is here to support you. By taking Julie after unprotected sex, you are taking control of your future and taking a safe, effective, approved method of preventing pregnancy. If you want to share your experience and talk with others in our community, head to our Tik Tok, Instagram, and Quora space, After Sex, where all sex questions and commentary are welcome.
It depends. Some people get their period a few days earlier or later than they were expecting, while some have reported a delay in menstruation beyond a week. Stress can also delay your period, which can be heightened when taking emergency contraception. If your period is more than one week late, it doesn’t necessarily mean that you’re pregnant, but it is recommended to take a pregnancy test.
Waiting for your period to arrive can be stressful, especially after taking emergency contraception, but just know that it might be totally normal. A delayed or early period is actually one of the most common side effects of taking the morning-after pill. Levonorgestrel, the hormone in Julie, delays ovulation, which can move the timing of your cycle back a few days. Your period might also be lighter or heavier than usual, or you might experience spotting in between cycles. If your period is delayed beyond one week, it doesn’t necessarily mean that you’re pregnant, but it is recommended to take a pregnancy test. You can read more about how Julie might affect your period here.
The best thing to do after taking Julie is to rest and hydrate. If you’re feeling any side effects, you can take over-the-counter painkillers to make yourself feel more comfortable. A heating pad or hot water bottle can also help if you’re having stomach pain or cramping. If you can, a day on the couch with Netflix or a good book often does the trick. Read more about managing Julie side effects here.
Typically just for one menstrual cycle. Most people notice that their period starts either a few days early or a few days late, though some people have reported a two-week delay in menstruation. If you are not pregnant, your cycle should return to normal the next time you get your period. If changes last beyond a month or two, it’s best to check in with a doctor.
Read more about changes to your period after taking Julie here.