One of the questions I have heard so often from women is: "Can you get pregnant on your period?" The short answer is yes, it is possible to conceive while on your period, though it is fairly unlikely. To understand why, we will take a deeper look into the menstrual cycle, ovulation, and the conditions necessary for pregnancy to occur.
The Science of the Menstrual Cycle and Fertility
In order to understand how pregnancy could potentially occur during your period, you must understand the basics of the menstrual cycle and when exactly you can get pregnant during the cycle. A typical menstrual cycle lasts about 28 days, though it can range from 21 to 35 days in adults. Ovulation, the release of an egg from the ovary, occurs at the very end of the follicular phase (the first half of the menstrual cycle). This generally occurs around the midpoint of the cycle (day 14 in a 28-day cycle), but can vary depending on how long of a follicular phase you have or if any factors such as stress are causing delayed ovulation. The fertile window (the period during which pregnancy is possible) spans about 6 days — the 5 days leading up to ovulation and the day of ovulation itself.
Click here to read more information for understanding the complete menstrual and ovulatory cycles.
Click here to read my blog post about when a woman can get pregnant, which goes into greater detail about the fertile window.
Click here to read more information about the effects of stress on ovulation.
How You Can Get Pregnant During Your Period
1. Short Cycles and Early Ovulation: In women with shorter menstrual cycles (less than 21 days), ovulation can occur soon after menstruation ends. If intercourse happens towards the end of a period, sperm (which can live up to 5 days in the female reproductive tract) may still be viable when early ovulation occurs. Therefore, if you were to ovulate on day 10 of your cycle and had intercourse on the 5th day of your period, you could potentially conceive.
2. Long Periods and Overlapping Fertile Window: For individuals with longer periods (lasting more than 7 days), the fertile window may overlap with the final days of menstruation, especially in shorter cycles, creating a scenario where conception during menstruation is possible. For example, if your period is 8 days long, and you have sex on the 8th day of your period, you could potentially get pregnant if ovulation occurs on day 13 or earlier.
3. Misinterpreting Bleeding: Not all vaginal bleeding or spotting indicates a true period. Sometimes, bleeding that is thought to be a period can actually be ovulatory bleeding or spotting. Mid-cycle spotting during/close to ovulation can be completely normal, and this is different than an actual period. However, this misinterpretation can lead a woman to think she is on her period when she is actually near ovulation. Additionally, having bleeding between periods could also be due to other underlying causes such as a uterine polyp, endometriosis, or fibroids, and may not be due to a true period.
Deciphering Your Cycle: Is Your Fertile Window During Your Period?
With NFP (natural family planning), it is very important to understand the dynamics of the menstrual cycle in order to properly track and interpret your own cycle. This way you will better be able to know if you have conceived during your period or if this is possibility for you depending on your cycle specifics. While the textbook cycle is often cited as 28 days, with ovulation occurring around day 14, real-life menstrual cycles can vary significantly from person to person and even month to month. Tracking not only the days of menstruation but also other fertility signs (such as cervical mucus and basal body temperature) can provide a more accurate picture of one's fertile window.
Understanding and Tracking Your Cycle
1. Know Your Total Cycle Length: Start by tracking the length of your menstrual cycle for several months. A cycle is measured from the first day of one period to the first day of the next. Short cycles (less than 21 days) could mean your fertile window is close to or during your period.
2. Track Your Period Length: Charting your cycle includes keeping track of how long your period lasts. A normal period lasts anywhere between 3-7 days. If you are noticing that you are having abnormally long periods (lasting longer than 7 days), this could indicate that having sex during your period may lead to pregnancy. Click here for more information on my blog about irregular periods.
3. Monitor Ovulation Signs: Ovulation can vary widely among women and even from cycle to cycle. Key signs of ovulation include changes in cervical mucus (it becomes clear, stretchy, and lubricative much like raw egg whites), a rise in progesterone after the LH surge (monitored with urine hormone sticks), and a slight rise in basal body temperature (BBT).
A. Use Ovulation Predictor Kits (OPKs): OPKs detect the surge in Luteinizing Hormone (LH) that precedes ovulation by 24-36 hours. Using these kits can help you pinpoint ovulation more accurately, especially if your cycle's length fluctuates. Mira and ClearBlue are great brands you can use to monitor your hormone levels.
B. Track Cervical Mucus: Throughout your cycle, observe changes in your cervical mucus. Fertile mucus is clear, slippery, and stretchy, indicating ovulation is near. If you notice this type of mucus during or immediately after your period, your fertile window might overlap with menstruation.
C. Chart Your Basal Body Temperature (BBT): Taking your BBT every morning can provide clues about your cycle phases. A sustained rise in temperature typically indicates ovulation has occurred. Tracking over several months can help you identify patterns and predict future fertile windows. Both Natural Cycles and TempDrop are great apps that make monitoring your BBT simple. Otherwise, a cheaper option is buying your own BBT thermometer and logging each temperature daily. I would recommend the Easy@Home digital BBT thermometer.
For more information, read my blogs about how to get started with NFP and how to choose a method of NFP.
Conclusion
While the likelihood of conceiving during your period is low, it's not impossible due to the variability in menstrual cycle lengths, timing of ovulation, and the lifespan of sperm. For women using NFP or trying to conceive, it is important to have a deep understanding of you cycle and the biological principles of the menstrual cycle in general. As always, I encourage open discussions with your healthcare providers, especially if while tracking your cycle you are noticing any cycle abnormalities or reoccurring irregular periods.
Make sure to check out my Resources Page to see a list of different products, apps, and websites that can be helpful on your health and fertility journey.
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