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Can You Get Pregnant While on Your Period? Chances of Conceiving During Menstruation

Despite popular belief, it’s still possible to get pregnant during your period, and birth control is still necessary to prevent pregnancy. This is because it’s difficult to predict exactly when ovulation will occur.

Can you get pregnant while on your period?

The chances of getting pregnant while on your period are low, but pregnancy is still possible.

The answer lies in understanding the fertile window. For people who are trying to get pregnant, menstruation is not the best time to conceive. Getting pregnant depends on ovulation, which happens when an egg is released from the ovary and moves toward the uterus. The day of ovulation varies from one person to another and from cycle to cycle.

Although the chances of getting pregnant while on your period are low, there are exceptions. For example, it is possible to conceive during a period if ovulation occurs early in your cycle or if your periods last longer than five days. 

The chances of becoming pregnant during menstruation are higher for people with shorter monthly cycles. Shorter cycles (21–24 days or fewer) mean ovulation occurs early in the cycle. Because sperm can live for up to five days inside your body, having sex near the end of a period could lead to pregnancy if ovulation occurs early (within that five-day sperm survival window). 

Generally, most people ovulate sometime between days 10 and 17 of their menstrual cycle. The earlier ovulation occurs, the earlier the fertile window will start. The fertile window begins five days before ovulation. If ovulation occurs on day 14 of a cycle, then the fertile window starts on day nine. But if ovulation occurs on day eight of a cycle, the fertile window begins on day three — possibly in the middle of a period. 

Not all fertile days are equal. The days closer to ovulation have higher chances of pregnancy than the ones further from ovulation. 

Having unprotected sex a day before ovulation typically results in about a 30-percent chance of pregnancy. Having sex five days before ovulation involves about a 10-percent chance of pregnancy. This means that even if ovulation occurs early enough to start in the last days of your period, the possibilities of becoming pregnant on these days are not high.

Can you get pregnant right before your period?

The chances of getting pregnant right before your period are extremely low. For people with regular cycles, ovulation likely occurs 10–16 days before the next period. The eggs released during ovulation can only be fertilized for 12 to 24 hours.  

Сonception is least likely on the days before a period starts.

About 24 hours after ovulation, the chances of becoming pregnant start to decrease. The more days that pass after ovulation, the lower the chances of conception become.

Can I get pregnant the day before my period and still have a normal period? 

This is a question Flo users often ask, maybe because of the misconception that it’s not possible to get pregnant during a period. 

You can't get pregnant a day before your period, as ovulation will have occurred 10-16 days before the period (and not one or two days before).

Regardless of when conception happens, periods stop. 

Nevertheless, some people experience spotting during ovulation and mistake it for period blood. In fact, ovulation is the most fertile day of a cycle. Having unprotected sex during ovulation spotting can result in pregnancy.

Sometimes, people may also mistakenly assume implantation bleeding (spotting) is just a period. Actually, implantation bleeding is an early sign of conception.

Can you get pregnant right after your period?

Yes, it is possible to get pregnant right after a period if the fertile window starts immediately after menstruation ends. Sperm can live for up to five days inside the body. If bleeding stops on day six, sex happens on day seven, and ovulation occurs on day 11, the sperm from day six may still be in the uterine tubes. In this case, pregnancy is still possible. The likelihood of pregnancy after a period increases with every day after bleeding has stopped. 

For people trying to conceive, this can be an ideal time to try. Having sex every day increases the chance of conception.

Best time to get pregnant after a period

The likelihood of becoming pregnant is highest during the two days before ovulation begins or exactly on the day of ovulation, when an egg is released from the ovary. Usually, ovulation happens about two weeks (10-16 days) before the start of the next period. Cycles and ovulation dates vary, so you may want to try an efficient method of predicting ovulation to improve the chance of conception.

Here are four methods for predicting ovulation; they can help you find the best time to get pregnant after your period:

  1. For regular cycles with the same number of days each month, an ovulation calculator can help determine the most fertile day of the month. 
  2. Tracking the signs and symptoms of ovulation, like changes in basal body temperature and cervical mucus, can also help determine the best time to get pregnant after your period.
  3. Use ovulation predictor kits to pinpoint egg release.
  4. Log your menstrual info in Flo and predict your fertile days using our AI-enhanced algorithms.

Can you have a period and still be pregnant?

No — once pregnancy begins, the uterine lining no longer sheds each month. Once the body starts releasing a hormone called human chorionic gonadotropin, monthly periods will stop. However, some people experience light bleeding after conception, around the same time their period would have started. This is called implantation bleeding

If you’re pregnant and experience bleeding or spotting, contact your health care provider.

Birth control to avoid getting pregnant on your period

Pregnancy can occur even if you’re on your period. To avoid pregnancy, it is important to use contraception.

Birth control methods that can prevent pregnancy on your period include:

  • Male condom
  • Combined oral contraceptive pill
  • Progestogen-only pill (mini-pill)
  • Contraceptive patch
  • Long-acting reversible contraception, like an implant or intrauterine device
Arévalo, M, et al. “A Fixed Formula to Define the Fertile Window of the Menstrual Cycle as the Basis of a Simple Method of Natural Family Planning.” Contraception, U.S. National Library of Medicine, Dec. 1999, www.ncbi.nlm.nih.gov/pubmed/10715371.

Blake, Khandis R, et al. “Standardized Protocols for Characterizing Women's Fertility: A Data-Driven Approach.” Hormones and Behavior, U.S. National Library of Medicine, May 2016, www.ncbi.nlm.nih.gov/pubmed/27072982.

Dunson, David B, et al. “Changes with Age in the Level and Duration of Fertility in the Menstrual Cycle.” Human Reproduction (Oxford, England), U.S. National Library of Medicine, May 2002, www.ncbi.nlm.nih.gov/pubmed/11980771.

Sohda, Satoshi, et al. “Relationship Between the Menstrual Cycle and Timing of Ovulation Revealed by New Protocols: Analysis of Data from a Self-Tracking Health App.” Journal of Medical Internet Research, JMIR Publications, 27 Nov. 2017, www.ncbi.nlm.nih.gov/pubmed/29180346.

Stanford, Joseph B, et al. “Timing Intercourse to Achieve Pregnancy: Current Evidence.” Obstetrics and Gynecology, U.S. National Library of Medicine, Dec. 2002, www.ncbi.nlm.nih.gov/pubmed/12468181.

Wilcox, A J, et al. “The Timing of the ‘Fertile Window’ in the Menstrual Cycle: Day Specific Estimates from a Prospective Study.” BMJ (Clinical Research Ed.), BMJ, 18 Nov. 2000, www.ncbi.nlm.nih.gov/pmc/articles/PMC27529/.

“Implantation Bleeding: Normal in Early Pregnancy?” Mayo Clinic, Mayo Foundation for Medical Education and Research, 9 May 2019, www.mayoclinic.org/healthy-lifestyle/pregnancy-week-by-week/expert-answers/implantation-bleeding/faq-20058257.

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