Can You Get Pregnant While on Your Period?
- Fysiobasen
- Dec 5
- 3 min read
The question of whether pregnancy can occur during menstruation is common — and many assume it’s impossible.
While the chance is generally low, the truth is more nuanced.
Yes, it is possible to get pregnant while having your period, though it’s not very likely.
To understand why, we need to look more closely at the menstrual cycle and the factors that influence fertility.
A Quick Overview of the Menstrual Cycle
A typical menstrual cycle lasts around 28 days, but anything between 21 and 35 days is considered normal.Ovulation usually occurs midway through the cycle — about 12 to 16 days before the next period — and this is when a woman is most fertile.
However, since sperm can survive inside the uterus and fallopian tubes for up to five days, and ovulation doesn’t always happen on schedule, conception can occur outside the expected fertile window¹.
How Pregnancy Can Happen During Menstruation
There are several reasons why pregnancy during menstruation is biologically possible:
1. Short Menstrual Cycle
If a woman has a short cycle — for example, 21–24 days — ovulation may occur soon after her period ends.If intercourse happens toward the end of menstruation, sperm can still be alive when ovulation begins.
2. Long Menstrual Bleeding
Some women have menstrual bleeding lasting seven days or more.If ovulation occurs early, an egg and sperm could meet while bleeding is still happening.
3. Irregular Ovulation
Factors such as stress, illness, or hormonal fluctuations can cause ovulation to occur earlier or later than expected.This makes “safe period” calculations unreliable².
Pros and Cons of Intercourse During Menstruation
Some couples experience increased sexual desire during menstruation and may find intimacy more relaxed at that time.However, there are both advantages and risks.
Pros:
Some women report less menstrual cramping after intercourse.
The chance of pregnancy is lower compared to mid-cycle (but not zero).
Cons:
There is still a possibility of conception.
Higher infection risk due to changes in vaginal pH and exposure to blood³.
Some people find it uncomfortable or unhygienic.
What Does the Research Say?
Scientific studies show that sperm typically live 3–5 days, but in rare cases, they may survive up to 7 days⁴.If ovulation occurs soon after menstruation, sperm introduced during the period can still fertilize an egg.
Therefore, if pregnancy prevention is the goal, contraception should be used at all times, regardless of the cycle phase⁵.
Irregular Cycles and Unreliable Timing
Women with irregular menstrual cycles are at higher risk of misjudging fertile days.This is common among teenagers, perimenopausal women, and those with polycystic ovary syndrome (PCOS).
Methods such as the “rhythm method” or periodic abstinence have high failure rates and shouldn’t be relied upon alone⁶.
Summary
It is possible to get pregnant during menstruation, though the risk is relatively low.The likelihood increases if you have a short cycle, long bleeding, or irregular ovulation.Since sperm can survive for several days, early ovulation can lead to fertilization even when intercourse happens during a period.
To prevent unintended pregnancy, use contraception consistently — no matter what day of the cycle it is.
Sources
Moghissi KS. Accuracy of basal body temperature for ovulation detection. Fertil Steril. 1976;27(12):1415–1421.
Wilcox AJ, Weinberg CR, Baird DD. Timing of sexual intercourse in relation to ovulation—effects on conception probability. N Engl J Med. 1995;333(23):1517–1521.
Wiesenfeld HC, Sweet RL. Progress in the management of pelvic inflammatory disease. Clin Infect Dis. 1993;16(Suppl 4):S460–S467.
Zinaman MJ, et al. Estimates of human fertility and pregnancy loss. Fertil Steril. 1996;65(3):503–509.
Trussell J. Contraceptive failure in the United States. Contraception. 2011;83(5):397–404.
Fehring RJ, Schneider M, Raviele K. Variability in the phases of the menstrual cycle. J Obstet Gynecol Neonatal Nurs. 2006;35(3):376–384.
