After unprotected sex, motile sperm can survive in a woman’s reproductive tract for five days. However, they can only reach the egg if they are exposed to fertile cervical secretions.
Each time a man ejaculates, millions of sperm are released. Those that survive the acidic vaginal canal will move towards the fallopian tubes to meet waiting eggs.
The First 24 Hours
Sperm can survive up to five days in the female body, but only if they’re in the right conditions. This includes the right temperature, humidity, and nutrient supply.
The first 24 hours are the most crucial for sperm, and it’s during this time that they’re able to enter the vagina. When a man ejaculates, around 100 million sperms are released into the vaginal canal. However, only a few of these will survive this acidic environment and make it to the cervical fluid.
Once the sperms reach this area, they begin swimming toward the fallopian tubes. Luckily, the cervical mucus is ideal for sperm survival because it creates a protective gel that shields them from the vagina’s acidity.
After about 30 minutes, the sperms are able to swim more freely as they move up through the cervix. It’s at this point that the fastest sperms may reach the fallopian tubes, but pregnancy won’t happen until an egg is released from the ovaries and fertilizes them.
It’s also important to note that urinating after sex does not flush sperm from the body. The urethra is a different tube than the vagina, so sperms are still able to reach the uterus and fallopian tubes. They will lose their motility, though, and will soon die if exposed to air outside the genital tract.
The Next 24 Hours
In normal conditions, sperm can survive inside the female reproductive tract for up to five days after being ejaculated. This is because cervical mucus is a hospitable environment for sperm, protecting them while also allowing them to move freely and fertilize an egg.
But outside the body, sperm’s lifespan is much shorter. On a dry surface like skin, sperm can only live for about 30 minutes. This is because they require the right moisture values to survive. On a surface inhospitable to them, like a hot tub, they die within seconds. The only way sperm can survive on its own is in a cryogenic chamber, where they can remain viable for years.
During the fertile window, a woman’s cervical mucus is especially hospitable to sperm. During this time, hormones change the consistency of cervical mucus from dense to egg-white. This provides a sperm-friendly host environment that’s perfect for the journey to the fallopian tubes, where an egg is waiting.
Unfortunately, even if you have sex during the fertile window, you’re not guaranteed to get pregnant. That’s because sperm may reach the fallopian tube but miss the egg completely, or it may be blocked by the uterus. That’s why safe, protected sex is so important to conceive. It gives you the best chance to reach and fertilize the egg during your ovulation window.
The Next 48 Hours
Once sperm enters the vagina, it encounters cervical mucus, which does two things: protects sperm from the acidity of the vagina and rejects sperm that are too big or misshapen to reach an egg. The thick, protein-rich fluid also provides a sperm-friendly environment that allows sperm to swim through the cervix (the thin fold of tissue that covers the top of the uterus) into the fallopian tubes.
A man releases around 100 million sperm each time he ejaculates, but not all of them survive the trip through the cervix to the fallopian tubes. Those that do can then swim up through the uterus into the pelvic canal and await the arrival of an egg from the ovaries, but the process takes days to complete.
Outside the body, sperm has only about an hour to fertilize an egg, which is why many couples are surprised to find out that sperm can stay alive up to five days once they are inside a woman’s reproductive tract. The sperm survival rate, however, largely depends on a woman’s menstrual cycle, particularly the condition of her cervical mucus.
Mucus becomes thinner, more sticky, and egg-white as a woman nears ovulation, making it an ideal environment for sperm to thrive. That’s why it’s important to accurately track your ovulation schedule when trying to conceive—having sex a few days before and during ovulation offers the best chance of pregnancy.
The Next 5 Days
Each time a man ejaculates, about 100 million sperm are released. Only a small fraction of them will endure the tough journey into the woman’s vagina, the cervix and into the fallopian tubes to search for an egg. If one of these sperms finds the egg and fertilises it, pregnancy can occur.
It is not just the location of the egg that determines whether a woman becomes pregnant after unprotected sex, but the consistency and quality of her cervical mucus as well. The cervical fluid is host to sperm and provides them with the nutrients they need for their mission. If this cervical fluid is fertile, sperm will be able to survive in it for a longer period of time.
But if the semen is dry and exposed to air, sperm will die within minutes. This is why it’s important for couples to have sex during a woman’s “fertile window,” which occurs in the days leading up to and during ovulation.
Sperm can live inside a woman’s reproductive tract for up to five days when they are hosted by fertile cervical mucus. However, if sperm enter the uterus and are unable to find and fertilize an egg, they will die. It is estimated that fewer than 10% of sperm that reach the uterus will succeed in fertilising it.
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