Why it typically takes weeks to actually get pregnant after you have sex

• It takes about two to three weeks to get pregnant after sex, since implantation takes time to occur.
• If you don't want to get pregnant after unprotected sex, you can opt for Plan B or Ella.
• If you do want to get pregnant, early signs like fatigue and breast tenderness may signal pregnancy. 

Sure, unprotected sex leads to pregnancy, but it's so much more complex than that. Various processes must occur after a penis ejaculates inside a vagina, and this won't always lead to a viable pregnancy. 

A fertilized egg is a great first step, but it doesn't stop there, and it may take longer than you think before you are officially considered pregnant.

Here's what you need to know about how long it takes to get pregnant after sex, early pregnancy symptoms, and what to do if you don't want to get pregnant.

How long it takes to get pregnant after sex

Pregnancy doesn't happen immediately after sex, since the official beginning of a pregnancy is when a fertilized egg implants into the uterine lining, which can take up to two to three weeks after having sex 

For a clear picture of what happens during those two to three weeks, here's a step-by-step peek into how pregnancy starts:

Step 1: Can take minutes to five days. In order for an egg to be fertilized, it has to join up with a sperm. When you ovulate, your body releases an egg from an ovary in preparation for fertilization. This egg travels to the fallopian tube, where it remains for 12-48 hours.

Sperm can live for up to five days, so if you ovulate at any point within that time period, it's possible for a sperm to fertilize the egg you've just released. However, if you've just ovulated and then had unprotected sex, fertilization can occur much quicker. 

Step 2: After step one is complete, this step can take three to eight days. The egg and sperm join in the fallopian tube, creating an embryo. This embryo will then travel down the fallopian tube to the uterus for about three days, says Dr. Iris Insogna, an OB-GYN and fertility expert at the Columbia University Fertility Center.

Once the embryo has entered the uterus, it may float around for an additional few days, Insogna says.

Step 3: After step two to complete, this step can take five to six days. During this time, the embryo may implant itself in your uterus. Insogna says implantation itself involves multiple steps:

1. The embryo aligns itself with a spot on the outermost layer of the endometrium (the uterine lining). 
2. Trophoblasts (the cells on the outer layer of the embryo) adhere to the uterine cells. 
3. The trophoblast cells invade the uterine lining.

This process occurs over the course of a few days, which means it takes several days (around five or six) after fertilization for implantation to occur and pregnancy to officially begin. That said, around 50% of fertilized eggs do not implant, and a pregnancy does not occur. 

What if you don't want to get pregnant?

If you don't want to get pregnant, you have various options.

Your first option should always be using a type of birth control, but emergency contraception can end a pregnancy if you have had unprotected sex. 

If it's been less than five days, options include the following: 

• Ella is a prescription emergency contraceptive. This pill is FDA approved to take up to five days after unprotected sex. It's most effective for people under 195 pounds. 
• Plan B, or a generic variation of Plan B, is also an option. Yen says that there is less wiggle room with Plan B, as it has to be taken less than three days after unprotected sex, and is most effective for people under 165 pounds. 
• An IUD (either a copper IUD or a hormonal IUD) is the most effective form of emergency contraception, says Yen. However, it is the most permanent and involved form. If you get an IUD placed within five days of sex, you only have a 0.1% chance of getting pregnant. As a bonus, these serve as long-lasting birth control to prevent pregnancy in the future. 

Whether you are opting for Ella or Plan B, the sooner you can take the pill, the greater the chances of successfully preventing pregnancy. 

If you already are pregnant and do not want to be, you can opt for an abortion. There are two types:

1. Medical abortion 

A medical abortion, also known as medication abortion or at-home abortion, involves taking two types of medications that work to terminate the pregnancy. 

First, you take mifepristone, which blocks progesterone, a hormone necessary for pregnancy, says Yen. Next, 24 to 48 hours later, you take misoprostol, either by letting it dissolve under your tongue, in between your gums and cheeks, or vaginally. 

This medication causes cramping and bleeding as it expels the pregnancy tissue from the uterus, Yen says. Medical abortions are most effective within the first eight weeks of pregnancy. If the abortion is unsuccessful, you may need to take more medication or have a surgical abortion to complete the process. 

2. Surgical abortion 

Surgical abortions or in-clinic abortions are procedures completed by a doctor. To prepare for the procedure, you may take medication or use dilator sticks to help open up your cervix. 

Then, a tube is inserted through the cervix. Lastly, Yen says your provider will use a suction device to empty out the contents of your uterus. Your provider may also use a tool to scrape out any remaining pregnancy tissue to ensure everything is out. 

Early pregnancy symptoms

The most common indication of possible pregnancy is a missed period. When it comes to physical symptoms, everybody is different, but common early pregnancy signs include:

• Breast tenderness and swelling
• Fatigue
• Frequent urination
• Nausea

"Some women experience these symptoms as early as the first two to four weeks of pregnancy, though others may never experience them," Insogna says. 

Several less common early pregnancy symptoms are:

• Aversions to food
• Bloating
• Congestion in the nasal passages 
• Cramps
• Constipation
• Mood changes

Additionally, some people experience a type of spotting called implantation bleeding, says Yen. This occurs when the egg successfully attaches itself to the uterine lining. Yen says sometimes people mistake implantation bleeding for a period. However, this bleeding is much lighter and should only last a day or two. 

Insider's takeaway

Every pregnancy will be different and it may take shorter or longer for a pregnancy to begin,  depending on when the egg is fertilized. However, it can take up to a couple of weeks after sex for a pregnancy to formally establish. You may experience common early pregnancy symptoms such as breast tenderness or nausea.

If you don't want to be pregnant, you can use emergency contraception if it's within five days of unprotected sex. If pregnancy is already established and you don't want to be pregnant, you can opt for a medical or surgical abortion.