If you’re in limbo, waiting until enough time has passed to take a pregnancy test, you may be looking for early signs that a baby is on the way. Implantation bleeding — blood that results when a fertilized egg nestles into your uterine lining — can be one such sign.

If you notice some light spotting on your underwear, the million-dollar question will start zinging through your head: “Am I pregnant or is this the start of my period?”

It isn’t easy to tell the difference between implantation bleeding and an early period. But here are some signs to clue you in to what’s happening.

  • Color. Implantation bleeding is more likely to be a pinky-brown color. Menstrual bleeding, on the other hand, may start off light pink or brown, but it soon changes into crimson red.
  • Strength of flow. Implantation bleeding is usually super-light spotting. Your period may start off light, but the flow gets stronger.
  • Cramping. Cramping that signals implantation is usually light and short-lived. Cramping that comes from your period is usually more intense and lasts longer. Every woman has her own pain threshold: You know your body best, so listen to it.
  • Clotting. If you notice clots in the bleeding, you can be pretty sure that this is your period. Implantation bleeding will not produce this mix of blood and tissue.
  • Length of flow. Implantation bleeding lasts 1 to 3 days while your period lasts 4 to 7 days.
  • Consistency. Implantation bleeding is more like on-and-off spotting. Your period, however, starts off lightly and gets progressively heavier.

Other pregnancy symptoms

If you are at the start of a pregnancy, you may also experience:

  • mood swings
  • nausea
  • tender breasts
  • headaches
  • lower back pain
  • general fatigue

These early pregnancy symptoms are caused by the hormonal changes in your body working overtime to support a pregnancy. But let’s be honest, you can experience all of these symptoms during a period too.

The 2-week waiting time from ovulation to the next menstrual period can be pretty frustrating if you’re hoping to be pregnant. Interpreting the signs correctly can be tricky, but luckily, sometimes timing — in addition to the symptoms above — can help you pinpoint what’s going on.

Implantation bleeding and menstrual bleeding don’t happen at quite the same time. Implantation bleeding happens a bit earlier than when you would expect to get your period.

Let’s walk through the timing, so you can compare dates on your calendar. Day 1 of your menstrual cycle is the first day of your last period. Most women with normal cycles ovulate, releasing an egg from the ovaries, around day 14 to 16.

The egg itself is only viable for about 24 hours after being released, but sperm can live inside your body for 3 to 5 days. It’s hard to know exactly when fertilization occurs, but the fertilization window is likely the 6 days sandwiched around ovulation.

The fertilized egg then implants into the uterine wall around days 22 to 26 of your cycle. If your body follows a 28-day menstrual cycle, you won’t get your period until after day 28.

So, if you’re bleeding earlier and lighter than normal, there’s a good chance it’s implantation bleeding, not your period.

When to take a pregnancy test

Since it’s not easy to tell the difference between implantation or menstrual spotting, you should take a pregnancy test if there is a chance you could be pregnant.

Pregnancy tests measure the level of the hormone human chorionic gonadotropin (hCG) in your blood. This hormone is made by the placenta that nourishes the newly developing embryo.

A urine pregnancy test — which can be done at home — is 99 percent accurate, as long as the test is not expired and you take it after the first day of your missed period, according to Planned Parenthood.

Some highly sensitive urine tests can be used earlier, but know that you run the risk of a getting a negative result when you are, in fact, pregnant. If you do get a negative result, but you’re still feeling symptoms that make you think you’re pregnant, wait 7 days and retest.

A blood pregnancy test — administered at a doctor’s office — can detect pregnancy as soon as 11 days after conception.

Remember, though, that hCG isn’t produced until after implantation, so testing for pregnancy at the first sign of implantation bleeding is likely to result in a negative result.

If you’re wondering about bleeding after a missed period, chances are there is another cause.

Bleeding in the first trimester is common. In fact, research shows that a whopping 25 percent of women will bleed early in pregnancy. Still, any blood occurring during pregnancy is considered abnormal, and you should contact your doctor when it happens.

When the bleeding is light, it may be caused by pretty simple things. For example, your cervix is more sensitive and developing additional blood vessels, so sex or a pelvic exam can cause bleeding.

However, bright red or heavy bleeding during pregnancy can signal more serious issues. Here are some possible causes:

  • Subchorionic hemorrhage. This happens when the placenta detaches from the original site of implantation.
  • Ectopic pregnancy. Occurring in only 1 to 2 percent of pregnancies, this happens when the egg fertilizes outside the placenta. If you feel intense pain on one side or pain in your behind, contact your OB immediately to this one rule out.
  • Molar pregnancy. This happens when a mass of tissue develops from the implanted egg, instead of a baby.
  • Miscarriage. Miscarriage is also called spontaneous abortion, and is defined as pregnancy loss before 20 weeks. It is the most common pregnancy complication, occurring at a rate of 15 to 20 percent. Furthermore, 80 percent of miscarriages happen in the first trimester.

If your pregnancy test was positive and you’re still bleeding, no matter how light, be sure to contact your medical provider to make sure there isn’t something more serious going on.

Keeping track of what’s going on with your body can sometimes feel like a full-time job. It’s even more agonizing when you’re trying to figure out if you’re pregnant or not.

Take a look back at your calendar to determine when the first day of your last period was, as well as the potential date of conception. You might want to jot down the symptoms you’re having and your timeline so you know when it’s appropriate to take a pregnancy test.

If you have any questions or doubts about bleeding that doesn’t seem normal, call your doctor to determine next steps. The waiting game is hard when you’re wondering if you’re pregnant, but there is no substitute for peace of mind.