While trying to get pregnant, you may experience spotting. It could be implantation bleeding, ovulation, cervical or uterine polyps, or a miscarriage. Here’s how to know the difference.

 

Dr. Nazaneen Homaifar

You’re trying to get pregnant, all seems to be going well, but you suddenly notice spotting in your underwear. Does it mean you’re not pregnant? Not necessarily. It’s very normal to experience a little bit of spotting during implantation—we’ll explain why that happens, and how to tell it apart from a regular period, below.

Back up—how does implantation work, again?

If you’re someone who falls into the category of regular cycles, around 28 days each, you’ll likely ovulate around day 14. During ovulation, your ovaries release an egg, which travels down the fallopian tube to the uterus. The journey down the fallopian tube can take a few days and if the egg is fertilized by a sperm, the fertilized egg, or embryo, usually travels down and implants into the uterine lining, or decidua. (The uterine lining is what your body sheds when you have your period—its intended purpose is to shelter a fertilized egg).

So, what’s implantation bleeding?

Implantation, when the fertilized egg burrows into the uterine lining, can cause a little bit of the lining to detach. If that happens, it can pass through your cervix and vagina and looks like spotting or a light period. 

It looks a lot like your period because it’s the same substance as your period—just less of it, and happening for a different reason. The timing also makes it easier to assume that implantation bleeding is actually your period—implantation happens around 10 – 14 days after fertilization, around the same time as your missed period. 

Implantation bleeding also seems like your period because it can bring the same side effects that periods can have: light cramping, mood swings, breast tenderness, nausea, and pain in your lower back.

In general, implantation bleeding is much lighter than most periods. It should cause spotting to a light period for a day or two. 

Other possible causes of bleeding 

When we think about bleeding in the preconception timeframe, it is useful to think about bleeding that happens between menstrual cycles or bleeding that happens after a positive pregnancy test. 

Spotting in between menstrual cycles can result from ovulation, cervical or uterine polyps, or from a friable cervix (irritation of tissue on the surface of the cervix). 

Bleeding after a positive pregnancy test can occur in 20-40% of pregnancies in the first trimester.

Keep in mind, most urine pregnancy tests won’t be able to pick up pregnancy hormone levels (beta human chorionic gonadotropin or b-hcg) until about three to four days after a missed period. Bleeding after a positive pregnancy test can occur in 15-20% of pregnancies in the first trimester. The frequency and volume of bleeding, along with other factors like ultrasound findings, play a role in helping to determine how concerning it is. Bleeding can be a sign of:

  • Miscarriage: if it doesn’t result in one, it is called a threatened miscarriage
  • Ectopic pregnancy: a pregnancy outside of the uterus, which is considered an emergency, but is overall rare (2% of pregnancies) 
  • Bleeding from a cervical, uterine, or vaginal source (infection, polyp, laceration, etc.)

When do I need to call my doctor?

While implantation bleeding is normal, it is usually considered a diagnosis of exclusion. That means a health care provider will want to make sure there are no other concerning reasons that could contribute to the bleeding. If you’ve had a positive pregnancy test and notice some bleeding, cramping, significant pain, fever, or chills, call your provider’s office to determine what the next best steps are. You know your body—if you think something’s wrong, trust that instinct.

Learn more about implantation bleeding and other early signs of pregnancy in our article, Is this Spotting My Period or am I Pregnant?