A cryptic pregnancy, also called a stealth pregnancy, is a pregnancy that conventional medical testing methods may fail to detect. Cryptic pregnancies aren’t common, but they’re not unheard of, either.

Television shows like MTV’s “I Didn’t Know I Was Pregnant” showcase extreme examples of this condition. But anecdotal evidence suggests that women might not be aware of their pregnancies in up to

It’s frustrating if you’re hoping to be pregnant, and become convinced that you are, only to be told that according to a blood or urine test, it’s not possible. A stealth pregnancy can make you feel mixed emotions, too.

It can also be scary and confusing to find out that you’re actually pregnant as late at seven, eight, or nine months into it. Some women with this condition are even taken by surprise by labor pains that are their first real “sign” of pregnancy.

Let’s take a closer look at the symptoms, statistics, and stories behind this real condition.

To understand how a cryptic pregnancy can go undetected, it helps to grasp what a “normal” pregnancy looks like in its early stages. In the United States, most people discover that they’re pregnant within 5 to 12 weeks after conception.

After missing a period, a home pregnancy test will generally indicate a “positive” result. Further urine testing, a blood test, and an ultrasound at an OB-GYN will then confirm the pregnancy. Most people notice symptoms of pregnancy such as tender and swollen breasts, mood swings, fatigue, and nausea early on during the first trimester.

When you’re having a cryptic pregnancy, nothing sets off the chain of events that leads to discovering that you’re pregnant. A pregnancy test may come back negative even after you’ve missed your period. You may dismiss early pregnancy nausea as stomach flu or indigestion.

Maybe you’ve been told that you have infertility, or your periods don’t come regularly to begin with, meaning that pregnancy isn’t a possibility you would be prone to consider.

If you’re pregnant but aren’t aware of it, missing pregnancy symptoms can add to the confusion. Especially if you’ve never been pregnant before, it’s easy to dismiss pregnancy symptoms such as fetal movement, slight weight gain, and fatigue as the result of dietary or lifestyle choices.

Low levels of pregnancy hormones can mean your pregnancy symptoms are very mild or close to impossible to notice.

Fluctuating hormones can lead to slight bleeding that resembles a period. If you’re not missing your period (or are very irregular to begin with) and feel mostly the same as usual, why would you take a pregnancy test?

This line of reasoning, combined with the common causes of cryptic pregnancy, is how many people can go months without knowing they’re pregnant.

Conditions associated with cryptic pregnancy include:

  • Polycystic Ovarian Syndrome (PCOS). This condition can limit your fertility, create hormonal imbalances, and cause skipped or irregular periods.
  • Perimenopause is the time between when your period begins to grow less consistent and when it stops completely, which is marked by menopause. Pregnancy symptoms like weight gain and hormone fluctuations can mimic perimenopause symptoms.
  • Birth control pills and intrauterine devices (IUDs) can make you feel confident that a pregnancy just isn’t a possibility for you. While these methods of preventing a pregnancy are very effective, there are instances when you can get pregnant even on birth control or with an IUD in place.
  • It’s possible to get pregnant again after a pregnancy and before your period returns. Since breastfeeding and hormonal factors can cause your body to delay ovulation and your period for several months after a birth, you may assume your symptoms are just your body adjusting to its postpartum state when you’re actually pregnant once again.
  • Low body fat and athletic activity can cause your period to disappear for months at a time. People who participate in high-impact sports may also have low levels of certain hormones, making it harder to detect a pregnancy.

Sources vary on how long a cryptic pregnancy can last. It’s hard to collect data on this point because people who aren’t aware of their pregnancy can only tell you when their pregnancy ended, not how long ago it began.

Anecdotal evidence suggests that a cryptic pregnancy can last longer than a typical pregnancy, perhaps related to very low hormone levels at the start.

On the other hand, there’s also a case to be made that lack of prenatal care, poor diet, and lifestyle choices made by a person who isn’t aware of their pregnancy could increase the odds of a preterm birth.

We don’t have much credible research to understand how a stealth pregnancy might be different in terms of length.

Pregnancy tests and even ultrasounds can appear negative if you’re experiencing a cryptic pregnancy. The reasons why will differ on a case-to-case basis, but essentially, the following applies:

If you have PCOS, missed or absent periods, are extremely active or athletic, or have given birth recently

You’re more likely to have fluctuating hormones if you fit into one of these categories. If your uterus is continuing to shed at least partially, or if you don’t get your period regularly, hCG (the pregnancy hormone) may not accumulate in a way that is significant enough to give you a positive home pregnancy test.

If you have an inconclusive ultrasound

Even an ultrasound can fail to find a growing fetus if it’s not looking in the right place. If previous testing has indicated that you aren’t pregnant, it’s also possible that an ultrasound technician isn’t going to spend a lot of time looking for a growing fetus.

If you’re approved to get an ultrasound despite a negative pregnancy test, it’s possible a pregnancy won’t show up in the first trimester because of:

  • an irregularity in where the embryo is implanted
  • the way your uterus is shaped
  • an error on the part of the ultrasound tech

Labor and delivery at the end of a cryptic pregnancy will be physically similar to any other pregnancy. You’ll typically have contractions that feel like severe cramps while your cervix stretches to be able to deliver the baby. Once your cervix is dilated, your body will need to push the baby out of the birth canal.

What’s different about labor and delivery for a cryptic pregnancy is that you may not be at all expecting it. This can cause intense psychological distress while it’s happening.

You also may not have had access to prenatal care during your pregnancy, so you might not have a doctor or midwife on call. If you’re experiencing intense cramping that feels like contractions and don’t know what to do, go to the emergency room immediately.

There are lots of stories of women who claim that they didn’t know that they were pregnant.

The medical literature points to who went to her local ER for lower back pain. Once she arrived, she took a routine pregnancy test before being checked in, which revealed that she was pregnant.

Even more surprising, when her doctors started to check her for an ectopic pregnancy, they discovered she was 8 centimeters dilated — nearly ready to give birth. She delivered a healthy baby boy.

NBC News reported on several of these “stealth birth” cases in 2009. According to their reports, one woman was rushed to the ER with what she and her family thought was appendicitis, only for the resident on call to discover that she was in the midst of labor by feeling the baby’s emerging head.

That baby, too, was delivered and remained in good health.

News reports and case studies aside, not every story of cryptic pregnancy has a happy ending. The best-case scenarios reflect stories of people who were living healthy lifestyles without knowing they were pregnant.

There are times when a pregnancy is undetected because the person carrying the pregnancy can’t acknowledge the pregnancy. These cases can be impacted by chronic mental illness or outside factors, like an abusive partner or an unsupportive family who would not accept the pregnancy.

There are also cases where individuals become pregnant in their early teens before they understand the symptoms of pregnancy.

The outlook for cases of stealth pregnancy when there is abuse, mental health conditions, or an extremely young person is statistically hard to calculate, but it’s safe to say it’s not as likely that the pregnancy will result in a healthy birth.

The biggest drawback in a cryptic pregnancy is being cut off from prenatal care. This isn’t a danger in and of itself, assuming that all is going well with your pregnancy — which you, ironically, couldn’t possibly know without getting prenatal care.

points out that without prenatal care, your baby is far more likely to be delivered prematurely and to be underweight at birth.

Cryptic pregnancy is a real condition, though it’s uncommon and somewhat misunderstood. If you believe that you’re pregnant, you should be aware that conventional first-trimester testing methods — blood tests, urine tests, and ultrasounds — are accurate for most pregnancies.

If you continue to have pregnancy symptoms after getting a negative home pregnancy test, discuss your specific circumstances with a doctor you trust. Waiting for a week or two to see if your symptoms subside won’t hurt your baby, but don’t delay seeking answers for months.

Remember that if you’re in distress or feel like you just can’t handle being pregnant, there are resources for you.