Cryptic Pregnancy: How a Pregnancy Can Go Unnoticed

What is a cryptic pregnancy?

A cryptic pregnancy is one the pregnant person does not know about until it is well advanced, usually 20 weeks or later and sometimes not until labour. In medical research it is mostly called "pregnancy denial" or "denial of pregnancy"; reviews also search under "cryptic", "stealth" and "unperceived" pregnancy.

"Denial" here does not mean knowing and hiding it: a 2023 review defines pregnancy denial as "the lack of awareness of being pregnant". A pregnancy someone knows about and keeps from others is a different thing, which a 2011 review calls concealment.

How common is cryptic pregnancy?

Rare, but less rare than people assume. Over a year of births across Berlin in 1995 and 1996, 62 of 29,462 deliveries involved a woman who had not known she was pregnant, and had no doctor's diagnosis, until after 20 weeks: about 1 in 475. In 12 births, about 1 in 2,455, a viable baby was born to a woman who had not realised she was pregnant until she went into labour. The authors noted this is about three times as common as triplets.

For most people the unawareness ends partway through. In Berlin, 37 of the 62 pregnancies were diagnosed before labour, and the 2011 review notes the rate falls from about 1 in 475 at 20 weeks to about 1 in 2,500 at term.

How can you be pregnant and not know?

Usually because the usual signs are missing or seem to have another explanation. The 2023 review notes that, apart from a missed period, none of the early symptoms of pregnancy is a definite sign, so people with irregular periods, those using contraception and those who bleed in pregnancy are more likely to overlook them.

Bleeding that looks like a period

Menstruation-like bleeding is frequently reported in unrecognised pregnancies, the same review found. The NHS lists several causes of bleeding in pregnancy, including implantation bleeding in very early pregnancy, changes to the cervix, infection, miscarriage and placenta problems. See implantation bleeding vs a period for the earliest kind.

Contraception

In a French study comparing 71 women whose pregnancies went unrecognised with 71 whose did not, 75% of the first group had been using contraception, mostly the pill, against 7% of the comparison group. The NHS points out that no method of contraception is completely effective, and that the hormones in the pill will not stop a pregnancy test working.

Few symptoms and little bump

In these pregnancies, nausea, breast changes, a swelling tummy and weight gain are often absent or greatly reduced, the 2023 review reports. It describes a "silhouette effect": without a typical pregnant shape, nothing prompts the question. See when you start showing for how much that normally varies.

Other people miss it too. In one cohort in the 2011 review, 38% of the women had seen a doctor during the pregnancy without being diagnosed.

A negative pregnancy test

The NHS says a positive result is almost certainly correct, but a negative result is less reliable, particularly if you test too early. In a 2020 US hospital laboratory study, 11 of 9,447 negative urine tests were potentially missed pregnancies; testing early in pregnancy was the most common reason, followed by interference known as the beta-core "hook effect". Our page on pregnancy symptoms with a negative test covers retesting.

Who does it happen to?

Almost anyone. In a Berlin study of 65 women with unrecognised pregnancies, ages ranged from 15 to 44 with a median of 27, only 21 had never been pregnant before, and 83% had a close partner. The authors concluded the group was varied and no clear "type" could be identified.

The French study found some factors more common, including not being in a stable relationship, a psychiatric history, and a previous unrecognised pregnancy in yourself or your family. Even so, the 2023 review notes that most were mentally healthy: 23% had a psychiatric history, against 8% of the comparison group. Its conclusion: "Under certain circumstances, it can affect any woman."

Is a cryptic pregnancy risky for the baby?

The main problem is missed antenatal care. The 2011 review lists the outcomes reported in studies: unassisted or very fast births, preterm births, babies who are small for their gestational age, more admissions to neonatal care and higher infant mortality. It says at least some of these outcomes are potentially avoidable.

Once a pregnancy is recognised, care can start at any stage. For an unexpected birth, see unplanned birth at home or in an ambulance.

What to do if you think you might be pregnant

1. Do a test. The NHS says most tests work from the first day of a missed period, and that if you do not know when your period is due you should test at least 21 days after you last had unprotected sex. It lists sexual health services as a source of free tests, and says your GP may also provide one.
2. If it is negative but you still think you are pregnant, the NHS says to wait a few days and test again, and to speak to your GP if a second test is negative and your period has not come.
3. If it is positive and you plan to continue, the NHS says to tell it as soon as possible; in England you can refer yourself to a midwife. Elsewhere, contact a doctor or midwife; see our guides to UK antenatal and US prenatal appointments.
4. If you are not sure you want to continue, the NHS says you can discuss your options confidentially: continuing the pregnancy, abortion, or adoption.

When to get help urgently

If you are pregnant, including a pregnancy you have only just found out about, the NHS says to get urgent help for light bleeding or spotting with no pain or mild tummy pain, or with diarrhoea, or pain or pressure when you pee or poo: call your maternity unit, or NHS 111 if you do not have one yet. In the UK, call 999 if you are bleeding and:

• you have severe tummy pain
• you have pain in your shoulder
• you feel sick, faint or dizzy, or lose consciousness
• the bleeding is heavy, soaking a pad soon after putting it on

Outside the UK, use your local emergency number: 911 in the US and Canada, 999 in Ireland, 000 in Australia, or 111 in New Zealand.

Frequently asked questions

Can you have a period and still be pregnant?

You can bleed while pregnant, and it can look like a period. The NHS lists implantation bleeding in very early pregnancy among the causes of bleeding, and period-like bleeding is frequently reported in unrecognised pregnancies. The NHS says any bleeding in pregnancy needs advice from a healthcare professional, so test if you think you might be pregnant.

Can a cryptic pregnancy show up on a pregnancy test?

A 2023 review found no solid evidence that hCG, the hormone tests detect, is lower in these pregnancies. The NHS says a negative result is less reliable than a positive one, mainly when you test too early. If you still think you are pregnant, retest in a few days and see your GP if it stays negative.

What are the chances of a cryptic pregnancy?

Low. In a year of births across Berlin, about 1 in 475 pregnancies went unrecognised until after 20 weeks, and about 1 in 2,455 births of a viable baby came as a surprise in labour. Studies across Europe and the US give rates between 1 in 300 and 1 in 516. Most are recognised before birth.

What does a cryptic pregnancy belly look like?

Often like no obvious bump at all. A 2023 review found that a swelling tummy and weight gain are often absent or greatly reduced in unrecognised pregnancies, and calls this the "silhouette effect". That is one reason the pregnancy can go unnoticed by the person and by those around them.