Some pregnancies are planned, and some pregnancies are unplanned, but few pregnancies go unnoticed. Not so cryptic (or “stealth”) pregnancies, which describe what happens when a woman goes through the bulk (or even all!) of a pregnancy without suspecting.
Psychological factors
Cryptic pregnancies have been linked to psychiatric disorders like schizophrenia, depression or personality disorder, but only in a small number of cases, and the evidence isn’t strong enough to prove these have anything to do with it. They have been more strongly linked with past traumas, especially child sexual abuse, sexual assault and domestic violence, and with fear of pregnancy, which appears in the majority of reported cases.
Sociological factors
In many examples of cryptic pregnancy, the women involved did at some point think they might be pregnant, but their circumstances were so unsuitable that they denied the possibility. Correspondingly, cryptic pregnancies often happen to soldiers or women with perilous home lives. This is known as somatic denial.
Biological factors
However, many scientists think that cryptic pregnancy is biological rather than psychological or sociological.
• Masking conditions
In many cases, cryptic pregnancies are masked by other conditions, such as Polycystic Ovarian Syndrome (PCOS), which reduces fertility, creates fluctuating cycle lengths, and hormonal imbalances, or the menopause, which causes changes in weight, suppressed menstrual cycle, and hormone imbalances.
Women who are on birth control, especially hormonal birth control, may not notice changes in hormones or loss of menstruation, as may not women who have recently given birth and are still waiting for their body to return to normal.
Highly athletic women or women who are severely underweight or highly stressed may lose their periods or find they come and go irregularly, making pregnancy unlikely and difficult to detect.
• Symptoms
Some women experience pseudomenstrual bleeding during pregnancy, and one study found that this was true of 74% of women with cryptic pregnancy[1]. Lack of morning sickness is also more common than in the general population, foetal movements mistaken for gas, and abdominal growth reduced, with the foetus sitting closer to its mother’s back, and often underweight.
• Testing
In some cryptic pregnancies, the women suspect early on, but test negative for pregnancy.
A home pregnancy test and even blood test can fail like this when hCG levels are low, which they typically are in cryptic pregnancies.
12-week ultrasounds can fail to detect a living foetus if its implanted in the wrong or an unusual place, the uterus is unusually shaped, or the ultrasound device or technician make a mistake. Uteruses that are tilted towards the back (uterine retroversion) or heart-shaped (bicornuate) can conceal a pregnancy or make a foetus hard to see. Scar tissue can also get in the way, such as marks from a caesarean or tummy tuck.
Scientists don’t know, but it’s generally agreed that somatic denial isn’t explanation enough. There are three main biological theories behind cryptic pregnancies[2].
1. Cryptic pregnancies may be a nonadaptive outcome of parent-offspring conflict – favouring the mother by giving her a bigger share of food, increasing her mobility, and making her less mate-dependent. This puts the foetus at risk, but the mechanism may have survived because babies born via cryptic pregnancies don’t seem to have anything else wrong with them except being undersized. The theory suggests this outcome is genetically driven.
2. Cryptic pregnancies may come about when the mother’s body tries to spontaneously abort a foetus, either because it’s low quality or because she can’t produce enough hCG to support it. However, if the foetus can make just enough hCG, it can grow despite maternal rejection and her own biological investment is suppressed.
3. Alternatively, a cryptic pregnancy could be an example of forced cooperation between mother and foetus under psychosocial stress. That is, the mother’s investment in the foetus is reduced, maximising her chances of surviving the stressful situation and therefore carrying the baby to term, at the potential expense of its overall health.
These theories may not be mutually exclusive.
We don’t know how long cryptic pregnancies last because the women who get them didn’t know about it at the time. However, some think they last longer or shorter than recognised pregnancies. There are good reasons for these theories.
The theory that they last longer is based on the idea that hormone concentrations are lower, slowing foetal growth and so demanding a longer term. Others think that lack of prenatal care and pregnancy-conscious dietary choices increase the odds of a preterm birth.
Sometimes, like in many cryptic pregnancies, there is no medical evidence of pregnancy, but the woman still labours under the impression that she is pregnant. This is known as pseudocyesis, or delusion of pregnancy, or phantom pregnancy, and is sometimes misnamed cryptic pregnancy. Phantom pregnancies can also occur in males, and can last significantly longer than recognised pregnancies, some for many years. We don’t know why phantom pregnancies come about, but it correlates strongly with the post-menopause period and weakly with psychiatric disorders including schizophrenia, other psychotic disorder, mood disorders and organic brain disorder[3][4][5][6].
There are many unknowns when it comes to pregnancy, and over the next few months, I’ll be exploring more of them with you. Look out for my next blog post, which will be about superfetation.
To read our full article on the things we don't know about pregnancy, check out our site. This article will be updated as we add posts across the coming months.
ReferencesHow does that even happen?
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| Pregnant woman via Pixabay. |
Cryptic pregnancies have been linked to psychiatric disorders like schizophrenia, depression or personality disorder, but only in a small number of cases, and the evidence isn’t strong enough to prove these have anything to do with it. They have been more strongly linked with past traumas, especially child sexual abuse, sexual assault and domestic violence, and with fear of pregnancy, which appears in the majority of reported cases.
Sociological factors
In many examples of cryptic pregnancy, the women involved did at some point think they might be pregnant, but their circumstances were so unsuitable that they denied the possibility. Correspondingly, cryptic pregnancies often happen to soldiers or women with perilous home lives. This is known as somatic denial.
Biological factors
However, many scientists think that cryptic pregnancy is biological rather than psychological or sociological.
• Masking conditions
In many cases, cryptic pregnancies are masked by other conditions, such as Polycystic Ovarian Syndrome (PCOS), which reduces fertility, creates fluctuating cycle lengths, and hormonal imbalances, or the menopause, which causes changes in weight, suppressed menstrual cycle, and hormone imbalances.
Women who are on birth control, especially hormonal birth control, may not notice changes in hormones or loss of menstruation, as may not women who have recently given birth and are still waiting for their body to return to normal.
Highly athletic women or women who are severely underweight or highly stressed may lose their periods or find they come and go irregularly, making pregnancy unlikely and difficult to detect.
• Symptoms
Some women experience pseudomenstrual bleeding during pregnancy, and one study found that this was true of 74% of women with cryptic pregnancy[1]. Lack of morning sickness is also more common than in the general population, foetal movements mistaken for gas, and abdominal growth reduced, with the foetus sitting closer to its mother’s back, and often underweight.
• Testing
In some cryptic pregnancies, the women suspect early on, but test negative for pregnancy.
A home pregnancy test and even blood test can fail like this when hCG levels are low, which they typically are in cryptic pregnancies.
12-week ultrasounds can fail to detect a living foetus if its implanted in the wrong or an unusual place, the uterus is unusually shaped, or the ultrasound device or technician make a mistake. Uteruses that are tilted towards the back (uterine retroversion) or heart-shaped (bicornuate) can conceal a pregnancy or make a foetus hard to see. Scar tissue can also get in the way, such as marks from a caesarean or tummy tuck.
 |
| Cat and kittens. By Laitche via Wikipedia Commons. |
Why does it happen?
Scientists don’t know, but it’s generally agreed that somatic denial isn’t explanation enough. There are three main biological theories behind cryptic pregnancies[2].
1. Cryptic pregnancies may be a nonadaptive outcome of parent-offspring conflict – favouring the mother by giving her a bigger share of food, increasing her mobility, and making her less mate-dependent. This puts the foetus at risk, but the mechanism may have survived because babies born via cryptic pregnancies don’t seem to have anything else wrong with them except being undersized. The theory suggests this outcome is genetically driven.
2. Cryptic pregnancies may come about when the mother’s body tries to spontaneously abort a foetus, either because it’s low quality or because she can’t produce enough hCG to support it. However, if the foetus can make just enough hCG, it can grow despite maternal rejection and her own biological investment is suppressed.
3. Alternatively, a cryptic pregnancy could be an example of forced cooperation between mother and foetus under psychosocial stress. That is, the mother’s investment in the foetus is reduced, maximising her chances of surviving the stressful situation and therefore carrying the baby to term, at the potential expense of its overall health.
These theories may not be mutually exclusive.
Does a cryptic pregnancy last longer than a recognised pregnancy?
We don’t know how long cryptic pregnancies last because the women who get them didn’t know about it at the time. However, some think they last longer or shorter than recognised pregnancies. There are good reasons for these theories.
The theory that they last longer is based on the idea that hormone concentrations are lower, slowing foetal growth and so demanding a longer term. Others think that lack of prenatal care and pregnancy-conscious dietary choices increase the odds of a preterm birth.
Phantom pregnancy
Sometimes, like in many cryptic pregnancies, there is no medical evidence of pregnancy, but the woman still labours under the impression that she is pregnant. This is known as pseudocyesis, or delusion of pregnancy, or phantom pregnancy, and is sometimes misnamed cryptic pregnancy. Phantom pregnancies can also occur in males, and can last significantly longer than recognised pregnancies, some for many years. We don’t know why phantom pregnancies come about, but it correlates strongly with the post-menopause period and weakly with psychiatric disorders including schizophrenia, other psychotic disorder, mood disorders and organic brain disorder[3][4][5][6].
There are many unknowns when it comes to pregnancy, and over the next few months, I’ll be exploring more of them with you. Look out for my next blog post, which will be about superfetation.
To read our full article on the things we don't know about pregnancy, check out our site. This article will be updated as we add posts across the coming months.
why don't all references have links?
[1] Brezinka, Christoph, et al. Denial of pregnancy: obstetrical aspects. Journal of Psychosomatic Obstetrics & Gynecology 15.1 (1994): 1-8. doi: 10.3109/01674829409025623.
[2] Del Giudice, Marco. The evolutionary biology of cryptic pregnancy: A re-appraisal of the denied pregnancy phenomenon. Medical hypotheses 68.2 (2007): 250-258. doi: 10.1016/j.mehy.2006.05.066.
[3] Yadav, Tarun, Yatan Pal Singh Balhara, and Dinesh Kumar Kataria. Pseudocyesis versus delusion of pregnancy: differential diagnoses to be kept in mind. Indian journal of psychological medicine 34.1 (2012): 82. doi: 10.4103/0253-7176.96167.
[4] Adityanjee, A. M. Delusion of pregnancy in males: a case report and literature review. Psychopathology 28.6 (1995): 307-311. doi: 10.1159/000284942.
[5] Chatterjee, Seshadri Sekhar, et al. Delusion of pregnancy and other pregnancy-mimicking conditions: Dissecting through differential diagnosis. Medical Journal of Dr. DY Patil University 7.3 (2014): 369. doi: 10.4103/0975-2870.128986.
[6] Manjunatha, Narayana, and Sahoo Saddichha. Delusion of pregnancy associated with antipsychotic induced metabolic syndrome. The World Journal of Biological Psychiatry 10.4-2 (2009): 669-670. doi: 10.1080/15622970802505800.
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