What is a Cryptic Pregnancy?

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  • Risk factors
  • Psychiatric disorders
  • Pseudomenstrual bleeding and absence of nausea
  • Theories trying to explain cryptic pregnancy
  • Final remarks and future directions

Cryptic pregnancy is the phenomenon whereby women do not become consciously aware of their pregnancy until the last weeks of gestation or in some cases until they give birth. Many case studies report anecdotal cases where even relatives and family doctors do not become aware of the pregnancy. Cryptic pregnancy is, in many cases, characterized by pseudo-menstrual bleeding and lack of typical pregnancy symptoms such as nausea, sickness and vomiting. Current estimates show that 1 in every 475 women experience cryptic pregnancy undiscovered until the 20th week of the pregnancy.

The consequences of cryptic pregnancy, including psychological distress, unassisted delivery and neonaticide, put both the mother and the newborn at risk.

Pregnancy test. Image Credit: Paul Velgos / Shutterstock

Risk factors

There has been no established clear-cut topology of the group women whereby the incidence of cryptic pregnancy is the highest. The majority of women studied, contrary to common beliefs, had good social support, leading to the conclusion that external stressors and conflicts can have an adverse effect in otherwise well-adjusted women.

Thus, women who undergo cryptic pregnancy are part of a heterogeneous group with no clear-cut identifying characteristics. Therefore, doctors should be more aware of the possibility of cryptic pregnancy and undergo a thorough examination of women who present with symptoms associated with pregnancy.

Psychiatric disorders

Research has shown contradictory evidence regarding the association of cryptic pregnancy with psychiatric disorders. Psychiatric symptoms related to schizophrenia, depression or personality disorder are only prominent in a minority of cases, thus are not recognized as an essential feature of cryptic pregnancy.

Pseudomenstrual bleeding and absence of nausea

A study by Brezinka and colleagues reports that 26 % of the women in the study had amenorrhea (absence of menstrual bleeding). The majority of women reported bleedings as regular periods. Meanwhile, 26% had experienced nausea. More importantly, none of the women who reported not being aware of the pregnancy until delivery experienced nausea. These results suggest that there is an association between the absence of nausea and other symptoms such as reduced abdominal swelling and low birth weight. This might be the reason why pregnancy remains concealed and in many cases denied until the delivery of the child.

Human chorionic gonadotropin (hCG) is a placental hormone that plays a crucial role during pregnancy. This hormone is involved in many symptomatic aspects of pregnancy, by triggering the release of maternal progesterone and thus inhibiting menstruation. Research has also pointed out the role of hCG in pregnancy-related nausea.

Theories trying to explain cryptic pregnancy

The currently available evidence from the biological point of view of cryptic pregnancy is limited. Some epidemiological studies provide more insight into the topic. However, this evidence is indirect and not sufficient enough to inform explanatory theories. Women use bodily cues to determine whether they are pregnant or not. In the cases of cryptic pregnancy, these cues are reduced or absent. Therefore, in the absence of cues, pregnancy is not assumed.

The parent-offspring conflict has been one of the main frameworks used to understand the biological base of cryptic pregnancy. All factors and symptoms surrounding this phenomenon point to the fact that in this conflict the mother is the figure that benefits the most at the expense of the fetus. Three hypotheses have been formulated to explain the phenomenon in evolutionary terms. Caution should be given to the fact that these hypotheses are not mutually exclusive.

Hypothesis 1: According to this hypothesis, the parent-offspring conflict results in the low investment of the mother. Research speculates that disruptions of the genomic imprinting mechanisms should be involved in reduced maternal involvement. Evidence on the parenting-specific effects of hCG hormone strengthens this hypothesis. This hypothesis is consistent with increased fetal risk. However, the fact that neonates do not show any other obvious problems except for the reduced birth weight is not supportive of the hypothesis.

Hypothesis 2: This hypothesis looks into missed abortion as an explanation of the phenomenon of cryptic pregnancy. If a fetus whose production of hCG is near the mother’s rejection threshold survives the beginning of the pregnancy without abortion, it could survive until childbirth despite the mother’s low investment in the pregnancy.

Hypothesis 3: This hypothesis sees cryptic pregnancy as an adaptive mechanism in stressful life conditions. Research with an Australian sample supports this claim by showing a high incidence of psychosocial stress in mothers.

Final remarks and future directions

Up to date, cryptic pregnancy has been interpreted as a pathological manifestation of unconscious conflict. One of the most cited explanations for cryptic pregnancy is that the woman is not psychologically ready to accept the pregnancy and the implications of it. Pregnancy is not only associated with many biological changes in the woman’s body but also requires preparation for the childbirth and care, all being based on accepting the pregnancy and the fetus and the changes that they are about to bring.

The parent-offspring conflict theory provides a framework for the explanation of cryptic pregnancy although the insufficient evidence leaves rooms for several hypotheses about the physiological mechanisms involved. Future research at many levels including genetics is needed to understand this complex phenomenon.


  • Del Guidice, M. (2007). The evolutionary biology of cryptic pregnancy: A re-appraisal of the "denied pregnancy" phenomenon. https://www.ncbi.nlm.nih.gov/pubmed/16997498
  • Neifert, P. & Bourgeois, J. (2000). Denial of pregnancy: a case study and literature review. https://www.ncbi.nlm.nih.gov/pubmed/10920660
  • Wessler, J. & Buscher, U. (2002). Denial of pregnancy: population based study. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC65667/

Further Reading

  • All Pregnancy Content
  • Early Signs of Pregnancy
  • Is it Safe to Exercise During Pregnancy?
  • Pregnancy: 0-8 weeks
  • Pregnancy: 9 – 12 weeks

Last Updated: Sep 10, 2019

Written by

Mihaela Dimitrova

Mihaela's curiosity has pushed her to explore the human mind and the intricate inner workings in the brain. She has a B.Sc. in Psychology from the University of Birmingham and an M.Sc. in Human-Computer Interaction from University College London.

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