top of page

Research Supporting the Theories of Placentophagia



Scholarly Articles

Regarding the purpose of placentophagy/placentophagia (consumption of the placenta)
  • Placentophagia: A Biobehavioral Enigma. KRISTAL, M. B. . NEUROSCI. BIOBEHAV. REV. 4(2) 141-150, 1980.

Although ingestion of the afterbirth during delivery is a reliable component of parturitional behavior of mothers in most mammalian species, we know almost nothing of the direct causes or consequences of the act. Traditional explanations of placentophagia, such as general or specific hunger, are discussed and evaluated in light of recent experimental results. Next, research is reviewed which has attempted to distinguish between placentophagia as a maternal behavior and placentophagia as an ingestive behavior. Finally, consequences of the behavior, which may also be viewed as ultimate causes in an evolutionary sense, are considered, such as the possibility of beneficial effects on maternal behavior or reproductive competence, on protection against predators, and on immunological protection afforded either the mother or the young. 

  • The Biopsychology of Maternal Behavior in Nonhuman Mammals. Kristal, M.B. Institute for Laboratory Animal Research: 50 (1): 51-63, 2009.

The term “maternal behavior,” when applied to nonhuman mammals, includes the behaviors exhibited in preparation for the arrival of newborn, in the care and protection of the newly arrived young, and in the weaning of those young, and represents a complex predictable pattern that is often regarded as a single, comprehensive, species-specifi c phenomenon. Although the delivering fi rst-time mammalian mother is immediately and appropriately maternal, a “virgin” with no prior exposure to young does not show immediate and appropriate behavior toward foster young. Nevertheless, the virgin female, and indeed the male, possess the neural circuitry that underlies the pattern referred to as maternal behavior, despite not exhibiting the pattern under normal circumstances. At parturition, or after extensive exposure to young, what emerges appears to be a single stereotyped maternal behavior pattern. However, it is actually a smoothly coordinated constellation of simpler actions with proximate causes that, when sequenced properly, have the appearance of a motivated, purposive, adaptive pattern of caretaking. Over the past 50 years, much research has focused on finding the principal external and internal factors that convert the nonmaternal behavior patterns of the nonpregnant nullipara, the virgin, to the almost immediate and intense maternal behavior characteristic of the puerpera, the mother. This review is an attempt to summarize the many comprehensive, even encyclopedic, reviews of these factors, with an emphasis on brain mechanisms, and to highlight the gaps that remain in understanding the processes involved in the almost immediate onset of maternal caretaking behaviors observed in mammals at delivery. Where possible, the reader is directed to some of those excellent reviews.


Regarding the enhancement of breastmilk production
  • Placenta as Lactagagon. Soykova-Pachnerova, E., et. al.Gynaecologia 138(6):617-627, 1954

An attempt was made to increase milk secretion in mothers by administration of dried placenta per os. Of 210 controlled cases only 29 (13.8%) gave negative results; 181 women (86.2%) reacted positively to the treatment, 117 (55.7%) with good and 64 (30.5%) with very good results. It could be shown by similar experiments with a beef preparation that the effective substance in placenta is not protein. Nor does the lyofilised placenta act as a biogenic stimulator so that the good results of placenta administration cannot be explained as a form of tissue therapy per os. The question of a hormonal influence remains open. So far it could be shown that progesterone is probably not active in increasing lactation after administration of dried placenta. This method of treating hypogalactia seems worth noting since the placenta preparation is easily obtained, has not so far been utilized and in our experience is successful in the majority of women.


Regarding hormone levels
  • Hormonal Changes in the Postpartum and Implications for Postpartum Depression. Hendrick, V., Altshuler, L.L., and Suri, R. Psychosomatics, 39: 93–101. 1998.

The months following childbirth are a time of heightened vulnerability to depressive mood changes. Because of the abrupt and dramatic changes occurring in hormone levels after delivery, many studies have examined the role of hormonal factors in postpartum depression. The authors review the literature on potential hormonal etiologies in postpartum depression, in particular for progesterone, estrogen, prolactin, cortisol, oxytocin, thyroid, and  vasopressin. While evidence for an etiologic role is lacking for most hormones, changes in certain hormonal axes may contribute to depressive mood changes in some women following childbirth.

  • Effects of placentophagy on serum prolactin and progesterone concentrations in rats after parturition or superovulation. Blank MS, Friesen HG.: J Reprod Fertil. 60(2):273-8, 1980

In rats that were allowed to eat the placentae after parturition concentrations of serum prolactin were elevated on Day 1 but concentrations of serum progesterone were depressed on Days 6 and 8 post partum when compared to those of rats prevented from eating the placentae. In rats treated with PMSG to induce superovulation serum prolactin and progesterone values were significantly (P < 0.05) elevated on Days 3 and 5 respectively, after being fed 2 g rat placenta/day for 2 days. However, feeding each rat 4 g placenta/day significantly (P < 0.02) lowered serum progesterone on Day 5. Oestrogen injections or bovine or human placenta in the diet had no effect. The organic phase of a petroleum ether extract of rat placenta (2 g-equivalents/day) lowered peripheral concentrations of progesterone on Day 5, but other extracts were ineffective. We conclude that the rat placenta contains orally-active substance(s) which modify blood levels of pituitary and ovarian hormones. 

  • Hypothalamic corticotropin-releasing hormone suppression during the postpartum period: implications for the increase in psychiatric manifestations at this time. Magiakou et al. The Journal of Clinical Endocrinology and Metabolism, 81 (5): 1912-1917. 1996.

The third trimester of human pregnancy is characterized by a hyperactive hypothalamic-pituitary-adrenal axis, possibly driven by progressively increasing circulating levels of placental CRH and gradually decreasing levels of CRH-binding protein. The postpartum period, on the other hand, is characterized by an increased vulnerability to psychiatric manifestations (postpartum “blues,” depression, and psychosis), a phenomenon compatible with suppressed hypothalamic CRH secretion. To investigate the hypothesis that the postpartum period is associated with suppression of hypothalamic CRH secretion, we studied prospectively 17 healthy euthymic women (mean +/- SE age, 32.0 +/- 1.1 yr) with no prior history of depression, starting at the 20th week of gestation. Psychometric testing was performed monthly during pregnancy and postpartum on day 2 and weeks 2, 3, 6, 8, 12, 16, and 20, whereas serial ovine (o) CRH tests were performed postpartum at 3, 6, and 12 weeks. While pregnant, all 17 subjects remained euthymic; in the postpartum period, 7 women developed the “blues,” and 1 developed depression. Overall, the mean plasma ACTH response to an iv bolus of 1 microgram/kg oCRH was markedly blunted at 3 and 6 weeks, but normal at 12 weeks postpartum, whereas the mean plasma cortisol response was at the upper limit of normal at all 3 times. These data are compatible with a suppressed hypothalamic CRH neuron that gradually returns to normal while hypertropic adrenal cortexes are progressively down-sizing. When the postpartum ACTH responses to oCRH were analyzed separately for the euthymic women and the women who had the “blues” or depression, the blunting of ACTH was significantly more severe and long lasting in the latter group; this was observed at all 3 times of testing. We conclude that there is central suppression of hypothalamic CRH secretion in the postpartum, which might explain the increased vulnerability to the affective disorders observed during this period. The suppressed ACTH response to oCRH might serve as a biochemical marker of the postpartum “blues” or depression.

Regarding the links between iron deficiency, fatigue, and postpartum depression
  • Have we forgotten the significance of postpartum iron deficiency? Bodnar, L.M. et. al.; American Journal of Obstetrics and Gynecology: 193, 36–44, 1995.

The postpartum period is conventionally thought to be the time of lowest iron deficiency risk because iron status is expected to improve dramatically after delivery. Nonetheless, recent studies have reported a high prevalence of postpartum iron deficiency and anemia among ethnically diverse low-income populations in the United States. In light of the recent emergence of this problem in the medical literature, we discuss updated findings on postpartum iron deficiency, including its prevalence, functional consequences, risk factors, and recommended primary and secondary prevention strategies. The productivity and cognitive gains made possible by improving iron nutriture support intervention. We therefore conclude that postpartum iron deficiency warrants greater attention and higher quality care.

  • Maternal Iron Deficiency Anemia Affects Postpartum Emotions and Cognition. Beard, J.L., et. al.; J. Nutr. 135: 267–272, 2005.

The aim of this study was to determine whether iron deficiency anemia (IDA) in mothers alters their maternal cognitive and behavioral performance, the mother-infant interaction, and the infant’s development. This article focuses on the relation between IDA and cognition as well as behavioral affect in the young mothers. This prospective, randomized, controlled, intervention trial was conducted in South Africa among 3 groups of mothers: nonanemic controls and anemic mothers receiving either placebo (10 g folate and 25 mg vitamin C) or daily iron (125 mg FeS04, 10 g folate, 25 mg vitamin C). Mothers of full-term normal birth weight babies were followed from 10 wk to 9 mo postpartum (n 81). Maternal hematologic and iron status, socioeconomic, cognitive, and emotional status, motherinfant interaction, and the development of the infants were assessed at 10 wk and 9 mo postpartum. Behavioral and cognitive variables at baseline did not differ between iron-deficient anemic mothers and nonanemic mothers. However, iron treatment resulted in a 25% improvement (P 0.05) in previously iron-deficient mothers’ depression and stress scales as well as in the Raven’s Progressive Matrices test. Anemic mothers administered placebo did not improve in behavioral measures. Multivariate analysis showed a strong association between iron status variables (hemoglobin, mean corpuscular volume, and transferrin saturation) and cognitive variables (Digit Symbol) as well as behavioral variables (anxiety, stress, depression). This study demonstrates that there is a strong relation between iron status and depression, stress, and cognitive functioning in poor African mothers during the postpartum period. There are likely ramifications of this poorer “functioning” on mother-child interactions and infant development, but the constraints around this relation will have to be defined in larger studies. 

  • Iron content of intact placentas and cords. McCoy, B.A., et al.; The American Journal of Clinical Nutrition. 9: 613-615, 1961.

The only significant iron loss during a normal pregnancy occurs at parturition. In addition to the loss of iron to the infant and as result of hemorrhage, iron contained in placental blood, and in placental and cord tissue, is lost. Values for the blood content of a total of 216 placentas were published by several investigators, and ranged from 9 to 33.4 per cent of the wet weight of the organs. In a study of 143 German women, Mischel found that the total iron in the blood and tissues of the placentas averaged 11.1 and 4.2mg, respectively, per 100gm of wet samples. More information on the iron content of placentas is needed in the evaluation of the iron requirement during pregnancy. The majority of investigations of the problem have been completed outside the United States, and few details of such factors as diet, prenatal medications and delivery procedures are included, all of which may influence placental iron losses. It appeared worthwhile, therefore, to collect intact placentas and their cords from the delivery room of the State University of Iowa Hospitals in order to evaluate this material in maternal iron loss.

  • Iron supplementation for unexplained fatigue in non-anaemic women: double blind randomised placebo controlled trial. Verdon, F., et. al.; BMJ 326:1124 2003.

Objective: To determine the subjective response to iron therapy in non-anaemic women with unexplained fatigue. Design: Double blind randomised placebo controlled trial.Setting: Academic primary care centre and eight general practices in western Switzerland. Participants: 144 women aged 18 to 55, assigned to either oral ferrous sulphate (80 mg/day of elemental iron daily; n=75) or placebo (n=69) for four weeks.Main outcome measures: Level of fatigue, measured by a 10 point visual analogue scale.Results: 136 (94%) women completed the study. Most had a low serum ferritin concentration; ≤ 20 μg/l in 69 (51%) women. Mean age, haemoglobin concentration, serum ferritin concentration, level of fatigue, depression, and anxiety were similar in both groups at baseline. Both groups were also similar for compliance and dropout rates. The level of fatigue after one month decreased by −1.82/6.37 points (29%) in the iron group compared with −0.85/6.46 points (13%) in the placebo group (difference 0.95 points, 95% confidence interval 0.32 to 1.62; P=0.004). Subgroups analysis showed that only women with ferritin concentrations ≤ 50 μg/l improved with oral supplementation. Conclusion: Non-anaemic women with unexplained fatigue may benefit from iron supplementation. The effect may be restricted to women with low or borderline serum ferritin concentrations. 

  • Fatigue as a Predictor of Postpartum Depression. Journal of Obstetric, Gynecologic, & Neonatal Nursing 31 (4), 436-443, 2002.

Background: The postpartum is a time when women commonly report increased fatigue that may contribute to depression. Studies have not examined fatigue alone as a predictor of postpartum depression. Objective: To examine whether and when fatigue in the early postpartum is predictive of postpartum depression. Design: Correlational, longitudinal study. Setting: Two hospitals and participants’ homes in central Pennsylvania. Participants: Convenience sample of 38 healthy women recruited from hospital maternity units within 24 hours after an uncomplicated birth. Main Outcome Measures: Fatigue was measured using the Modified Fatigue Symptom Checklist (MFSC) on Days 0, 7, 14, and 28 after childbirth. Depression was assessed using the Center for Epidemiological Studies-Depressive Symptomatology Scale (CES-D) on Day 28. Results: After adjustments for multiple comparisons, a significant correlation was obtained between fatigue as measured by the MFSC and postpartum depression on Day 7 (r = .46; p < .05), Day 14 (r =.57), and Day 28 (r = .70). Fatigue on Day 0 was correlated with fatigue on Day 7 (r = .45), Day 14 (r =.58), and Day 28 (r = .34).Conclusions: Fatigue as early as 7 days postpartum is predictive of depression at Day 28 postpartum.

  • The Impact of Fatigue on the Development of Postpartum Depression. Corwin, E.J., et. al; Journal of Obstetric, Gynecologic, & Neonatal Nursing 34 (5), 577–586, 2005.

Background: Previous research suggests early postpartum fatigue (PPF) plays a significant role in the development of postpartum depression (PPD). Predicting risk for PPD via early identification of PPF may provide opportunity for intervention. Objective:To replicate and extend previous studies concerning the impact of PPF on symptoms of PPD and to describe the relationships among PPF, PPD, and other variables using the theory of unpleasant symptoms. Design: Correlational, longitudinal study. Setting: Participants’ homes. Participants: Convenience sample of 42 community-dwelling women recruited before 36 weeks of pregnancy. Main Outcome Measures: PPF, depressive symptoms, and stress measured during prenatal weeks 36 to 38, and on Days 7, 14, and 28 after childbirth. Salivary cortisol was measured as a physiological marker of stress. Results: Significant correlations were obtained between PPF and symptoms of PPD on Days 7, 14, and 28, with Day 14 PPF levels predicting future development of PPD symptoms in 10 of 11 women. Perceived stress, but not cortisol, was also correlated with symptoms of PPD on Days 7, 14, and 28. Women with a history of depression had elevated depression scores compared to women without, but no variable was as effective at predicting PPD as PPF. Conclusions: Fatigue by Day 14 postpartum was the most predictive variable for symptoms of PPD on Day 28 in this population. 


Regarding pain relief
  • Placenta ingestion by rats enhances δ- and κ-opioid antinociception, but suppresses μ-opioid antinociception. DiPirro, J.M., Kristal, M.B. Brain Research 1014: 22–33, 2004.

Ingestion of placenta or amniotic fluid produces a dramatic enhancement of centrally mediated opioid antinociception in the rat. The present experiments investigated the role of each opioid receptor type (μ, δ, κ) in the antinociception-modulating effects of Placental Opioid-Enhancing Factor (POEF—presumably the active substance). Antinociception was measured on a 52 jC hotplate in adult, female rats after they ingested placenta or control substance (1.0 g) and after they received an intracerebroventricular injection of a δ-specific ([D-Pen2,D-Pen5]enkephalin (DPDPE); 0, 30, 50, 62, or 70 nmol), μ-specific ([D-Ala2,N-MePhe4,Gly5-ol]enkephalin (DAMGO); 0, 0.21, 0.29, or 0.39 nmol), or κ-specific (U-62066; spiradoline; 0, 100, 150, or 200 nmol) opioid receptor agonist. The results showed that ingestion of placenta potentiated y- and n-opioid antinociception, but attenuated μ-opioid antinociception. This finding of POEF action as both opioid receptor-specific and complex provides an important basis for understanding the intrinsic pain-suppression mechanisms that are activated during parturition and modified by placentophagia, and important information for the possible use of POEF as an adjunct to opioids in pain management. 

  • Enhancement of Opioid-Mediated Analgesia: A Solution to the Enigma of Placentophagia. KRISTAL, M.B. NEUROSCI BIOBEHAV REV 15(3) 425-435, 1991.

Two major consequences of placentophagia, the ingestion of afterbirth materials that occurs usually during mammalian parturition, have been uncovered in the past several years. The first is that increased contact, associated with ingesting placenta and amniotic fluid from the surface of the young, causes an accelerated onset of maternal behavior toward those young. The second, which probably has importance for a broader range of mammalian taxa than the first, is that ingestion of afterbirth materials produces enhancement of  ongoing opioid-mediated analgesia. The active substance in placenta and amniotic fluid has been named POEF, for Placental Opioid-Enhancing Factor. Recent research on both consequences is summarized, with particular attention to POEF, the generalizability of the enhancement phenomenon, its locus and mode of action, and its significance for new approaches to the management of pain and addiction.

  • Participation of placental opioid-enhancing factor in opioid-modulated events at parturition. Kristal MB. 1998.Online Proceedings of the 5thInternet World Congress on Biomedical Sciences ’98 at McMaster University, Ontario, Canada.

Parturition in mammals occurs in the context of sensory, neurochemical, and endocrinological factors that are orchestrated and timed so that maternal behavior and the object of the behavior, the neonate, “emerge” almost simultaneously. Among the factors found to be important for the suppression of pain during delivery as well as for the emergence of caretaking behavior toward the young, are changes in endogenous opioid activity in the central nervous system. In most mammalian species, these changes are likely initiated by sensory events arising in the distended reproductive tract and abdominal musculature, and are modified by the parturitional endocrine milieu and substances ingested in amniotic fluid and placenta (e.g., Placental Opioid-Enhancing Factor, or POEF). In addition, ingestion of afterbirth material may decrease the probability that the vaginal/cervical sensory stimulation arising during delivery will trigger pseudopregnancy, a condition that decreases, if not eliminates, the likelihood of fertilization in the postpartum estrus. The research described herein primarily focuses on elucidating the manner in which POEF modulates opioid antinociception, and otherwise participates in opioid-mediated parturitional events. 


bottom of page