Table 1.

Studies correlations between endogenous levels and postpartum depressive symptoms

						Results
Author, Year	Purpose#	Setting & Sample	Methods	Endogenous Oxytocin Measurement	Mood Measurement	Prenatal	Early Postpartum (≤ 6 weeks)	Late Postpartum (> 6 weeks)	Newcastle-Ottawa quality score*
Cox et al. 2015	To test associations between OT levels during breastfeeding and stress reactivity and quantify the acute effects of lactation on stress response	n= 52 pregnant community women with intention to breast-feed, mixed history of depression, well-educated majority (83%) white same cohort as Stuebe et al. (2013)	Mothers were evaluated for depression and anxiety at 2- and 8-weeks postpartum. They underwent the Trier Social Stress test at 8 weeks postpartum after they either breastfeed or held their infants. Plasma samples were collected during feeding (at baseline, at 1, 3, 7, and 10 minutes of feeding, and postfeed) and at minutes 2 and 4 of the stress test and 10 minutes poststressor.	ELISA (Enzo) Extracted plasma, visits at 1 pm	Clinical interview (SCID-NP) EPDS STAI			Symptomatic breastfeeding mothers (EPDS ≥ 10 and/or STAI ≥34)had lower levels of OT during feedings (p<0.05). In this group, higher OT AUC was associated with higher stress during testing (p < 0.05).	8
Eapen et al. 2014	To explore the associations between pregnancy and early PP OT plasma levels and early maternal attachment experiences, symptoms of separation anxiety, and depression.	n= 57 52% Caucasian, purposefully sampled into “separation anxiety” and “without separation anxiety” groups based on ASA-27	At either 28 or 32 weeks gestation women completed mood measures and gave blood for plasma OT. This was repeated at 3 months postpartum with some additional questionnaires.	Radioimmunoassay Extracted plasma	EPDS, STAI, Adult Separation Anxiety Questionnaire (ASA-27)	No association between plasma OT and EPDS scores		At 3 months lower levels of OT were associated with higher depressive symptoms (p<001)	7
Guintivano et al. 2017	To examine the contributions of genetic ancestry, adverse life events, psychological, and biological factors in the development of PPD	n=1517 Black, Latina, and white women (549 PPD, 968 controls)	Both cases and controls recruitedn from outpatient OB clinics at 6 weeks postpartum where they were screened using EPDS. Participants were assessed for psychiatric disorders and gave plasma and serum for biological assays and genotyping. Depressed defined as EPDS ≥ 11, v not depressed defined as EPDS ≤ 7	ELISA, Extracted plasma,	EPDS, Mini International Neuropsychiatric Interview (MINI-Plus)			OT levels were not significantly associated with PPD between the two groups after controlling for factors that may influence hormone levels such as breastfeeding status, genetic ancestry, maternal age, etc.	7
Jobst et al. 2016	To evaluate the relationship between oxytocin plasma levels during pregnancy and postpartum and presence of depressive symptoms	n=89 healthy community sample	Women were recruited at 34 weeks gestation. Plasma and mood measures were collected at 5 timepoints (35 and 38 weeks gestation, 2 days, 7 weeks and 6 months postpartum.	ELISA (Enzo) Unextracted plasma diluted 1:3 Collected between 8-10 AM	Montgomery-Åsberg Depression Rating Scale (MADRS)	The change in trajectory of OT plasma levels was significantly different between women with and without depressive symptoms. Women in the ‘non-depressed’ group showed continuous increase in OT levels at all timepoints while those in the ‘depressed’ group dropped between late pregnancy and 2 days postpartum; OR .989			6
Lara-Cinisomo et al. 2017	To obtain pilot data exploring associations between PPD, BF practices, and OT response to infant feeding	n=28 Latina women	Mothers assessed at three times: 3rd trimester for demographics and complete psychological assessment, 4 weeks PP by phone-EPDS, bonding and BF; 8 weeks PP in person EPDS, BF status and plasma OT (via IV catheter 10 minutes before, at minutes 3, 7, and 10 during feeding, and 10 minutes after feeding)	EIA (Enzo) Extracted plasma, visits all beginning at 9 AM See above Lara-Cinisomo et al. (2018).	EPDS Postpartum Bonding Questionnaire (PDQ) Clinical interview			At 8 weeks depressed women (EPDS ≥ 10) that were not BF had lower OT AUC than nondepressed, non-BF women (p=0.044).	8
Lara-Cinisomo et al. 2018a	To explore associations between PPD, traumatic life events and maternal/ infant bonding	n=28 Latina women, community sample [same sample as Lara-Cinisomo et al. (2017)]	See above Lara-Cinisomo et al. (2017).	See above Lara-Cinisomo et al. (2017).	See above Lara-Cinisomo et al. (2017).			At 8 weeks women with PPD exhibited non-significantly lower mean plasma OT AUC than those without symptoms	8
Lara-Cinisomo et al. 2018b	To develop a descriptive picture of Latinas’ postnatal depression and OT profiles and to explore associations between maternal mood and OT levels	n=108 sub study (Pedersen et al., 2016) of women that identify as either Hispanic or Latina, community sample from public health prenatal clinic	Women completed home visits at 35-36 weeks of pregnancy and 6 weeks postpartum. Depression and anxiety data and 24-hour participant collected urine samples collected at both visits	ELISA (Enzo) 24-hour urine samples. Extracted samples	EPDS STAI		Women with PPD showed persistently higher mean OT over time. Non-PPD had a significant decrease in OT levels over time (p=.002).		8
Massey et al. 2016	To examine plasma oxytocin concentration and PPD symptom severity and if this might differ by lifetime history of major depressive disorder (MDD)	n= 66 low risk, community sample without prenatal depression, majority (73%) Caucasian	Women in the third trimester of pregnancy were assessed for current mood disorders and gave plasma OT samples. 6 weeks PP participants were assed (primarily via telephone) for birth outcomes and depressive symptoms/ severity	ELISA (Enzo) Unextracted plasma diluted 1:8	MINI Mood Disorders Questionnaire Inventory of Depressive Symptomatology (IDS-SR30) EPDS	Positive relationship between third trimester OT and PPD symptom severity (p=.019) only in women with a history of MDD			8
Samuel et al. 2015	To investigate if levels of OT in mothers with mood or anxiety disorders differ from mentally healthy controls and if maternal mental health moderates the relationship between OT levels and interactive behavior.	n= 110 20 in “clinical sample” with a clinically diagnosed mood or anxiety disorder, 90 postpartum in comparison group scoring low for depressive symptoms	At 2 months PP every mother/ infant dyad was assessed in home. Blood was drawn for serum OT and mothers were filmed (and later coded) interacting with infant.	ELISA (Enzo) Unextracted plasma diluted 1:2 or 1:4	EPDS Global Rating Scale of Depression (GRS)			No group differences in OT levels However, in the clinical sample, higher OT levels were associated with less depressive behavior (p≤.01).	7
Skrundz et al. 2011	To explore the relationship between plasma OT levels prenatally and the development of PPD symptoms.	n=74 healthy women	Plasma OT and depressive symptoms were assessed between 30-34 weeks gestation. At 2 weeks PP, the EPDS was repeated. Other birth variables were collected by chart review.	Radioimmunoassay Plasma	EPDS	No significant associations between prenatal EPDS and OT levels.	Lower OT level mid pregnancy predicted higher EPDS at 2 weeks postpartum (p<0.05).		6
Stuebe et al. 2013	To explore the relationship between maternal mood and neuroendocrine response to breast feeding	n=47 pregnant community women with intention to breast-feed, mixed history of depression, welleducated majority (83%) white same cohort as Cox et al.	EPDS and STAI as well as assessment by a psychiatrist and blood sample for plasma OT in the 3rd trimester. At 2 and 8 weeks postpartum the EPDS and STAI were repeated and plasma OT was measured at baseline, 1, 4, 7, and 10 minutes of feeding, and postfeed.	EIA (Enzo) Extracted plasma	Clinical interview EPDS STAI	Third-trimester plasma OT were inversely correlated with EPDS scores (p=0.03)	A two weeks baseline OT was inversely correlated with EPDS scores (p=0.03).	At eight weeks EPDS were inversely correlated with OT AUC during feedings (p<0.01)	8
Zelkowitz et al. 2014	To investigate the relationship of psychosocial stress, PPD symptoms and maternal sensitive behavior to endogenous OT levels	n=287 well educated, community sample	Women were assessed at three time points (12–14 weeks and 32–34 weeks gestation, and 7–9 weeks PP) At each point, participants completed psychosocial measures and gave blood.	ELISA (Enzo) Unextracted plasma diluted 1:2 or 1:3	EPDS Antenatal Risk Questionnaire (ANRQ)	At 12-14 weeks in mothers with high stress, higher OT was associated with lower depressive symptoms (p<0.05).		At 7-9 weeks in mothers with high stress, higher levels of OT were associated with lower depressive symptoms (p<0.001).	6

^*0-2: low quality, 3-5: moderate quality, 6-8: high quality

^#purpose as defined in primary study

PPD= postpartum depression; OT= oxytocin; BF= breastfeeding; EPDS= Edinburgh Postnatal Depression Scale; SCID-NP= Structured Clinical Interview for the DSMIV (Diagnostic and Statistical Manual of Mental Disorders); STAI= State Trait Anxiety Inventory; ELISA= enzyme-linked immunosorbent assay; AUC= area under the curve