You will be presented with a collection of medical randomized controlled trial (RCT) reports addressing a shared clinical question -- for instance, the efficacy of a medical intervention on a disease or condition. Given the titles and abstracts of these reports, your task is to generate the conclusion of the systematic review article synthesizing the key findings. Your conclusion should be a few sentences long. In your response, include only the conclusion and no other text. The RCT reports are below.



Title 1:
Naturally occurring variations in maternal behavior in the rat are associated with differences in estrogen-inducible central oxytocin receptors
Abstract 1:
Naturally occurring variations in maternal licking/grooming influence neural development and are transmitted from mother to female offspring . We found that the induction of maternal behavior in virgin females through constant exposure to pups ( pup sensitization ) was significantly shorter in the offspring of High compared with Low licking/grooming mothers , suggesting differences in maternal responsivity . In r and omly selected females screened for individual differences in maternal responsivity and subsequently mated , there was a significant and negative correlation ( r = −0.73 ) between the latency to exhibit maternal behavior in the pup sensitization paradigm and the frequency of pup licking/grooming during lactation . Females that were more maternally responsive to pups and that showed increased levels of pup licking/grooming also showed significantly higher oxytocin receptor levels in the medial preoptic area , the lateral septum , the central nucleus ( n. ) of the amygdala , the paraventricular n. of the hypothalamus , and the bed n. of the stria terminalis . Intracerebroventricular administration of an oxytocin receptor antagonist to mothers on postpartum day 3 completely eliminated the differences in pup licking/grooming , suggesting that differences in oxytocin receptor levels are functionally related to maternal behavior . Finally , estrogen treatment of virgin females significantly increased oxytocin receptor binding in the medial preoptic area and lateral septum of female offspring of High , but not Low , licking/grooming mothers . These findings suggest that maternal licking/grooming influences the development of estrogen sensitivity in brain regions that regulate maternal behavior , providing a potential mechanism for the intergenerational transmission of individual differences in maternal behavior


Title 2:
Physiological Regulation of Maternal Behavior in Heifers: Roles of Genital Stimulation, Intracerebral Oxytocin Release, and Ovarian Steroids1
Abstract 2:
Abstract We tested the hypotheses that 1 ) epidural anesthesia at parturition would block both peripheral and central release of oxytocin and eliminate the development of maternal behavior in primiparous heifers and 2 ) estradiol priming , genital stimulation , and appropriate neonatal stimuli would induce maternal behavior in nulliparous heifers . In experiment 1 , primiparous crossbred heifers ( n = 13 ) with cannulas in the third cerebroventricle ( IIIV ) were assigned r and omly to receive epidural treatments of saline ( SAL ; n = 6 ) or lidocaine HCl ( EPI ; n = 7 ) at the onset of labor induced between Days 270 and 280 of gestation . Epidural anesthesia blocked ( P < 0.001 ) both central and peripheral release of oxytocin and markedly reduced ( P < 0.05 ) or eliminated licking behaviors during a 3-h period following parturition as compared with SAL . Following approximately 1 wk of controlled daily suckling , during which calves were permitted access only to the inguinal region of their dams ( three times daily for 10 min each time ) , a second maternal behavior test was performed . Although licking behavior remained markedly reduced ( P < 0.001 ) in the EPI compared with the SAL groups , all heifers accepted their calf at the udder . In experiments 2–4 , neither estradiol priming in ovariectomized heifers nor estradiol plus progesterone in intact heifers result ed in an induction of maternal behaviors following genital stimulation and presentation of a neonate wetted with amniotic fluid . Pelvic sensory deficits apparently block oxytocin release and disturb both short-latency and long-term maternal behaviors but do not result ultimately in rejection of the calf . Combinations of hormonal , sensory , olfactory , and visual cues observed previously to induce maternal behavior in nulliparous ewes do not appear adequate for induction of maternal behavior in nulliparous heifers


Title 3:
Oxytocin is associated with human trustworthiness
Abstract 3:
Human beings exhibit substantial interpersonal trust-even with strangers . The neuroactive hormone oxytocin facilitates social recognition in animals , and we examine if oxytocin is related to trustworthiness between humans . This paper reports the results of an experiment to test this hypothesis , where trust and trustworthiness are measured using the sequential anonymous " trust game " with monetary payoffs . We find that oxytocin levels are higher in subjects who receive a monetary transfer that reflects an intention of trust relative to an unintentional monetary transfer of the same amount . In addition , higher oxytocin levels are associated with trustworthy behavior ( the reciprocation of trust ) . Absent intentionality , both the oxytocin and behavioral responses are extinguished . We conclude that perceptions of intentions of trust affect levels of circulating oxytocin


Title 4:
Experiential and hormonal correlates of maternal behavior in teen and adult mothers
Abstract 4:
This study explores the role of cortisol and early life experiences in the regulation of maternal behavior and mood in teen and adult mothers . Primiparous mothers ( n=119 ) ( teen mothers < 19 years , n=42 ) , young mothers ( 19 - 25 years , n= 4 ) , and mature mothers , ( > 25 years , n=43 ) were assessed for their maternal behavior , mood , and hormonal profile at approximately 6 weeks postpartum . Outcome measures were analyzed as a function of age and early life experience . Results showed an interaction between age and type of maternal behavior , where teen mothers engaged in more instrumental ( e.g. changing diapers , adjusting clothes ) less affectionate ( e.g. , stroking , kissing , patting ) behavior , and mature mothers engaged in more affectionate and less instrumental behavior . When groups were reassessed based on early life experience ( consistency of care during the first 12 years of life : consistent care ; having at least one consistent caregiver , inconsistent care ; having multiple and changing caregivers ) , an interaction was also found between consistency of care and type of behavior shown , where mothers who received inconsistent care engaged in more instrumental and less affectionate behavior . Compared to mature mothers , teen mothers who were breast feeding also had higher salivary cortisol levels , and high cortisol in teen mothers related to decreased fatigue and increased energy . These results suggest that early life experiences are linked to mothering behavior and are consistent with the emerging human and animal literature on intergenerational effects of mothering style


Title 5:
Intranasal oxytocin increases fathers’ observed responsiveness during play with their children: A double-blind within-subject experiment
Abstract 5:
Recent correlational studies showed that oxytocin is associated with parenting style in humans as in other mammals . Here the first double-blind , placebo-controlled , within-subject experiment with intranasal oxytocin administration is presented . Subjects were 17 fathers with their toddler , observed in two play sessions of 15 min each with an intervening period of 1 week . In the oxytocin condition fathers were more stimulating of their child 's exploration than in the placebo condition , and they tended to show less hostility . Parent training experiments might be combined with intranasal oxytocin administration to test differential and cumulative effects of traditional , interaction-focused versus pharmaceutical treatments


Title 6:
Oxytocin responsivity in mothers of infants: a preliminary study of relationships with blood pressure during laboratory stress and normal ambulatory activity.
Abstract 6:
The neuropeptide oxytocin ( OT ) enhances maternal behavior and decreases blood pressure ( BP ) and stress responses in animals . Thus , the relationship of OT responsivity to BP in 14 breast- and 11 bottle-feeding mothers of infants was examined . Laboratory BP was assessed during baseline , speech preparation , active speech , and recovery on 2 days , 1 in which baseline and speech were separated by 10 min of baby holding and the other by no baby contact .  Systolic BP reactivity to speech was lower after baby contact . Plasma OT change from baseline to speech after baby contact defined OT increase , minimal OT change , and OT decrease groups . OT increase mothers were primarily breast-feeders , and they had lower BP throughout both stress sessions and after baby feeding at home than OT decrease mothers , who also had greater BP reactivity to preparation and recovery . These results suggest that oxytocin has antistress and BP-lowering effects in humans


Title 7:
Breast-feeding is associated with reduced perceived stress and negative mood in mothers.
Abstract 7:
Two studies examined the effects of  breast-feeding  on  maternal stress and mood .  In Experiment 1 , perceived stress in the past month was compared between 28 breast-feeding and 27 bottle-feeding mothers . Breast-feeding mothers reported less perceived stress , after controlling for demographic confounds . In Experiment 2 , mood ratings were assessed in the same 24 mothers both before and then after 1 breast-feeding and 1 bottle-feeding session . Breast-feeding was associated with a decrease in negative mood , and bottle-feeding was associated with a decrease in positive mood from pre- to postfeeding . Results indicated that breast-feeding buffers negative mood . These effects appeared to be attributable to the effects of breast-feeding itself and not solely to individual-differences factors


Title 8:
The effect of a supportive companion on perinatal problems, length of labor, and mother-infant interaction.
Abstract 8:
We studied the effects of a supportive lay woman ( " doula " ) on the length of labor and on mother-infant interaction after delivery in healthy Guatemalan primigravid women . Initial assignment of mothers to the experimental ( doula ) or control group was r and om , but controls showed a higher rate ( P less than 0.001 ) of subsequent perinatal problems ( e.g. cesarean section and meconium staining ) . It was necessary to admit 103 mothers to the control group and 33 to the experimental group to obtain 20 in each group with uncomplicated deliveries . In the final sample , the length of time from admission to delivery was shorter in the experimental group ( 8.8 vs. 19.3 hours , P less than 0.001 ) . Mothers who had a doula present during labor were awake more after delivery ( P less than 0.02 ) and stroked ( P less than 0.001 ) , smiled at ( P less than 0.009 ) , and talked to ( P less than 0.002 ) their babies more than the control mothers . These observations suggest that there may be major perinatal benefits of constant human support during labor
CONCLUSIONS Oxytocin appears to be of crucial importance for underst and ing mother-infant relationships .
Research that draws on more robust measures of attachment and bonding , as well as improved measures of  oxytocin  that include both central and peripheral levels , will eluci date the role of oxytocin in human mother-infant relationships .