ORIGINAL ARTICLE

Married With Children: The Influence of Parental Statusand Gender on Ambulatory Blood Pressure

Julianne Holt-Lunstad, Ph.D. &Wendy Birmingham, M.S. & Adam M. Howard, B.S. &Dustin Thoman, Ph.D.

# The Society of Behavioral Medicine 2010

AbstractBackground Although there is substantial evidence thatsocial relationships and marriage may influence bothpsychological and physical health, little is known aboutthe influence of children.Purpose This study examined the competing predictionsregarding the directional influence of parental status and itsinteraction with gender—given that mothers are typicallydisproportionately more responsible for everyday care ofchildren—on cardiovascular functioning.Method We examined ambulatory blood pressure (ABP)over 24 hours among 198 married males and females.Results Couples without children had significantly higherambulatory SBP and DBP than those with children.Moreover, we found a significant interaction betweenparental status and gender that suggested women withchildren showed the lowest ABP, whereas women withoutchildren displayed the highest ABP.Conclusion These findings suggest that parenthood, andespecially motherhood, may be cardioprotective.

Keywords Ambulatory blood pressure . Parental status .

Marriage . Children . Stress . Cardiovascular

Introduction

First comes love, then comes marriage, then comesthe baby in the baby carriage.

Although this may or may not be the ideal for manyadults, or come in this order (or at all), most of us arefamiliar with this cultural norm. Psychologists have a richhistory of research examining love and social relationships,with a growing body of research examining marriage;however, we know very little about the addition of “thebaby in the baby carriage.” For many adults, marriage andchildren play a significant role in their social lives. Whilethere is a substantial literature documenting the associationbetween social relationships and health [1], and even asignificant body of literature devoted specifically to themarital relationship [2], whether or not children influencethe physical health of parents is unclear. There is, however,reason to believe that children would be influential, but it isunclear from current evidence whether the effect would bepositive or negative.

Parenting is certainly associated with very polarizedimages. There are images of snuggling babies, playing atthe park, and the more general emotional joy andsatisfaction that are associated with children. On the otherhand, there are images of frustration (e.g., tantrums,whining, crying) and constant caregiving (e.g., feeding,changing, cleaning) that may be taxing. Similarly, relevantresearch also appears mixed with findings documentingdetrimental effects associated with caregiving [3, 4],whereas provision of support is associated with healthbenefits [5, 6]. So the question remains, do we benefit

J. Holt-Lunstad (*)Department of Psychology, Brigham Young University,1024 Spencer W. Kimball Tower,Provo, UT 84020, USAe-mail: julianne.holt-lunstad@byu.edu

W. BirminghamDepartment of Psychology, University of Utah,Salt Lake City, Utah, USA

A. M. HowardSchool of Medicine, University of Utah,Salt Lake City, Utah, USA

D. ThomanDepartment of Psychology, California State University,Long Beach, CA, USA

ann. behav. med.DOI 10.1007/s12160-009-9152-1

physiologically from the positive aspects of parenthood orare the challenges of parenting deleterious? Currently littleis known about the effect of parental status on thephysiological processes that inform health; thus it is unclearwhether having children may impact the health of parents,and if so in what direction.

The Negative Side

The potential for a deleterious influence of parenthood canbe seen across several different literatures. For example, ameta-analysis of the effect of children on marital qualityconcluded that marital quality decreased with the birth ofthe first child [7]. Given that marital quality has beenclosely linked with morbidity and mortality [2, 8], it ispossible that children may influence physical health in thisway. Research that has examined the direct influence ofcaregiving also implies that parenting may have a detri-mental influence on health, as caregiving has beenidentified as a major strain on health [9]. For instance,frequent caregiving has been associated with lower emo-tional and financial well-being and less time for socialactivities [10] and lower life satisfaction [11] amongcaregivers. In addition, caregiving has been linked withchronic stress-induced immune dysregulation, such thatcaregivers have poorer responses to vaccines, impairedcontrol of latent viruses, exaggerated production of inflam-matory mediators, and accelerated cellular aging comparedto non-caregivers [12, 13]. Caregiving has also been linkedprospectively to an increased risk for cardiovascular disease[14]. Yet much of what is known about the influence ofcaregiving has focused on caring for the elderly, particu-larly those with a challenging debilitating condition such asdementia, and it is likely that stress associated with caringfor children may be quite different (both qualitatively andperhaps in amount) than caring for debilitated elderlyfamily members.

The level of care associated with raising children maypossibly be more analogous to the influence of dailyhassles, the repetitively frustrating and distressing demandsof everyday life. The cumulative effects of daily hasslesinfluence both mental and physical health outcomes [15].Such hassles are thought to characterize daily interactionswith children, posing a normative stressor for parents andsubsequently influencing overall parental well-being [16].One of the few studies to date to demonstrate an effect ofparental status on blood pressure (BP) found that, amongAfrican Americans, parents have blunted nocturnal DBPdipping compared to non-parents [17]. However, becausethe focus of Iturate’s study was on sleep patterns anddipping it is unclear whether results adequately representthe physiological influence of parenthood or if parentalstatus was a proxy for disrupted sleep patterns.

The Positive Side

Alternatively, there is also evidence to suggest thatparenting may be beneficial. As demonstrated by Lightand colleagues, breast-feeding mothers showed lowersystolic blood pressure (SBP) reactivity to a stressor aftercontact with their baby versus the no-baby-contact controlgroup [18]. According to a meta-analytic review, there wasan overall beneficial effect of fatherhood on men’s self-reported health [19]. In addition, a study examiningdecreases in BP between the workday and evening foundthis effect was greatest in parents [20].

While caring for children may include daily hassles,deriving a sense of meaning and purpose from life stressorshas been shown to be associated with better healthoutcomes [21], and the same may be true for couples withchildren. Among women who gave support in their intimaterelationships, even if that support was not reciprocated(and certainly parental support may not always bereciprocated by children), their subsequent health statusbenefited [22]. Other research demonstrates giving toothers was associated with higher self-esteem and self-efficacy, and lower depression, stress, and physical symp-toms of illness [23–25]. The experience of being importantto another leads to less depression in both men and womenas levels of “mattering” to another increased [26]. Addi-tionally, women experienced less depression than men astheir levels of “mattering” increased. Despite prior findingsof an adverse influence of caregiving on caregivers, otherresearch has begun to disentangle the stress and sense offulfillment associated with providing care to a loved one.As such, caregiving behavior toward a spouse wasassociated with decreased mortality [6]. Given that amongnational samples couples consistently rate children as a toppriority in their marriage [27], parental status may similarlydemonstrate physical benefits of caregiving associated withrole fulfillment.

Aims and Purpose

We examined the competing predictions regarding theinfluence of having children on couples’ ambulatory bloodpressure (ABP). Because ABP is sensitive to both stressorsand support, and studies suggest that elevated ABP is astrong predictor of cardiovascular outcomes [28, 29], it iswell suited to test the influence of parental status oncardiovascular risk. More specifically, we examined thefollowing questions: Do the stressors inherent in theparental role adversely affect health by raising ABP or dothe benefits of parenting lead to better health by decreasingABP? If parental status does matter, does it influence menand women similarly, or will it influence women to agreater extent due to societal gender norms associated with

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parenthood? Does it depend on how many children acouple has, or the age of the child(ren)?

Method

Participants & Procedures

Participants were recruited from the community as part of alarger study focused on marriage (see [30]). Participants(N=202) were reviewed for parental status; however, fourdid not respond to any questions pertaining to parentalstatus, resulting in a total of 198 participants, or 99 couplesages 20–68 (M=31.16, SD=10.39). Consistent with priorresearch (e.g., [31]), the following self-reported inclusioncriteria were used to select healthy participants: no existinghypertension, no cardiovascular prescription medicationuse, no past history of chronic disease with a cardiovascular(e.g., diabetes) or immune (e.g., cancer) component, and norecent history of psychological disorder (e.g., majordepressive disorder). Participants were also excluded ifpregnant. Qualified participants came to the lab to completea packet of questionnaires and have the ABP monitorplaced on them. For validation purposes, a minimum ofthree readings from the ambulatory monitor were comparedagainst a sphygmomanometer using a T-tube adapter.Readings were considered valid if three consecutive read-ings matched (±5 mmHg). Participants left the lab and wereinstructed to go about their normal activities while wearingthe monitor throughout the day and night outside the lab.They returned 24-hours later.

Ambulatory Blood Pressure

Cardiovascular functioning was measured using ambulatory(portable) blood pressure techniques. The Accutracker II(Suntech Medical Instruments, Raleigh, NC) was used toestimate ambulatory readings of systolic (SBP) and diastol-ic (DBP) blood pressure using the auscultatory method. TheAccutraker II was designed specifically for ambulatoryassessments and is well-validated, as readings correspondwith intra-arterial BP assessments during rest, isometricexercise, and bicycle exercise [32]. The monitor was set torandomly take three readings per hour during the day andonce per hour during the night. Based on prior research[33], we deleted readings according to established criteriaindicating artifactual readings.

Monitoring ABP across 24-hours allows for analyses of24-hour BP load and ABP patterns [34]. Because BPfluctuates over 24-hours in a diurnal manner, BP istypically higher during the day than the night [35]. Thus,we examined 24-hour ABP, an average of all readings; aswell as daytime ABP, an average across the readings during

daytime hours (6 am-11 pm); and night-time ABP, anaverage across the readings during nighttime hours(11 pm-6 am). Finally, to assess potential disruptions incircadian rhythm we examined nocturnal BP dipping.Typically BP decreases (or dips) by 10-20% during thenight; however, blunted or non-dipping (<10%) can occurand has been linked to cardiovascular and all-causemortality [36–38]. Dipping was determined by calculatinga change score, taking the average of the BP readingstaken during the day and subtracting the average of thenight-time readings. Thus, higher scores indicate moredipping. The prognostic value of 24-hour ABP monitoringover clinic BP is well documented, but the relativeimportance of daytime, night-time and dipping may varyby disease outcome (see [39–41]).

Self-report Questionnaires

Participants completed a packet of questionnaires thatassessed demographics and mental health. To assess maritalquality we used the satisfaction subscale of the DyadicAdjustment Scale (DAS; [42]), which demonstrated ade-quate reliability (α=.79) within this study. We alsoadministered the Center for Epidemiological Studies De-pression Scale (CES-D; [43]), Satisfaction With Life Scale(SWL; [44]), and the Perceived Stress Scale (PSS; [45]).Each of these measures is widely used and validated withinthe literature and demonstrated high internal consistency(i.e., α=.85, α=.88, and α=.85, respectively) within thisstudy. Participants completed the Pittsburgh Sleep QualityInventory (PSQI), a standard self-report measure thatassesses sleep quality, latency, duration, efficiency, anddisturbances over the past month. The PSQI has been foundto have good internal consistency, test-retest reliability, andvalidity [46]. Participants also rated their sleep quality onthe night of assessment compared to an ordinary night on a1–5 point scale (1 = much worse than usual, 5 = muchbetter than usual).

Statistical Analysis

For our primary analyses we used Proc Mixed (SASInstitute; [47]) to estimate random intercept models withrandom effects for couples. As such, analyses directly modelthe interdependence of husbands’ and wives’ data. Separateanalyses were used to examine the association betweenparental status, gender, and the statistical interaction betweenparental status and gender, for each ABP outcome (24-hour,daytime, nighttime, and dipping of SBP and DBP). Weidentified factors known to contribute independently to BPthat could potentially confound the results and entered theminto the model; thus, we statistically controlled for age, BMI,

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ethnicity, and phase of menstrual cycle. Data are reported asun-standardized regression coefficients. All analyses (includ-ing follow-up analyses) were two-tailed in order to test forboth directional possibilities.

Results

Preliminary Analyses

Sample characteristics are presented in Table 1. Couples weremarried an average of 8.13 years with a range from 1 to42 years. Approximately 70% (n=138 or 69 couples) of thesample had children. The average number of children was1.91 and the ages of the children ranged from less than a yearto 40 years old. Parents were married an average of 2.63 years(range 0–14 years) before the birth of their first child.

We next examined whether parents and non-parentsdiffered on any additional variables that might potentiallyconfound our results. We found that parents were marriedsignificantly longer than non-parents (F(1,192)=34.05;p<.001). Thus, we added the number of years married asan additional covariate in our analyses. Because parentalstatus may be linked to differential lifestyle factors we nexttested whether parents vs. non-parents differed in exercise,smoking, and alcohol consumption. We found no signifi-cant effect of parental status on number of hours spentexercising each week, smoking, or alcohol consumption(ps>.20); nor was there an interaction with gender (p>.20).

Primary Analyses

Does Parental Status Influence Ambulatory Blood Pressure?

We found a significant effect for parental status on 24-hourSBP (F(1,92)=9.85; p<.05; C.I.=2.4–9.95) and DBP(F(1,92)=5.29; p<.05; C.I.=0.42–5.71) such that thosewithout children had significantly higher SBP and DBP thanparents (see Fig. 1). This effect was consistent for daytimeSBP (F(1,92)=7.38; p<.01) and DBP (F(1,92)=5.07;p<.05); however, it was only marginally significant fornight-time SBP (F(1,92)=3.56; p=.06) and did not reachsignificance for night-time DBP (F(1,92)=2.47; p=.11).There was no significant main effect of parental status onnocturnal dipping of SBP or DBP.

Is the Effect of Being a Mother Different than Being a Father?

To examine this question we tested the statistical interactionbetween parental status and gender for our dependentmeasures. While there was no main effect of gender for24-hour SBP or DBP (ps>.05), we did find a significantinteraction between gender and parental status for 24-hour

SBP (F(1,70)=14.60; p<.001) and DBP (F(1,70)=14.89;p<.001). The simple effects of parental status were significantamong women for both SBP (b=11.69; p<.0001; C.I.=6.86–16.51) and DBP (b=7.22; p<.0001; C.I.=3.82–10.62) butnot for men (p>.05). As seen in Fig. 2, females with childrenhad the lowest ambulatory SBP and females without childrenhad the highest DBP. This interaction effect was consistent fordaytime SBP (F(1,79)=8.50; p<.01) and DBP (F(1,79)=13.35; p<.001) and night-time SBP (F(1,69)=11.04;p=.001) and DBP (F(1,70)=7.79; p<.01), and the patternof simple effects tests mirrored those for the 24-hourmeasures.

Similarly, although there was no main effect of parentalstatus on ABP dipping, a significant interaction emergedbetween gender and parental status for SBP dipping(F(1,62)=4.26 ; p<.05), such that women without childrendisplayed the lowest nocturnal dipping (see Fig. 3). Thesimple effects reveal women without children had significant-ly lower (blunted) SBP dipping relative to men withoutchildren (F(1,46)=5.18; p=.02), and marginally lowerrelative to women with children (F(1,46)=3.05; p=.08).There were no other significant effects for nocturnal dipping.

Follow-up Analyses

In an effort to clarify our findings we performed a series offollow-up analyses. Follow-up analyses were performedacross 24-hour ABP and ABP patterns (daytime, night-timeand dipping) for both SBP and DBP. Results from follow-up analyses were generally consistent across the differentABP patterns; thus, in the interest of brevity we only reportanalyses on 24-hour ABP.

Number of Children

We repeated our primary analyses substituting the categoricalvariable of parental status (1 = yes; 0 = no) with a continuousvariable, the number of children.1 We found no effect of thenumber of children, or interaction between number ofchildren and gender, for 24-hour SBP and DBP (ps>.05).Similarly, when we used the number of children as acovariate this did not significantly alter any of our findings.

Does the Effect of Parenthood Differ According to Stageof Parenting?

Presumably some stages of parenting may be more difficultthan others. To test this assumption we examined whetherour effect of parental status held true for parents of babies

1 One couple had 15 children (a blended family). Because this was clearlyan outlier, we repeated our analyses deleting this couple’s data and noneof our findings were altered in significance from what is reported.

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(<2 years old; n=65), teenagers (12–18 years old; n=23), oradult children (>18 years old; n=25). In each case, a separatecategorical variable was used in the analyses.2 Amongparents, we found no significant difference among thosewith babies and those without for 24-hour SBP and DBP(ps>.10). Similarly, we found no significant differencebetween parents with teenagers and parents without for24-hour SBP and DBP (ps>.10). Again, we found nosignificant difference between parents with adult childrenand parents without for 24-hour SBP and DBP (ps>.10).Therefore, the stage of parenting does not appear to have asignificant influence on ABP.

Sleep

Because parents may have differential sleep patterns thannon-parents (e.g., parents of infants may have moredisrupted sleep, parents may go to bed earlier than non-parents) we performed follow-up analyses accounting forthe effect of sleep quality and number of hours slept.Statistically controlling for both sleep quality (as measuredby the Pittsburgh Sleep Quality Index and diary rating forthe night of assessment) and amount of sleep did notsignificantly change our findings.

Work

Because the effect of parental status appears most salientamong women, we examined whether parental status wasinstead a proxy for some other variable such as employ-ment status (i.e., the possibility that women withoutchildren may be more likely to be working outside thehome than women with children). Among our femaleparticipants, 47% were employed either part-time or full-time (classified as “working”). The remaining 53% wereclassified as “non-working” (self-identified as unemployed,retired, homemaker, or student)3. Statistically controllingfor employment status did not significantly change ourfindings for 24-hour SBP or DBP. Thus, the effect ofparental status and the statistical interaction with genderwere independent of the effects of employment.

Psychological Factors

We next examined whether parental status may be linked torelevant psychological factors that might potentially explainour findings. Specifically, we tested for the effect of

2 There were four couples that had both a teen and adult child. Thus,there was a low frequency of overlapping cases.

3 Because the role of student takes one out of the home, we repeated ouranalyses including “student” in the “working” classification. Regardlessof whether student was part of the “working” or “non-working”classification, the effect of parental status and the statistical interactionwith gender were independent of the effects of employment.

Total Sample N=198 Parents n=138 Non-Parents n=60

Age (years) 31.64 (10.39) 33.87 (11.48) 26.54(4.40)

Education (years) 16.43 (2.36) 16.47 (2.54) 16.30(1.89)

Ethnicity (% White) 80.6% 88.4% 64.4%

Years Married 8.13 (9.97) 10.69 (10.85) 2.09 (1.79)

Number of Children 1.92 (2.13) 2.74 (2.05) 0 (0)

Percent employed 58% 52% 74.5%

BMI 25.07 (4.45) 25.41 (4.57) 24.44 (4.22)

Hours of physical activity (per week) 0.65(1.38) 0.54 (1.18) 0.88 (1.73)

Psychological Measures

Marital Satisfaction 19.82 (2.30) 19.78 (2.31) 19.89 (2.28)

Satisfaction with life 20.92 (5.11) 21.71 (4.60) 21.58 (4.84)

Perceived stress 16.16 (5.76) 16.22 (5.33) 16.26 (6.26)

Depression 34.98 (4.25) 35.03 (4.53) 34.70 (3.88)

SBP mmHg

Daytime 118.46 (10.91) 117.93 (11.50) 122.59 (10.43)

24-hour 117.10 (11.06) 115.81 (11.03) 120.36 (10.68)

Dipping 10.33 (9.73) 10.78 (9.80) 11.70 (11.26)

DBP mmHg

Daytime 72.64 (6.87) 72.67 (7.41) 74.63 (6.98)

24-hour 71.43 (7.07) 70.96 (7.03) 72.86 (7.28)

Dipping 8.36 (7.25) 9.05 (6.38) 8.59 (9.54)

Table 1 Sample characteristicsof total sample and by parentalstatus, presented in un-adjustedmeans (standard deviations) orpercentages

BMI = body mass index;SBP = systolic blood pressure;DBP = diastolic blood pressure

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parental status on level of stress, marital satisfaction, lifesatisfaction, and depression. We found no significantdifferences between parents and non-parents on any of ourpsychological measures (p>.20). We further examinedwhether marital satisfaction might moderate our findings.We repeated our previous analysis including maritalsatisfaction. We found no significant interaction effect ofmarital satisfaction and parental status for 24-hour SBP orDBP (p>.20); however, there was a significant three-wayinteraction between gender, parental status, and maritalsatisfaction (b=1.65; p<.05) on 24-hour SBP and a trendfor DBP (b=0.89; p=07). Plots reveal that among coupleswith children, gender discrepancies are greatest at lowlevels of marital satisfaction and virtually disappear at highlevels of satisfaction, compared to couples without children(see Fig. 4). It should be noted that regardless of parentalstatus, men showed a trend of lower ABP associated withhigher marital satisfaction that approximated women with

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children. However, ABP among women without childrenremained high even at high levels of marital satisfaction.

Discussion

The primary aim of this study was to determine whetherparental status has an influence on ABP and if so, in whatdirection. We were also particularly interested in whetherwomen, who typically play a larger role in child-rearing,would have larger differences in ABP than men. Across a24-hour period, we found significantly lower SBP and DBPamong parents than non-parents corresponding to a 6 pointdifference in SBP and a 3 point difference in DBP, and thiswas particularly true for daytime ABP (when most socialinteraction occurs). However, the effect of parental statusappears most salient among women—with the lowest ABPamong mothers and the highest among non-mothers. Thisdifference corresponds to nearly a 12-point difference in24-hour SBP and a 7-point difference in DBP betweenwomen with and without children, and this interactionbetween gender and parental status was reliable for bothdaytime and nighttime measures of ABP. Further, thisinteraction effect also emerged for nocturnal dipping.Among women without children, there was evidence ofSBP non-dipping—a classification used to describe noctur-nal BP decreases less than 10% [48]. Both elevated 24-hourABP and non-dipping have been linked to increasedcardiovascular morbidity and mortality [36–41]. Thus,results in this study generally converge to illustrate positiveeffects of parenthood, particularly for women. Even when afew tests did not reach statistical significance the directionof the effects was always consistent, and no results were inthe opposite direction (either significant or not).

The effect of parental status on ABP also appears to bereliable, as a number of potential alternative explanationsfor this effect were ruled out. The effect of parental statuswas independent of the effect of age, ethnicity, number ofyears married, years married before the birth of the firstchild, and maternal employment status. This effect alsoappears to be consistent across various stages of parenting.This effect of children on cardiovascular activity alsoappears to be a threshold effect rather than a gradienteffect, as parental status was a better predictor of ABP thannumber of children.

Additionally, we found no significant difference betweenparents and non-parents on a number of psychologicalfactors. Although relevant literature suggests children mayinfluence stress and marital quality [7, 49], our resultssuggest that there were no difference between parents andnon-parents on levels of stress; however, it is possible thatparents and non-parents may have different types ofstressors not assessed by our measures. Interestingly,

however, we did find that the gender difference in ABPamong parents was greatest at low levels of maritalsatisfaction and virtually disappeared at high levels ofmarital satisfaction. However, among women, high levelsof marital satisfaction did not buffer the effect of childless-ness, suggesting childlessness may have a stronger influ-ence on cardiovascular functioning among women and/orthe mechanisms differ among men and women.

While our overall findings may seem surprising (partic-ularly for any mother who may be reading this and askingherself in disbelief “how is it possible these kids arelowering my blood pressure?!”), our results are consistentwith and build upon prior research. The experience ofpregnancy, lactation, and offspring exposure appear tointeract in the alterations of female brain and behavior.Animal research provides evidence that motherhood, singleor multiple reproductive experiences, attenuates neuro-behavioral stress and fear responses [50]. Oxytocin, ahormone closely linked to pregnancy and lactation, hasbeen identified as a mediator of the blunted stress responsein both animals and humans [51]. For example, research inhumans demonstrates reduced blood pressure reactivity inresponse to stress among breast-feeding mothers [52].While many assume that this effect would dissipate after amother stops nursing (i.e., weaning), evidence suggests thatneurological changes extend beyond periods of lactationand may be permanent [41, 50, 53]. Researchers havefound that the neurons that produce oxytocin in the brain ofa rat are actually restructured by giving birth and nursing[54]. This antistress system has been argued to beevolutionarily adaptive, as reduced stress responsivenessand fear may help a mother protect her offspring [55].

These data are also consistent with a large body ofepidemiological, clinical, and experimental research sug-gesting a reduced health risk associated with pregnancy—childlessness and delayed childbearing are associated withgreater risk for breast cancer [56]. This protective effect iswell-established in both humans and in mammalian animalmodels. Although breast cancer susceptibility is influencedby many exogenous and endogenous factors, pregnancy-protection explanations include both endocrine and immu-nologic factors associated with pregnancy [57, 58] that maypotentially extend to cardiovascular outcomes.

A number of socio-cultural factors may also be influential.Caring for children can be a meaningful activity for parents asit provides a sense of purpose and role fulfillment for couples,particularly married couples whose normative role expect-ations include parenthood. A recent national survey onmarriage and parenting found that, despite recent decreases,respondents rated children as “very important” for a success-ful marriage [27]. Children were also rated as a primarysource of personal fulfillment. Further, “children occupy apedestal matched only by spouses and situated well above

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that of jobs, career, friends, hobbies, and other relatives”[27]. Likewise, approximately 94% of men and womeneither agreed or strongly agreed with the statement, “therewards of being a parent are worth it, despite the cost andwork it takes”[59]. Therefore, while caring for children mayinclude daily hassles, deriving a sense of meaning andpurpose from life stressors has been shown to be associatedwith better health outcomes [21], and the same may be truefor couples with children. Conversely, research suggests thatothers perceive childlessness and size of family as voluntaryand attribute more negative characteristics to childlesswomen [60]. Thus, there may be real negative socialconsequences associated with violating the norm of a“motherhood mandate.” Likewise, there may be considerablestress among couples who are not parents but desire to be so.

While we found that the influence of parental status wasconsistent across stages of parenting, it is possible that themechanisms responsible may vary according to stage. Forinstance, mothers of infants and toddlers may be benefitingfrom the heightened oxytocin that is associated withbreastfeeding and frequent close physical contact; mothersof school-age children may benefit from greater diversity ofrelationships/network ties (e.g., involvement with school,extracurricular activities, and other parents); and mothers ofadult children may benefit from reciprocated social supportfrom their children. Research from a nationally representa-tive sample points to a positive relationship betweenparenting and ties to social (marriage, neighbor, confidant,kin) networks, such that parents have significantly greatersocial integration than those who are “permanently”childless, and level of involvement in social networksamong parents is greater at later stages of parenting thanearlier stages [61]. However, more research (particularlyusing longitudinal methods) is needed to establish theactual mechanisms for the effects we found. Future researchon neuro-behavioral stress responsiveness among humans,which also accounts for socio-cultural forces, is needed.

It is important to acknowledge potential limitations tothis study. First, we sampled over only one day. It ispossible that longer assessment periods followed over timemay more accurately reflect BP. Second, our sample waspredominantly white and educated. Ituarte found racialdifference in nocturnal BP dipping and that among Blacksparents were less likely to dip at night– suggesting apotential moderating effect of race on the influence ofparental status [17]. Ituarte and colleagues further argue thatthe influence of race on BP dipping among parents mayhave been a proxy for some other variable such as increasedstress due to finances. Thus, it is possible that parentalstatus may not afford the same benefits among samples thatmay lack adequate resources. It is possible that parents whofind themselves in more difficult social or economic homeenvironments or are caring for children with special needs

may be linked to detrimental influences [4]. Rich informa-tion on the home environment was unavailable in thecurrent study and future work should focus on moredetailed assessments of the family context in whichparenting occurs. In addition, we examined only marriedheterosexual couples. It is unclear to what extent homosex-ual, cohabitating, and/or dating couples may differ frommarried couples or the extent to which other types ofparents (adoptive, step-parent, or single) may differ. Thus,future research would be needed to determine the extent towhich these findings generalize more broadly.

Despite any limitations, this study has a number ofstrengths. To date only two other studies report the effect ofparenthood on ABP [17, 20]; however, parental status wasnot a primary focus of either study and each examinedparental status within relatively small samples and atrestricted time points (evening hours or during sleep). Ourresearch found gender differences that have not been seenin previous research that are consistent with animal modelsof attachment caregiving.

Overall we believe that these findings have importantimplications. They suggest that despite the potential dailystrain associated with parenting, having children does notseem to be associated with detrimental physiological process-es but rather may be cardio-protective, particularly amongwomen. This study may serve as a starting point by which wemay begin to systematically examine the complex factors thatmay influence the effect of parental status.

Acknowledgements This research was generously supported bygrant number R0502042 from the Marchionne Foundation and a grantfrom the Family Studies Center at Brigham Young University awardedto Dr. Julianne Holt-Lunstad. We would like to thank Brandon Jones,Shayna Ernhofer, Laura Cummings, Chad Jenson, Brian Mead, andBritta Thunnell for their help running participants through theprotocol.

This data was previously presented at the 2008 Society ofBehavioral Medicine annual meeting in San Diego, where it receivedthe Citation Award for Excellence in Research.

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