This population-based study of stress and HRQoL in mothers of children born VLBW contributes new and salient findings to the literature. Our results indicate differential effects of parenting a VLBW child on future maternal HRQoL, supporting prior work [6
]. Specifically, our study found that when the children are age five, maternal physical health is worse among VLBW mothers while mental HRQoL did not differ between mothers of VLBW and NBW children. This study also revealed that stress appears to mediate the relationship between having a VLBW child and maternal physical HRQoL. This study also examined early maternal and child predictors of maternal HRQoL among mothers of VLBW children. Specifically, our results suggest that while the severity of VLBW children’s health problems at birth was associated with maternal physical
HRQoL when children were age five, maternal mental
HRQoL is more strongly associated with child well-being and behavior problems.
Most existing studies of stress in parents of preterm or VLBW children have focused specifically on parenting
], yielding conflicting results. Our study shows that parents of VLBW children have worse general
stress (including psychological and somatic) than parents of NBW children. Moreover, stress appears to attenuate the relationship between caring for a child born VLBW and physical HRQoL, suggesting one potential pathway by which poor physical HRQoL may occur. Parenting stress and other stressors associated with caring for a VLBW child may contribute to chronic stress, which may in turn lead to poor physical HRQoL as we have reported previously [25
Previous research has established the relationship between child behavior problems and deleterious outcomes among parents of VLBW children [2
]; and this study confirms that child behavior problems at age two are significantly associated with worse maternal mental HRQoL when the child was age five. It is possible that our measurement of child behavior characteristics at age two was indicative of continued behavior problems at age five [26
]. The stress of caring for a child with behavior problems may also accumulate and lead to worse maternal mental HRQoL over time. Future longitudinal research using sophisticated statistical models should be conducted to better understand these nuanced relationships.
Pre-pregnancy health problems (specifically, diabetes and hypertension) were also found to be associated with maternal mental HRQoL when the child was age five. Given the chronic nature of these health problems, it is likely that women who experienced these problems prior to pregnancy continued to experience them when the child was age five. Our findings also indicate that stress may mediate this relationship. Managing long-term chronic health conditions such as hypertension or diabetes may cause additional stress for mothers of children born VLBW that negatively influences their mental well-being, over and above caregiving alone.
Interestingly, maternal physical HRQoL was associated with a very different set of maternal and child factors. The association with health problems during pregnancy is unsurprising, given that such factors can be a barometer for future health problems [28
]. However, the length of time the child spent in the NICU was independently
associated with poor maternal physical HRQoL when the child was five, even after controlling for health problems during pregnancy, an important predictor of subsequent physical health of both the mother and child. Although it is possible that this may be due to incomplete ascertainment of prior health problems, direct and indirect effects of the length of the NICU stay on maternal HRQoL are certainly plausible. In addition, the child’s health problems that lead to a prolonged NICU stay [30
] may cause uncertainty and distress that may negatively impact mothers. The NICU environment itself can be incredibly stressful for parents [31
], and being a new mother is already a particularly emotional and overwhelming time. Thus, a prolonged separation from the newborn while in the NICU may expose new mothers to a tremendous life stressor when they are particularly vulnerable [33
]. Such a monumental life event could causes an intense short term psychological response and corresponding long term physiological responses for mothers, explaining why length of stay in the NICU was associated with maternal physical
health five years later, but not maternal mental
health five years out.
Importantly, the relationship between the length of the NICU stay and maternal physical HRQoL was not influenced by child health problems at age two. This strengthens our interpretation of the results by indicating that enduring child health problems alone do not account for the effect of the NICU stay on poor subsequent maternal physical health. Previous work on the effects of stress indicates that chronic stress, even once resolved, can have long-term physiological influences on the body [36
]. The intense conditions of the NICU environment, or the child’s health problems for which length of NICU stay is a proxy, may incite a lasting physiologic response in mothers that is not influenced by children’s health problems at later stages in the child’s life.
The differences we see in the factors associated with physical and mental HRQoL suggest an interesting life-course trajectory connecting the birth of a VLBW child with parental outcomes. It is possible that the experience of having a VLBW child sets parents on a trajectory in which physical health is compromised over time, even when mental health returns to normal. The immediate stressor of having a child in the NICU may contribute to long-term physical health problems in mothers, without negatively impacting mental health long-term. Other ongoing aspects associated with caring for a VLBW child however, such as behavior problems, may be responsible for a lack of re-adjustment in mental health in some mothers over time, without immediately influencing physical health.
The evidence from this and other studies indicates that maternal HRQoL is influenced over time by factors of both the mother and the child. Therefore, parent, child, and family level interventions throughout the life-course may be advantageous in protecting families from the deleterious effects of caregiving. Future research should more closely examine the impact of stress immediately following the birth of a VLBW child on the long-term physical health of the family. Further, research exploring the impact of child-level behavioral interventions on maternal mental health is needed.
Study Limitations and Strengths
Several limitations of this study should be considered. First, a larger proportion of NBW parents than VLBW parents participated in this ancillary follow-up survey. However, it is likely that those who did not participate in our follow-up survey were experiencing the greatest stress and worst HRQoL. Excluding mothers with the worst outcomes would have biased our case-comparison outcomes toward an underestimation of the true effect of caring for a VLBW child.
Second, child behavior problems and HRQoL are based on parent reports, which may be influenced by parents’ own health and mental health status. However, studies have indicated that maternal depressive symptoms do not substantially bias maternal reporting of externalizing behaviors [37
] or internalizing behavior.[38
Finally, limitations in the dataset restricted our ability to fully explore maternal health problems in our analysis of physical HRQoL. Our analysis of maternal pre-pregnancy health was limited to diabetes and hypertension; therefore, our results may be impacted by residual confounding of maternal health problems prior to and during pregnancy. However, a sensitivity analysis revealed that adjusting for maternal health problems did not substantially impact the effect of NICU stay on maternal physical health, indicating that this association may be independent of prior health. In addition, we were unable to examine child health and well-being factors at age five. Future research should examine whether these factors play a role in concurrent maternal physical or mental well-being.
This study also has important strengths. Our study approaches the association between caring for a VLBW child and maternal health from a life-course perspective. By looking at the effects of child health and well-being over time, we were able to identify the long-term effects of child-level factors at specific points in the caregiving directory. In addition, our study is population-based, whereas most previous studies are gathered from clinics, limiting their generalizability. Finally, this study uses a measure of parental biopsychosocial symptoms
of stress [19
], which may better capture the physiologic impact of parenting a VLBW child.